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THE  SCHUYLKILL   COUNTY 
MEDICAL   LIBRARY 

$    NO.. 

•  • 


PRESENTED   BY 


A 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


AN 


ELEMENTARY   TREATISE 


HUMAN  ANATOMY. 


BY 

JOSEPH    LEIDY,    M.D., 

PROFESSOR    OF    ANATOMY  IN   THE    UNIVERSITY   OF   PENNSYLVANIA;    CURATOR    OF   THE    ACADEMY   OF   NATURAL 

SCIENCES;    MEMBER    OF   THE  AMER.   PHILOS.  SOC.  J    COL.   OF    PHYSICIANS,    PHILADELPHIA;    AMER.  ACAD. 

OF    ARTS    AND    SCIENCES;     NAT.    HIST.    SOC.,    BOSTON;     LYC.    NAT.    HIST.,    NEW   YORK;     ELLIOT 

NAT.  HIST.  SOC.,  CHARLESTON;    MED.  SOC.  OF  VIRGINIA;    ACAD.  OF  SCIENCES,  ST.  LOUIS; 

IMP.     SOC.    OF    NATURALISTS,     MOSCOW;     IMP.     LEOPOLD.    CAROL.    ACAD.     OF 

SCIENCES,  JENA  ;    BOY.  ACAD.  OF  SCIENCES,  MUNICH  ;   BIOLOG.  SOC., 

PARIS;    soc.   OF  ARTS   AND   SCIENCES,   MONS;    ZOOLOG. 
soc.,  LQNDON;    UNIV.  ZOOL.  AND  EOT.   ASSOO., 

DUBLIN,  ETC. 


WITH  THREE  HUNDRED-  AND  NINETF-TWO  ILLUSTRATIONS. 


PHILADELPHIA  : 

J.    B.    LIPPINCOTT    &    CO. 
1861. 


Entered,  according  to  act  of  Congress,  in  the  year  1860,  by 

JOSEPH    LEIDY,    M.D., 

In  the  Clerk's  Office  of  the  District  Court  of  the  United  States  for  the  Eastern 
District  of  Pennsylvania. 


PREFACE. 


As  indicated  by  its  title,  the  present  work  is  intended  as  an 
elementary  treatise  on  human  anatomy,  and  is  not  an  elaborate 
system  adapted  to  the  use  of  those  who  have  already  advanced  in 
anatomical  knowledge.  The  author  has  attempted  to  prepare  such 
a  book  as  he  feels  would  have  been  of  service  to  himself  in  the 
commencement  of  his  studies,  and  he  hopes  it  may  be  found 
worthy  of  the  approbation  of  students,  for  whom,  and  by  whose 
frequent  solicitation,  it  was  written. 

Much  of  the  difficulty,  of  which  we  hear  constant  complaint, 
in  the  acquisition  and  retention  of  anatomical  knowledge,  arises 
from  an  excessive,  and,  in  some  other  respects,  objectionable  no- 
menclature. Not  only  has'  the  naming  of  comparatively  unim- 
portant parts  been  carried  to  an  extreme,  but,  in  numerous 
instances,  the  same  parts  are  designated  by  a  multitude  of  names, 
which  are  indiscriminately  used  by  different  writers.  The  nomen- 
clature of  anatomy  has  been  founded  on  no  particular  system ; 
the  names  having  been  chosen,  according  to  the  fancy  of  anato- 
mists, from  the  shape,  function,  or  supposed  resemblance  of  the 
part,  or  in  commemoration  of  the  original  investigator.  In  some 
measure  to  avoid  the  difficulty  to  which  we  refer,  the  author  has 
adopted  the  plan  of  generally  using  a  single  name  for  each  part ; 

(iii) 


iv  PREt 

of  the  many  names  employed,  to  use  that  which  is  most  expres- 
sive of  the  character  of  the  part ;  and,  when  admissible,  the 
name  is  anglicized.  A  copious  synonymy  is  added,  in  foot-notes, 
which  may  be  found  useful  for  future  reference. 

Many  of  the  drawings  accompanying  the  work  are  original, 
and  were  made  by  the  author,  or  by  his  friend  Dr.  H.  D.  Schmidt, 
favorably  known  for  his  anatomical  investigations.  The  excellent 
wood  engravings,  with  few  exceptions,  are  from  the  masterly  hand 
of  August  Wilhelm,  a  young  artist  of  this  city. 


CONTENTS. 


CHAPTER  I. 

PAGE 

INTRODUCTION          -        -        -        -        -        -        -        -        -        -        -        -17 

Ultimate  Chemical  Elements  of  the  Human  Body       ....         25 

Proximate  Chemical  Elements  of  the  Human  Body        -         -         -         -     20 

Group  1.  Nitrogenized  Elements  peculiarly  Organic  26 

"      2.  Non-Nitrogenized  Elements  peculiarly  Organic          -         -     27 
"      3.  Elements  not  peculiarly  Organic  -----         28 

"  .   4.  Elements  arising  from  the  disintegration  of  the  different 
parts  of  the  body,  for  the  most  part  expelled  in  the 
excretion  ---------28 

Ultimate  Physical  Elements  of  the  Human  Body  29 

The  Proximate  Physical  Elements  of  the  Tissues  of  the  Human  Body    -     32 

CHAPTER  II. 
THE  SKELETON        --___-____-_    33 

Development  and  Growth  of  the  Skeleton 42 

Articulations  or  Joints  of  the  Skeleton  -         -        -         -         -         -     46 

Of  the  Relative  Position  of  the  Different  Structures  entering  into  the 

Composition  of  Articulations  -------     48 

Bones  of  the  Head  or  Skull 50 

Bones  of  the  Cranium  ----------50 

The  Occipital  Bone 50 

The  Sphenoid  Bone 52 

The  Ethmoid  Bone     -  56 

The  Frontal  Bone "-         -         -         -58 

The  Parietal  Bone ---60 

The  Temporal  Bone 61 

Structure  and  Articulation  of  the  Bones  of  the  Cranium  65 

General  Conformation  of  the  Cranium  -------67 

Mechanical  Construction  of  the  Cranium  ------         70 

Development  of  the  Cranium         --------73 

Supernumerary  Bones  of  the  Cranium 75 

Bones  of  the  Face         ----------     75 

The  Superior  Maxillary  Bone     --------         7G 

The  Palate  Bone 78 

The  Lachrymal  Bone          -----__-_         80 

The  Nasal  Bone 81 

The  Turbinated  Bone         -         - 81 

The  Vomer 82 

The  Malar  Bone 83 


vj  CONTENTS. 

THE  SKELETON — Continued.  PAGE 

The  Inferior  Maxillary  Bone       -  83 

Structure  and  Articulation  of  the  Bones  of  the  Face         ...  85 

The  Temporo-maxillary  Articulation   -  86 

General  Conformation  and  Position  of  the  Face         -  87 

The  Side  of  the  Skull 88 

The  Base  of  the  Skull  90 

The  Orbits -  91 

The  Nasal  Cavities 92 

Development  of  the  Face -94 

Changes  of  the  Skull  at  Different  Periods  of  Life  94 

The  Hyoid  Bone 96 

The  Trunk 96 

The  Vertebral  Column 97 

The  True  Vertebra  97 

The  Cervical  Vertebrae ----99 

The  Dorsal  Vertebrse 102 

The  Lumbar  Vertebrae                                                       ...         -  103 

The  False  Vertebrae                                               103 

The  Sacrum 104 

The  Coccyx 105 

Development  of  the  Vertebrae      --'.;-  ----106 

Articulations  of  the  Vertebral  Column 107 

Articulations  of  the  Occipital  Bone,  the  Atlas,  and  the  Axis         -         -  111 

The  Vertebral  Column  viewed  Entire        -        -         -.                -         -  113 

The  Ribs 114 

The  Sternum    -                                               - 117 

Articulations  of  the  Ribs  with  the  Vertebrae  and  Sternum  -        -         ^118 

The  Thorax     -  119 

The  Hip  or  Innominate  Bones      -                                                                -  121 

Articulations  of  the  Hip  Bones        -------  125 

The  Pelvis                                                                                                       -  126 

Sexual  Differences  of  the  Pelvis -128 

The  Upper  Extremities        -_.-                  .___  129 

Bones  of  the  Shoulder     ------                  ...  129 

The  Clavicle 129 

The  Scapula    -                                                                                           -  130 
Bones  of  the  Arm  and  Forearm  -        -        -         -         -        -         -         -132 

The  Humerus  -                                                                                  -         -  132 

The  Ulna 134 

The  Radius                                                                                              ,   ,-  '  135 

Bones  of  the  Hand      -                                                                                  -  136 

Bones  of  the  Carpus  136 

Bones  of  the  Metacarpus     ---------  138 

Bones  of  the  Fingers 139 

The  Hand  -                                                                                                 -  140 

Development  of  the  Bones  of  the  Upper  Extremities         -  141 
Articulations  and  Movements  of  the  Upper  Extremities. — The  Sterno- 

clavicular  Articulation 141 


CONTENTS.  Vii 

THE  SKELETON — Continued.  PAGE 

The  Scapulo-clavicular  Articulation  -------  142 

The  Shoulder  Joint  -  - 143 

The  Elbow  Joint  -  -  -  - 144 

The  Superior  Radio-ulnar  Articulation  -  -  -  -  -  -  145 

The  Middle  "  " 145 

The  Inferior  "  " 145 

The  Wrist  Joint,  or  Radio-carpal  Articulation  -----  146 

The  Intercarpal  and  Carpo-metacarpal  Articulations  -  147 

The  Metacarpo-phalangial  and  Phalangial  Articulations  -  147 

The  Lower  Extremity 148 

The  Femur 148 

The  Patella 150 

The  Bones  of  the  Leg 150 

The  Tibia 150 

The  Fibula  - 152 

Bones  of  the  Foot -----  153 

Bones  of  the  Tarsus 153 

Bones  of  the  Metatarsus 156 

Bones  of  the  Toes 157 

The  Foot  157 

Development  of  the  Bones  of  the  Lower  Extremity  -  158 

Articulations  and  Movements  of  the  Lower  Extremities  -  -  -  158 

The  Hip  Joint 159 

The  Knee  Joint 160 

The  Tibio-fibular  Articulations 163 

The  Ankle  Joint 163 

The  Intertarsal  and  Tarso-metatarsal  Articulations — Articulations  of 

the  Astragalus,  Calcaneum,  and  Scaphoid  Bone  -  -  -  -  164 

Articulation  of  the  Calcaneum  and  Cuboid  Bone  -  -  -  -  165 
Articulation  of  the  Scaphoid,  Cuboid,  and  Cuneiform  Bones  together  and 

with  the  Bases  of  the  Metatarsal  Bones  -----  165 

Metatarso-phalangial  and  Phalangial  Articulations  -  -  -  -  166 

CHAPTER  III. 

THE  FIBROUS,  CARTILAGINOUS,  FIBRO-CARTILAGINOUS,  ELASTIC,  AND  ADIPOSE 

TISSUES 167 

Fibrous  Tissue         ....  167 

Cartilage  and  Fibro-cartilage       -         -         - 171 

Elastic  Tissue 175 

Adipose  Tissue --176 

CHAPTER  IV. 

THE  MUSCULAR  SYSTEM        -        -        -        -        -        -        --        -        -  178 

General  Remarks  on  the  Head 183 

Fascia  of  the  Head      ---- 185 

Muscles  of  the  Scalp 185 

Muscles  of  the  Eyelids  and  Eyebrows           ------  187 


viii  CONTENTS. 

THE  MUSCULAR  SYSTEM — Continued.  PAGE 

Muscles  of  the  Nose 188 

Muscles  of  the  Lip  and  Cheek     -         -        -         -         r         -         -        -  188 

The  Muscles  of  the  Lower  Jaw,  or  of  Mastication    -  191 

The  Neck    -                                    -  193 

Muscles  and  Fasciae  of  the  Neck. — The  Subcutaneous  Cervical  Muscle  193 

The  Cervical  Fascia     -• 194 

The  Sterno-mastoid  Muscle 195 

Depressors  of  the  Hyoid  Bone  and  Larynx            -  195 

Elevators  of  the  Hyoid  Bone  and  Larynx          -        -         -         -         -  196 

Deep  Muscles  of  the  Front  of  the  Neck        -         -         -        -         -         -197 

Topographical  Sketch  of  the  Anatomy  of  the  Neck  -  199 

Front  of  the  Thorax 200 

Muscles  of  the  Front  and  Sides  of  the  Thorax  201 

The  Back -         -         -         -  203 

Superficial  Muscles  of  the  Back        -----                  -  203 

Deep  Muscles  of  the  Back,  or  Extensors  of  the  Head  and  Trunk           -  206 

Muscles  of  the  Ribs 210 

The  Abdomen      ------ 211 

Superficial  Fascia  of  the  Abdomen 212 

Muscles  of  the  Abdomen     -        -         -        -         -         -        -        -        -213 

The  Lumbar  Fascia 218 

The  Transverse  Fascia  of  the  Abdomen 218 

The  Inguinal  Canal 219 

Remarks  on  Inguinal  Hernia        -         -         -         -         -         -         -        .  -  220 

The  Diaphragm -  221 

The  Upper  Extremity 223 

Fasciae  of  the  Upper  Extremity 224 

Muscles  of  the  Shoulder 226 

Muscles  of  the  Arm 227 

Muscles  of  the  Front  of  the  Forearm 230 

Muscles  of  the  Back  of  the  Forearm        -  233 

Muscles  of  the  Hand 236 

Muscles  of  the  Ball  of  the  Thumb   - 236 

Muscles  of  the  Little  Finger        -         - 237 

The  Interosseous  Muscles          - 237 

The  Lower  Extremities -         -         -  238 

Fasciae  of  the  Lower  Extremity 238 

Sketch  of  the  Anatomy  concerned  in  Femoral  Hernia            -         -         -  242 

Muscles  of  the  Buttock 244 

The  Iliac  Fascia 247 

Muscles  of  the  Iliac  Region  and  Loin       -         -        -        -        -        -  247 

Muscles  on  the  Front  of  the  Thigh -  248 

Muscles  on  the  Back  of  the  Thigh 250 

Muscles  of  the  Front  and  Outer  Part  of  the  Leg,  and  Upper  Part  of  the 

Foot  252 

Muscles  on  the  Back  of  the  Leg 254 

Muscles  of  the  Sole  of  the  Foot 256 

The  Interosseous  Muscles  of  the  Foot 258 


CONTENTS.  ix 


CHAPTER  V. 

PAGE 

ANATOMICAL  ELEMENTS  OF  SEROUS  AND  Mucous   MEMBRANES,  THE  GLANDS, 

THE  LUNGS,  AND  THE  SKIN   ---------  259 

Serous  Membranes  ----------  268 

Mucous  Membranes     ----------  266 

The  Glandular  System 267 

Unstriated  Muscular  Tissue         --------  271 


CHAPTER  VI. 

THE  ALIMENTARY  APPARATUS        _________  273 

The  Mouth 273 

Muscles  of  the  Palate  and  Fauces         -------  277 

The  Salivary  Glands 278 

The  Tongue 280 

Muscles  of  the  Tongue 283 

The  Teeth 285 

Characters  of  the  Permanent  Teeth 286 

Characters  of  the  Temporary  Teeth 288 

Structure  of  the  Teeth 289 

Development  of  the  Teeth 292 

The  Pharynx 294 

Muscles  of  the  Pharynx       ---------  295 

The  (Esophagus        --------__  297 

The  Cavity  of  the  Abdomen         -         -         -         -  -         -        -  298 

The  Peritoneum       -------.._  300 

The  Stomach 395 

The  Small  Intestine 309 

The  Large  Intestine -  315 

The  Rectum 318 

The  Pancreas        --__._„_  ._  320 

The  Liver 321 

Structure  of  the  Liver         ----...__  324 

Biliary  Ducts  and  Gall-bladder 328 

The  Spleen          - 329 

CHAPTER  VII. 

THE  VASCULAR  SYSTEM 332 

General  Character  of  the  Arteries     -------  332 

General  Character  of  the  Veins 335 

The  Capillaries ....  337 

The  Blood 333 

The  Heart 341 

Structure  of  the  Heart         -         -        -         -• 347 

The  Pericardium 349 

Mechanism  of  Action  of  the  Heart 349 

The  Arteries 351 


x  CONTENTS. 

THE  VASCULAR  SYSTEM — Continued.  PAGE 

The  Aorta 351 

The  Arch  of  the  Aorta     -         -  351 

The  Coronary  Arteries         ._-------  353 

The  Innominate  Artery    ---------  353 

The  Common  Carotid  Artery ---  354 

The  External  Carotid  Artery 355 

The  Internal  Carotid  Artery 363 

The  Subclavian  Arteries 367 

The  Axillary  Artery -  372 

The  Brachial  Artery 374 

The  Radial  Artery        -                                            376 

The  Ulnar  Artery 379 

Thoracic  Aorta 381 

Abdominal  Aorta     ----------  383 

The  Coeliac  Axis -        -         -         -  384 

The  Superior  Mesentery  Artery 386 

The  Inferior  Mesentery  Artery 388 

The  Middle  Sacral  Artery         - 389 

Arteries  in  Pairs  from  the  Abdominal  Aorta         -  389 

The  Common  Iliac  Arteries       --------  390 

The  Internal  Iliac  Artery 391 

The  External  Iliac  Artery 395 

The  Femoral  Artery 396 

The  Popliteal  Artery 399 

The  Anterior  Tibial  Artery 400 

The  Dorsal  Pedal  Artery  401 

The  Posterior  Tibial  Artery                                                                           *  402 

The  Pulmonary  Artery 405 

The  Veins 405 

The  Coronary  Vein 405 

The  Superior  Cava      ...        -                                                      -  406 

The  Innominate  Veins      - 406 

Veins  of  the  Head  and  Neck -  408 

The  Internal  Jugular  Vein 409 

Sinuses  of  the  Dura  Mater  -        -         -"-        -        -        -        -        -  409 

Veins  of  the  Brain  - 412 

The  Diploic  and  Meningeal  Veins         -------  413 

The  Ophthalmic  Vein 413 

The  External  Jugular  Vein  -        -        -        -        -        -        -         -413 

The  Facial  Vein 414 

The  Temporal  Vein -  414 

The  Internal  Maxillary  Vein 415 

The  Temporo-maxillary  Vein       --------  415 

The  Posterior  Auricular  Vein 415 

The  Occipital  Vein                                                                                         -  416 

The  Veins  of  the  Tongue  416 

The  Pharyngeal  Vein 416 

The  Superior  Thyroid  Veins 416 


CONTENTS. 


XI 


THE  VASCULAR  SYSTEM — Continued. 

The  Veins  of  the  Upper  Extremities    ------ 

The  Subclavian  Vein        -------- 

The  Deep  Veins  of  the  Upper  Extremity      -         -        -         -         - 

The  Superficial  Veins  of  the  Upper  Extremity 
The  Azygos  Vein         -         -         -         -        -- 

The  Inferior  Cava    - 

Branches  of  the  Inferior  Cava     ------- 

The  Portal  Vein 

The  Veins  of  the  Vertebral  Column     ------ 

The  Common  Iliac  Veins  ------- 

The  Internal  Iliac  Vein        -___-___ 
The  External  Iliac  Vein 

The  Deep  Veins  of  the  Lower  Extremity 

The  Superficial  Veins  of  the  Lower  Extremity  - 

The  Pulmonary  Veins 

The  Lymphatic  System     -------- 

The  Trunks  of  the  Lymphatic  System 

The  Thoracic  Duct 

The  Right  Lymphatic  Duct  -_--._. 

Lymphatics  of  the  Head  and  Neck  ------ 

Lymphatics  of  the  Cranial  Cavity 

Lymphatics  of  the  Exterior  of  the  Cranium      -         -        -         - 

Lymphatics  of  the  Face 

Lymphatics  of  the  Neck  -------- 

Lymphatics  of  the   Upper  Extremities,   and  of   the  Exterior  of 

Thorax 

Lymphatics  of  the  Cavity  of  the  Thorax      - 
Lymphatics  of  the  Lower  Extremities  and  of  the  Pelvis    - 
Lymphatics  of  the  Cavity  of  the  Abdomen  -        -        -         -         - 


the 


PAGE 

416 
417 
417 
417 
419 
420 
420 
421 
423 
423 
424 
425 
426 
426 
428 
428 
430 
431 
432 
432 
432 


433 
434 
434 

435 
435 
437 

438 


CHAPTER  VIII. 

THE  VOCAL  AND  RESPIRATORY  APPARATUS    - 
The  Larynx       - 

Cartilages  of  the  Larynx     -        -         -         - 
Articulations  and  Ligaments  of  the  Larynx 
Muscles  of  the  Larynx         - 
The  Cavity  of  the  Larynx 
The  Organs  of  Respiration 

The  Trachea 

The  Lungs  ------- 

The  Pleura 

The  Thyroid  Body 

The  Thymus  Body    -  ... 


440 
440 
440 
442 
443 
445 
447 
447 
450 
454 
455 
456 


xii  CONTENTS. 


CHAPTER  IX. 

PAGE 

THE  URINARY  ORGANS 458 

The  Kidneys 458 

The  Urinary  Bladder -  462 

The  Urethra 465 

The  Supra-renal  Bodies       ---------  465 

CHAPTER  X. 

THE  GENERATIVE  APPARATUS        -        --        -        -        -        -        -        -  468 

The  Male  Organs  of  Generation        -------  468 

The  Testicles 468 

The  Seminal  Vesicles  and  Ejaculatory  Ducts 473 

The  Penis 475 

The  Urethra  of  the  Male 478 

The  Prostate  and  Suburethral  Glands 480 

The  Female  Organs  of  Generation    -------  481 

The  Uterus 481 

Ligaments  of  the  Uterus 484 

The  Ovaries 485 

The  Parovarium       -----         -..._  437 

The  Fallopian  Tubes,  or  Oviducts 488 

The  Vagina 489 

The  Vulva -         ...  491 

The  Cavity  of  the  Pelvis  494 

The  Perineum 496 

The  Pelvic  and  Perineal  Fascise 496 

Muscles  of  the  Perineum.     ---------  498 

The  Mammae 499 

CHAPTER  XI. 

THE  NERVOUS  SYSTEM 503 

General  Character  and  Structure  of  the  Cerebro-spinal  Axis    -         -  503 

General  Character  and  Structure  of  the  Cerebro-spinal  Nerves              -  507 

Origin  and  Termination  of  the  Cerebro-spinal  Nerves        -•'•'•  509 

General  Character  and  Structure  of  the  Sympathetic  Nerves        -        -  511 

General  Character  and  Structure  of  the  Ganglia       -  512 

The  Cerebro-spinal  Axis,  or  Brain  and  Spinal  Cord      -        -        -        -  513 

The  Brain 514 

The  Cerebrum 515 

Fornix                                - 521 

Pellucid  Septum 521 

Lateral  Ventricles 621 

Corpora  Striata,  or  Striated  Bodies      -        -        -                 -        -        -  523 

Third  Ventricle 523 

Thalami 524 

Quadrigeminal  Body 525 


CONTENTS.  xiii 

THE  NERVOUS  SYSTEM — Continued.  PAGE 

Pineal  Gland 526 

Commissures  of  the  Third  Ventricle 526 

The  Cerebellum 526 

Dentated  Body --  528 

Crura  of  the  Cerebellum 528 

The  Pons 529 

The  Medulla  Oblongata 530 

Fourth  Ventricle 531 

The  Spinal  Cord 533 

Membranes  of  the  Brain  and  Spinal  Cord         -----  535 

The  Pia  Mater 535 

Pia  Mater  of  the  Brain 535 

Pia  Mater  of  the  Spinal  Cord 536 

The  Ependyma         ---- 537 

The  Dura  Mater 537 

Dura  Mater  of  the  Brain           -        -         -         --         -         -        -  537 

Dura  Mater  of  the  Spinal  Cord 539 

The  Arachnoid  Membrane         --------  539 

The  Nerves  of  the  Brain,  or  the  Cerebral  Nerves           -         -         -         -  540 

The  Olfactory,  or  First  Pair  of  Nerves -  540 

The  Optic,  or  Second  Pair  of  Nerves 541 

The  Oculo-motor,  or  Third  Pair  of  Nerves        -----  541 

The  Pathetic,  or  Fourth  Pair  of  Nerves 542 

The  Trifacial,  or  Fifth  Pair  of  Nerves      -  542 

The  Ophthalmic  Nerve                                                                                    -  543 

The  Ophthalmic  Ganglion          --------  544 

The  Superior  Maxillary  Nerve     --------  545 

The  Spheno-palatine  Ganglion          --_____  545 

The  Inferior  Maxillary  Nerve      --------  543 

The  Otic  Ganglion ._         ...  559 

The  Submaxillary  Ganglion          --------  559 

The  Abducent,  or  Sixth  Pair  of  Nerves 550 

The  Facial,  or  Seventh  Pair  of  Nerves          ------  551 

The  Auditory,  or  Eighth  Pair  of  Nerves  ----*--  553 

The  Glosso-Pharyngeal,  or  Ninth  Pair  of  Nerves           -  553 

The  Pneumogastric,  or  Tenth  Pair  of  Nerves    -----  555 

The  Accessory,  or  Eleventh  Pair  of  Nerves           -----  553 

The  Hypoglossal,  or  Twelfth  Pair  of  Nerves     -                  ...  559 

The  Spinal  Nerves 559 

The  Cervical  Nerves -         -  561 

Posterior  Branches  of  the  Cervical  Nerves  ------  561 

Anterior  Branches  of  the  Cervical  Nerves         -         -         -         -         -  562 

The  Cervical  Plexus     ----- 562 

The  Brachial  Plexus 563 

The  Thoracic  Nerves 570 

Posterior  Branches  of  the  Thoracic  Nerves       -----  571 

Anterior  Branches  of  the  Thoracic  Nerves 571 

The  Intercostal  Nerves 571 


xiy  CONTENTS. 

THE  NERVOUS  SYSTEM — Continued.  PAGE 

The  Lumbar  Nerves    ----------  572 

The  Lumbar  Plexus          ---- 573 

The  Sacral  and  Coccygeal  Nerves         -------  57$ 

The  Sacral  Plexus -_-.  577 

The  Sympathetic  System  of  Nerves      -         -         -        -                  -        -  581 

Cervical  Portion  of  the  Sympathetic  Nerve 582 

The  Cardiac  Plexus 584 

'  Thoracic  Portion  of  the  Sympathetic  Nerve 585 

The  Solar  Plexus 585 

Lumbar  and  Sacral  Portions  of  the  Sympathetic  Nerves   -        -         -  587 

The  Hypogastric  Plexus 587 


CHAPTER  XII. 

THE  ORGANS  OF  SPECIAL  SENSE    ---------  588 

The  Nose  588 

The  Nasal  Cavities       -                                                                                  -  591 

The  Eye  594 

The  Eyebrows     -----------  595 

The  Eyelids     -         -        -  595 

The  Conjunctiva          __--__-_-.  597 

The  Lachrymal  Apparatus        --------  593 

The  Eyeball         -                                                                                           -  600 

Muscles  of  the  Eyeball    -         -         -         -  601 

The  Sclerotica     -         -         -         - 602 

The  Cornea 603 

The  Choroidea -  604 

The  Iris 607 

The  Retina 608 

The  Aqueous  Humor        ---------  610 

The  Crystalline  Lens --610 

The  Vitreous  Humor -  611 

The  Ear 612 

The  External  Ear     -  612 

The  Middle  Ear 616 

The  Internal  Ear -        -        -  621 

The  Organ  of  Taste 628 

The  Skin  and  its  Appendages  -         -        -         -         -         -.-        -  628 

The  Dermis                                                                                             -         -  629 

The  Epidermis  631 

The  Sweat  Glands -  633 

The  Sebaceous  Glands 634 

The  Hairs ...  636 

The  Nails 640 


LIST    OF    ILLUSTRATIONS. 


[Those  marked  with  an  asterisk  are  by  the  author.  The  names  opposite  the  others  indicate  the 
authorities  from  which  they  have  been  obtained.  When  the  illustrations  differ  from  the  original  draw- 
ings they  have  been  altered  by  the  author  or  by  Dr.  Schmidt.] 

FIG. 

1  Monas  crepusculum.* 

2  Vibrios.* 

3  Diagram  of  a  typical  organic  cell.* 

4  Trachelomonas  volvocina,  from  stagnant  water.* 

5  Protococcus,  from  damp  pavements,  multiplying  by  division.* 

6  Ciliated  epithelial  cell.* 

7  Progressive  division  or  segmentation  of  the  yolk  in  the  human  egg.* 

8  Process  of  multiplication  of  cartilage  cells.* 

9  Process  of  development  of  an  organic  cell  from  a  granule.* 

10  Three  secreting  cells  from  the  submaxillary  salivary  gland.* 

11  A  lymph  corpuscle.* 

12  Epithelial  cells  of  a  serous  membrane.* 

13  Exhibits  the  progressive  development  of  the  epidermis.* 

14  Mode  of  development,  from  below  upward,  of  columnar  epithelial  cells.* 
1.5  Mode  of  development  of  unstriated  muscular  fibre.* 

16  Nerve  cell* 

17  Mode  of  development  of  capillary  vessels  from  cells.* 

18  Development  of  striated  muscular  fibre,  from  cells.* 

19  Development  of  fibrous  tissue.* 

20  Longitudinal  section  of  the  proximal  extremity  of  the  femur.     Ibbotson. 

21  Horizontal  section  of  the  condyles  of  the  femur.     Ibid. 

22  Vertical  section,  antero-posteriorly,  of  the  calcaneum.     Ibid. 

23  Transverse  section  of  the  shaft  of  a  phalanx.* 

24  Transverse  section  of  bone  from  the  shaft  of  the  femur.* 

25  An  osseous  lacuna.* 

26  Thin  plate  from  the  ethmoid  bone.* 

27  Development  of  the  femur.     Wilhelm. 

28  Development  of  the  vertebrae.     Quain  Sf  Sharpey. 

29  Development  of  the  epiphyses  to  the  vertebrae.     Ibid. 

30  External  view  of  the  occipital  bone.     Wilson. 

31  Internal  view  of  the  occipital  bone.     Ibid. 

32  Front  view  of  the  sphenoid  bone.     Schmidt. 

(xv) 


xvi  LIST   OF  ILLUSTRATIONS. 

FIG. 

33  Upper  view  of  the  sphenoid  bone.* 

34  Upper  view  of  the  ethmoid  bone.     Wilson. 

35  External  view  of  the  frontal  bone.     Ibid. 

36  Internal  view  of  the  frontal  bone.     Ibid. 

37  Outer  view  of  the  left  parietal  bone.     Ibid. 

38  Inner  view  of  the  left  parietal  bone.     Ibid. 

39  External  view  of  the  temporal  bone  of  the  right  side.* 

40  Internal  view  of  the  temporal  bone  of  the  left  side.     Packard. 

41  Inferior  view  of  the  left  temporal  bone.* 

42  Internal  view  of  the  base  of  the  cranium  of  the  left  side.     Schmidt. 

43  External  view  of  the  base  of  the  skull,  right  side.    Ibid. 

44  Antero-posterior  section  of  the  cranium.* 

45  Horizontal  section  of  the  cranium.* 

46  Transverse  section  through  the  front  of  the  cranium.* 

47  Transverse  section  in  advance  of  the  middle  of  the  cranium.* 

48  Transverse  section  through  the  middle  of  the  cranium.* 

49  Transverse  section  posterior  to  the  middle  of  the  cranium.* 

50  Two  pieces  of  the  temporal  bone.     Quain  $•  Sliarpey. 

51  Superior  maxillary  bone  of  the  left  side.     Schmidt. 

52  Superior  maxillary  bone  of  the  left  side.     Ibid. 

53  Posterior  view  of  the  right  palate  bone.     Wilson. 

54  Exterior  view  of  the  right  palate  bone.     Ibid. 

55  External  view  of  the  right  lachrymal  bone.     Ibid. 

56  Anterior  view  of  the  left  nasal  bone.     Ibid. 

57  External  view  of  the  right  turbinated  bone.     Homer. 

58  Left  side  of  the  vomer.     Wilson. 

59  Outer  view  of  the  right  malar  bone.     Ibid. 

60  Inferior  maxillary  bone.     Ibid. 

61  Yertical  section  of  the  articulation  of  the  lower  jaw.     Ibid. 

62  External  view  of  the  temporo-maxillary  articulation.     Ibid. 

63  The  skull,  seen  partly  in  front  and  on  the  right  side.      Wilhelm. 

64  View  of  the  right  side  of  a  portion  of  the  face  and  cranium.     Schmidt. 

65  Yiew  of  the  right  half  of  the  base  of  the  skull.     Ibid. 

66  Yertical  section  of  the  face.     Ibid. 

67  Yiew  of  the  outer  wall  of  the  right  nasal  fossa.     Ibid. 

68  The  hyoid  bone.     Wilson. 

69  The  vertebral  column.     Morton. 

70  Side  view  of  a  dorsal  vertebra.     Wilson. 

71  Upper  view  of  a  cervical  vertebra.     Ibid. 

72  Upper  view  of  the  atlas.     Ibid. 

73  Side  view  of  the  axis.     Ibid. 

74  Side  view  of  a  dorsal  vertebra.     Ibid. 

75  Side  view  of  a  lumbar  vertebra.     Ibid. 

76  Front  view  of  the  sacrum.     Ibid. 

77  Back  view  of  the  sacrum.     Ibid. 

78  Posterior  view  of  the  coccyx.    Morton. 


LIST   OF   ILLUSTRATIONS.  xvii 

FIG. 

79  Development  of  the  vertebrae.     Quain  Sf  Sharpey. 

80  Development  of  the  epiphyses  to  the  vertebrae.     Ibid. 

81  Upper  view  of  a  lumbar  vertebra.     Ibid. 

82  Yertical  section  of  two  lumbar  vertebrae.     Ibid. 

83  Three  vertebral  arches  removed  from  as  many  dorsal  vertebrae.     Wilson. 

84  Portion  of  the  occipital  bone,  with  the  atlas  and  axis.    Ibid. 

85  Three  dorsal  vertebras.     Ibid. 

86  Portion  of  the  cranium  and  of  the  atlas  and  axis.     Ibid. 

87  Bodies  of  three  dorsal  vertebrae.     Ibid. 

88  Portion  of  the  occipital  bone,  with  the  atlas  and  axis.    Ibid. 

89  Portion  of  the  occipital  bone  and  the  upper  three  cervical  vertebrae.  Ibid. 

90  Portion  of  the  skull,  the  atlas,  and  axis.     Ibid. 

91  Front  view  of  the  thorax.     Ibid. 

92  Anterior  view  of  three  dorsal  vertebrae  and  their  articulation  with  the 

ribs.    Ibid. 

93  Posterior  view  of  four  dorsal  vertebrae  and  their  articulation  with  the 

ribs.     Ibid. 

94  Front  view  of  the  thorax.     Ibid. 

95  Inner  view  of  the  left  hip  or  innominate  bone.     Schmidt. 

96  Outer  view  of  the  left  hip  or  innominate  bone.     Wilson. 

97  Ligaments  of  the  pelvis  and  hip  joint.     Ibid. 

98  Ligaments  of  the  pelvis  and  hip  joint.     Ibid. 

99  Front  view  of  a  female  pelvis.     Ibid. 

100  Clavicle  of  the  right  side.     Ibid. 

101  The  scapula  of  the  left  side.     Ibid. 

102  Anterior  view  of  the  scapula.     Ibid. 

103  Humerus  of  the  left  side.     Ibid. 

104  The  two  bones  of  the  left  forearm.     Ibid. 

105  Bones  of  the  carpus.     Ibid. 

106  The  left  hand.    Ibid. 

107  Sterno- clavicular,  costo-clavicular,  and  costo-sternal  articulations.     Ibid. 

108  Scapulo-clavicular  and  scapulo-humeral  articulations.     Ibid. 

109  The  elbow  joint.    Ibid. 

110  The  same  elbow  joint.     Ibid. 

111  Ligaments  of  the  wrist  and  hand.     Ibid. 

112  Femur  of  the  right  side.     Ibid. 

113  Patella  of  the  right  side.     Ibid. 

114  Tibia  and  fibula  of  the  left  leg.     Ibid. 

115  Tibia  and  fibula  of  the  right  leg.     Ibid. 

11 6  Dorsal  surface  of  the  right  foot.     Ibid. 

117  Sole  of  the  left  foot.    Ibid. 

118  Ligaments  of  the  hip.     Ibid. 

119  The  right  knee  joint.     Ibid. 

120  Front  view  of  the  right  knee  joint.     Ibid. 

121  Longitudinal  section  of  the  left  knee  joint.     Ibid. 

122  Posterior  view  of  the  inferior  tibio-fibular  and  ankle  joints.     Ibid. 


LIST   OF   ILLUSTRATIONS. 

FIG. 

123  External  view  of  the  right  ankle  joint.     Wilson. 

124  Internal  view  of  the  ankle  joint.     Ibid. 

125  Ligaments  of  the  sole  of  the  foot.     Ibid. 

126  Example  of  fibrous  tissue.* 

127  Examples  of  fibrous  tissue.* 

128  Portion  of  connective  tissue.* 

129  Fibrous  tissue.* 

130  Portion  of  connective  tissue.* 

131  Crossing  bands  of  fibrous  tissue.* 

132  Cartilage.* 

133  Vertical  section  of  articular  cartilage.* 

134  Section  of  costal  cartilage.* 

135  Section  of  costal  cartilage.* 

136  Section  of  fibro-cartilage  from  the  auricle  of  the  ear.* 

137  Elastic  tissue.* 

138  Elastic  tissue.     Kolliker. 

139  Elastic  tissue.     Ibid. 

140  Adipose  tissue,  with  connective  tissue.* 

141  Transverse  section  of  the  lower  end  of  the  ulno-carpal  flexor.* 

142  Transverse  section  of  a  muscular  fasciculus.* 

143  Two  portions  of  a  muscular  fasciculus.* 

144  Two  muscular  fibres.* 

145  Fibrils  from  a  muscular  fibre  of  the  axolotl.     Kolliker. 

146  A  muscular  fibre  of  a  salamander.* 

147  Muscles  of  the  head  and  neck.     Sappey. 

148  Yiew  of  the  interior  part  of  the  left  side  of  the  face.    Jamain. 

149  Yiew  of  the  temporal  muscle.    After  Bonamy  §•  Beau,  Morton. 

150  Inner  part  of  the  ramus  of  the  lower  jaw.     Wilson. 

151  Front  view  of  the  muscles  of  the  neck.     Ibid. 

152  Deep  muscles  of  the  front  of  the  neck.     Morton. 

153  Muscles  of  the  front  of  the  thorax  and  abdomen.     Wilson. 

154  Muscles  of  the  back.     Ibid. 

155  Extensor  muscles  of  the  back.     Ibid. 

156  Muscles  of  the  front  of  the  trunk.     Ibid* 

157  Yiew  of  the  left  side  of  the  abdomen.     Ibid. 

158  Yiew  of  the  inguinal  canal.     Sappey. 

159  Inferior  view  of  the  diaphragm.     Wilson. 

160  Muscles  of  the  back  of  the  scapula.     After  Bonamy  §•  Beau,  Morton. 

161  Muscles  of  the  front  of  the  scapula.     Ibid. 

162  The  deltoid  muscle.     Ibid. 

163  Muscles  of  the  fore  part  of  the  arm.     Wilson. 

164  Yiew  of  the  triceps  extensor,  on  the  back  of  the  right  arm.     Ibid. 

165  Superficial  muscles  of  the  front  of  the  forearm.     Ibid. 

166  Deep  muscles  of  the  front  of  the  forearm.     Ibid. 

167  Metacarpal  and  phalangial  bones  of  the  fingers,  with  their  tendons  and 

ligaments.     Quain  §•  Sharp ey. 


LIST   OF   ILLUSTRATIONS.  xix 

FIG. 

168  Muscles  of  the  back  of  the  forearm.    Wilson. 

169  Deep  muscles  of  the  back  of  the  forearm.     Ibid. 

170  Muscles  of  the  palmar  surface  of  the  hand.     Ibid. 

171  Yiew  of  the  inguinal  canal.     Sappey. 

172  Muscles  of  the  buttock.     Wilson. 

173  Muscles  of  the  iliac  region  and  front  of  the  thigh.     Ibid. 

174  Muscles  of  the  back  of  the  right  buttock  and  thigh.     Ibid. 

175  Muscles  of  the  front  of  the  leg  and  back  of  the  foot.     Ibid. 

176  Superficial  muscles  on  the  back  of  the  right  leg.     Ibid. 

177  Deep  muscles  of  the  back  of  the  leg.     Ibid. 

178  Muscles  of  the  sole  of  the  foot.     Ibid. 

179  Deep  muscles  of  the  sole.     Ibid. 

180  Diagram  exibiting  the  relative  position  of  the  common  anatomical  ele- 

ments of  serous  and  mucous  membranes,  the  glands,  the  lungs,  and  the 
skin.* 

181  Squamous  epithelium.* 

182  Pavement  epithelium.* 

183  Polyhedral  epithelium.* 

184  Diagram  of  a  vertical  section  of  mucous  membrane  of  the  small  intes- 

tine.* 

185  Diagram  of  a  vertical  section  of  the  bronchial  mucous  membrane.* 

186  Diagram  of  a  section  of  the  mucous  membrane  of  the  mouth.* 

187  Diagram  exhibiting  the  relation  of  a  serous  membrane,  the  pleura,  to  the 

organ  it  invests  and  the  cavity  it  lines.* 

188  Diagram  of  two  simple  tubular  glands.* 

189  Simple  gland  dilated  into  a  pouch.* 

190  Glands  rendered  slightly  complex  by  division  at  bottom.* 

191  Increase  of  complexity  of  glands.* 

192  A  tubular  gland.* 

193  Gland  of  complex  form.* 

194  Gland  of  complex  form.* 

195  Gland  of  complex  character.* 

196  A  racemose  gland.* 

197  Unstriated  muscular  fibre.* 

198  Vertical  section  of  the  face  and  neck,  through  the  median  line,  antero- 

posteriorly,  exposing  to  view  the  nose,  mouth,  pharynx  and  larynx. 
Sappey. 

199  Section  of  a  follicular  gland  from  the  root  of  the  tongue.     Kolliker. 

200  Posterior  view  of  the  muscles  of  the  palate  and  fauces.     After  Bonamy 

Sf  Beau,  Morton. 

201  Yiew  of  the  upper  surface  of  the  tongue.     Sappey. 

202  Diagram  of  the  papillae  of  the  tongue.* 

203  Papillae  of  the  tongue.* 

204  Side  view  of  the  muscles  of  the  tongue.   After  Bonamy  $•  Beau,  Morton. 

205  Upper  and  lower  permanent  teeth,  exterior  view.     Schmidt. 

206  Lateral  views  of  same.    Ibid. 


xx  LIST   OF   ILLUSTRATIONS. 

FIG. 

207  Temporary  teeth  of  one  side.     Schmidt. 

208  Vertical  section  of  a  molar  tooth.* 

209  Vertical  section  of  the  fang  of  a  canine  tooth.* 

210  Section  of  dentine.* 

211  Three  enamel  columns.* 

212  Section  of  enamel.* 

21 3  Diagram  of  the  mode  of  development  of  the  teeth.  After  Goodsir,  Kolliker. 

214  Posterior  view  of  the  muscles  of  the  pharynx.     Wilson. 

215  Side  view  of  the  muscles  of  the  pharynx.     Ibid. 

216  Cavity  of  the  abdomen  laid  open,  with  the  viscera  retained  in  their  relative 

position.     Ibid. 

217  Diagram  of  the  reflections  of  the  peritoneum  in  a  vertical  section  of  the 

abdomen.* 

218  The  stomach  and  intestines.     Schmidt. 

219  Wrinkled  or  rugous  surface  of  the  mucous  membrane  of  the  stomach. 

Sappey. 

220  Mammillae  of  the  mucous  membrane  of  the  stomach.     Ibid. 

221  Small  portion  of  the  mucous  membrane  of  the  stomach,  with  the  imbedded 

gastric  glands.* 

222  A  gastric  gland.* 

223  Small  portion  of  the  mucous  membrane  from  the  upper  part  of  the  jeju- 

num.* 

224  Portion  of  mucous  membrane  from  the  ileum.* 

225  Diagram  of  the  structure  of  the  mucous  membrane  of  the  ileum.* 

226  Portion  of  the  duodenum.     Sappey. 

227  A  vertical  section  of  the  duodenum.* 

228  Portion  of  the  mucous  membrane  from  the  upper  part  of  the  ileum. 

Sappey. 

229  Portion  of  the  ileum.     Ibid. 

230  The  caecum  laid  open,  to  expose  the  ileo-caecal  valve.     Morton. 

231  Section  of  the  mucous  membrane  of  the  colon.* 

232  Inferior  surface  of  the  liver.* 

233  Portion  of  the  liver  of  the  hog.     After  Kiernan,  Kolliker. 

234  Portion  of  the  liver  of  the  hog.     Ibid. 

235  Section  of  several  lobules  of  the  liver  of  the  rabbit.     Kolliker. 

236  Polyhedral  epithelium.* 

237  Diagram  representing  the  section  of  a  lobule  of  the  liver.* 

238  Diagram  representing  a  transverse  section  of  one  of  the  cords  of  the 

hepatic  cell-net* 

239  Transverse  section  of  the  walls  of  the  aorta.    Kolliker. 

240  Elastic  tissue  from  the  middle  coat  of  the  popliteal  artery.     Ibid. 

241  Unstriated  muscular  fibres  from  the  middle  coat  of  the  arteries.     Ibid. 

242  Diagrams  exhibiting  the  arrangement  of  the  valves  of  veins.     Morton. 

243  A  small  artery  magnified.     Kolliker. 

244  Red  blood  corpuscles.* 

245  Front  view  of  the  heart.     Quain  Sf  Sharpey. 


LIST   OF   ILLUSTRATIONS.  xxi 

FIG. 

246  Posterior  or  lower  surface  of  the  heart.     Quain  $•  Sliarpley. 

247  View  of  the  heart,  with  the  anterior  portions  of  ihe  ventricles  removed. 

Schmidt. 

248  Striated  muscular  tissue  of  the  heart.* 

249  The  aorta.     Bourgery. 

250  Left  common  carotid  dividing  into  the  external  and  internal  carotid  arte- 

ries.    Ibid. 

251  The  external  carotid  artery  and  its  branches.     Ibid. 

252  Internal  maxillary  artery.     Ibid. 

253  Arteries  of  the  interior  of  the  cranium.     Ibid. 

254  View  of  the  axillary  artery.     Schmidt. 

255  View  of  the  axillary  and  brachial  artery.     Ibid. 

256  Arteries  of  the  forearm.     Bourgery. 

257  Arteries  of  the  hand ;  palmar  surface.     Ibid. 

258  The  aorta.     Ibid. 

259  Distribution  of  the  cceliac  artery.      Wilson. 

260  Distribution  of  the  superior  mesenteric  artery.    Jamain. 

261  Distribution  of  the  inferior  mesenteric  artery.     Ibid. 

262  Yiew  of  the  left  side  of  the  pelvis,  the  bladder,  uterus,  vagina,  and  rec- 

tum.    Ibid. 

263  Yiew  of  the  perineum,  exhibiting  the  distribution  of  the  internal  pudic 

artery.     Bourgery. 

264  Arteries  of  the  front  of  the  thigh.     Jamain. 

265  Arteries  of  the  back  of  the  thigh.     Ibid. 

266  Arteries  of  the  front  of  the  leg.     Ibid. 

267  Arteries  of  the  back  of  the  leg.     Ibid. 

268  Arteries  of  the  sole  of  the  foot.     Ibid. 

269  Yeins  of  the  thorax  and  abdomen.     Bourgery. 

270  Yeins  of  the  head  and  neck.         Ibid. 

271  Sinuses  at  the  base  of  the  cranium.     Schmidt. 

272  Vertical  section  of  the  skull.     Ibid. 

273  Superficial  veins  of  the  upper  extremity.     Ibid. 

274  Yeins  of  the  thorax  and  abdomen.     Bourgery. 

275  The  portal  system  of  veins.     Quain  fy  SJiarpey. 

276  Superficial  veins  of  the  back  of  the  leg.     Bourgery. 

277  Superficial  veins  of  the  inner  part  of  the  lower  extremity.     Ibid. 

278  Lymphatic  capillary  net-work  of  the  skin  of  the  ear.     Sappey. 

279  Yiew  of  the  great  lymphatic  trunks.     Bourgery. 

280  Lymphatics  of  the  head  and  neck.     Ibid. 

281  Cartilages  of  the  larynx.     Quain  fy  Sharpey. 

282  Yiew  of  the  vocal  membrane.* 

283  Muscles  of  the  larynx.* 

284  Vertical  section  of  the  face  and  neck,  through  the  median  line  antero- 

posteriorly,  exposing  to  view  the  nose,  mouth,  pharynx  and  larynx. 
Sappey. 

285  Front  of  the  larynx,  trachea  and  bronchi,  and  back  of  the  same.     Rich- 

ardson. 


xxii  LIST   OF  ILLUSTRATIONS. 

FIG. 

286  The  trachea,  lungs  and  heart.     Bourgery. 

287  Diagram  of  the  two  primary  lobules  of  the  lungs.* 

288  Portion  of  the  thyroid  body  in  section.     Kolliker. 

289  One  lobe  of  the  thymus  body,  with  its  cavity  laid  open,  and  exhibiting  the 

lobular  recesses.  *  Ibid. 

290  Section  of  a  lobule  of  the  thymus  body.     Ibid. 

291  Longitudinal  section  of  a  kidney.* 

292  Diagram  of  the  structure  of  the  kidneys.* 

293  Section  of  the  cortical  substance  of  a  supra-renal  body.     Kolliker. 

294  Cells  from  the  supra-renal  body.     Ibid. 

295  Testicle,  with  the  vaginal  tunic  laid  open.     Quain  $•  SJiarpey. 

296  Transverse  section  of  the  testicle.     Kolliker. 

297  Testicle,  deprived  of  its  tunics.     After  Arnold,  Kolliker. 

298  Portion  of  a  seminiferous  tubule.     Kolliker. 

299  Posterior  view  of  the  fundus  of  the  bladder.     Cruveilhier. 

300  Spermatozoids.     Kolliker. 

301  Transverse  section  of  the  penis.     After  Weber,  Morton. 

302  Vertical  section  of  the  penis  and  bladder.* 

303  Part  of  the  bladder  and  penis,  witfr  the  urethra  laid  open  from  above. 

Wilson. 

304  Sketch  of  the  uterus  and  its  appendages.     Ibid. 

305  Section  of  the  uterus  antero-posteriorly,  and  section  of  the  uterus  from  side 

to  side.* 

306  Transverse  section  of  an  ovary.     Kolliker. 

307  Human  ovum.     Ibid. 

308  Two  corpora  lutea.     Ibid. 

309  Ovary,  parovarium,  and  Fallopian  tube  of  the  left  side.* 

310  Section  of  female  pelvis,  from  before  backward.     Schmidt. 

311  External  organs  of  generation.* 

312  Side  view  of  the  male  pelvis  and  its  contents.     Wilson. 

313  View  of  the  perineum.     Bourgery. 

314  Several  small  lobules  of  the  mammary  gland  of  a  pregnant  woman.   After 

Langer,  Kolliker. 

315  Diagram,  exhibiting  the   course  of  a  lactiferous  duct.      After   Cooper, 

Morton. 

316  Corpuscles  observed  in  milk.    Kolliker. 

317  Nerve  fibres  of  the  white  substance  of  the  cerebrum.* 

318  Portion  of  gray  substance,  from  the  exterior  of  the  cerebellum.* 

319  Large  nerve  cells  from  the  anterior  horns  of  the  gray  substance  of  the 

spinal  cord.    Kolliker. 

320  Transverse  section  of  the  small  sciatic  nerve.     Ibid. 

321  Mode  of  anastomosis  and  branching  of  nerves.* 

322  Structure  of  nerve  fibres.* 

323  Pacinian  corpuscles.* 

324  Elements  of  the  sympathetic  system.     Kolliker. 

325  Nerve  cells  from  the  semilunar  ganglion  of  the  trigeminal  nerve.     Ibid. 


LIST   OF   ILLUSTRATIONS.  xxjii 


FIG. 


326  Base  of  the  brain.     After  Hirsclifeld,  Sappey. 

327  Transverse  section  of  the  hemispheres  of  the  cerebrum  on  a  level  with 

the  corpus  callosum.* 

328  Section  of  the  brain  along  the  great  longitudinal  fissure.     After  Hirsch- 

feld,  Sappey. 

329  Transverse  section  of  the  cerebral  hemispheres,  the  corpus  callosum  re- 

moved, and  the  lateral  ventricles  exposed.* 

330  Striated  bodies,   thalami,  quadrigeminal  body,  and  cerebellum.     After 

Hirsclifeld,  Sappey. 

331  Segment  of  the  spinal  cord.* 

332  Oculo-motor  and  abducent  nerve.    After  Hirschfeld,  Sappey. 

333  Trifacial  nerve.     Ibid. 

334  Ophthalmic  ganglion,  the  outer  part  of  the  right  orbit  removed.   Ibid. 

335  Superior  maxillary  nerve,  the  external  wall  of  the  left  orbit  and  of  the 

superior  maxillary  bone  removed.    Ibid. 

336  View  of  the  spheno-palatine  ganglion,  the  outer  wall  of  the  left  nasal 

cavity,  and  the  olfactory  nerve.     Ibid. 

337  Distribution  of  the  inferior  maxillary  nerve.     Ibid. 

338  The  facial  nerve.     Ibid. 

339  The  last  four  cerebral  nerves,  the  facial  nerve,  the  sympathetic,  and  the 

upper  two  cervical  nerves.     Ibid. 

340  The  pneumogastric  nerve.     Ibid. 

341  The  bracial  plexus.     Ibid. 

342  Cutaneous  nerves  of  the  upper  extremity.     Ibid. 

343  The  same.     Ibid. 

344  External  cutaneous,  median,  ulnar,  and  musculo-spiral  nerves.     Ibid. 

345  The  same.     Ibid. 

346  Cutaneous  nerves  of  the  front  of  the  thigh.     Ibid. 

347  Lumbar  plexus  and  its  branches.     Ibid. 

348  External  popliteal  nerve  and  its  branches.     Ibid. 

349  Popliteal  nerves.     Ibid. 

350  Partition  of  the  nose.    Sappey. 

351  Cartilages  of  the  nose.     Ibid. 

352  Outer  wall  of  the  left  nasal  cavity.     Ibid. 

353  Nerves  of  the  partition  of  the  nose.     Ibid. 

354  The  left  eyelid  and  lachrymal  gland,  turned  forward  and  inward  so  as  to 

see  their  inner  surface.     Ibid. 

355  The  left  eye,  with  a  portion  of  the  eyelids  removed,  to  exhibit  the  lachry- 

mal canals  and  sac.     Ibid. 

356  Muscles  of  the  eye.    Morton. 

357  Vertical  section  antero-posteriorly  of  the  eyeball.     Sappey. 

358  The  choroidea  and  iris.     Ibid. 

359  Veins  of  the  choroidea  and  iris.     Ibid. 

360  View  from  behind  of  the  anterior  part  of  the  eyeball.     Ibid. 

361  The  same  view,  with  the  crystalline  lens  and  retina  removed.     Ibid. 

362  Segment  of  the  choroidea  and  iris,  seen  on  its  inner  surface.     Ibid. 


xxiv  LIST  OF   ILLUSTRATIONS. 


FIG. 


363  Arteries  of  the  iris.    Sappey. 

364  The  eyeball,  with  the  sclerotica,  cornea,  choroidea,  and  iris  removed.    Ibid. 

365  Retina,  seen  on  its  posterior  inner  surface.     Ibid. 

366  The  crystalline  lens.     Ibid. 

367  Crystalline  lens,  breaking  up  into  segments.     Ibid. 

368  Segment  of  the  crystalline  lens.     Ibid. 

369  The  auricle.     Ibid. 

370  General  view  of  the  ear,  right  side,  laid  open  from  the  front.     Ibid. 

371  Cavity  of  the  tympanum  and  mastoid  sinuses.     Ibid. 

372  Small  bones  of  the  ear.     Ibid. 

373  The  internal  ear,  consisting  of  the  labyrinth  and  internal  auditory  meatus, 

laid  open.     Ibid. 

374  Internal  ear  laid  open.     Ibid. 

375  Nerves  of  the  vestibule  and  semicircular  canals.     Ibid. 

376  The  cochlea,  laid  open,  its  summit  turned  upward.     Ibid. 

377  The  cochlea,  laid  open,  and  viewed  from  its  summit  toward  the  base. 

Ibid. 

378  Distribution  of  the  cochlear  nerve.     Ibid- 

379  Vertical  section  of  the  skin  of  the  forefinger  across  two  of  the  ridges  of 

the  surface.* 

380  Scurf  from  the  leg.* 

381  Fragment  of  dandruff  from  the  head.* 

382  Sebaceous  glands  opening  into  the  mouth  of  a  hair  follicle.    Todd  $•  Bow- 

man. 

383  A  large  sebaceous  gland  from  the  nose.     Kolliker. 

384  Sebaceous  matter,  from  one  of  the  sebaceous  glands  of  the  nose.* 

385  Structure  of  the  sebaceous  glands.     Kolliker. 

386  Portion  of  the  shaft  of  a  light  hair.     Ibid. 

387  Portion  of  a  hair  from  the  outer  part  of  the  thigh.* 

388  Root  of  a  hair  lodged  within  its  follicle.     Kolliker. 

389  Diagram  of  structure  of  the  root  of  a  hair  within  its  follicle.* 

390  Matrix  of  the  nail.     Sappey. 

391  Under  surface  of  the  nail.     Ibid. 

392  Vertical  section  of  the  end  of  a  finger.     Ibid. 


AN 


ELEMENTARY  TREATISE 


HUMAN    ANATOMY 


CHAPTER  I. 

INTRODUCTION. 

THE  word  Anat'omy  means  dissection ;  but  it  has  become  to  be  ap- 
plied to  the  study  of  the  physical  structure  of  organized  bodies.  The 
word  is  variously  modified,  according  to  its  application ;  and  thus  we 
have  vegetable  anatomy,  comparative  anatomy,  human  anatomy,  patho- 
logical anatomy,  etc. 

Hu/man  anat'omy,  the  special  object  of  our  attention,  may  be  sub- 
divided into  general,  special,  and  topographical  anatomy. 

Gen/eral  anat'omy  treats,  in  common,  of  the  physical  elements  of  struc- 
ture of  the  various  organs  of  the  body.  It  is  frequently  named  Micro- 
scopic anatomy,  from  the  necessity  of  employing  the  microscope  in 
its  study.  The  term  Histology,  from  the  Greek  I<TTOS,  the  organic  struc- 
ture, and  Ao^>^,  a  description,  is  also  applied  to  it. 

Special  or  Descriptive  anat'omy  treats  of  the  properties,  such  as  form, 
color,  size,  and  situation  of  the  organs  of  the  body  arranged  into  sys- 
tems ;  and  thus  we  have  the  anatomy  of  the  bones,  of  the  muscles,  etc. 

Topographical  anat'omy  treats  of  the  relative  position  of  organs  in 
particular  regions  of  the  body.  Thus,  the  topographical  anatomy  of  the 
groin  refers  to  all  the  organs  in  this  region.  It  is  also  called  Surgical 
anatomy,  from  its  importance  in  surgery. 

In  commencing  with  the  study  of  human  anatomy,  the  author  thinks  it 
not  amiss  in  directing  the  student  to  take  a  cursory  glance  at  the  general 
structure,  characteristic  phenomena,  and  conditions  of  existence  of  living 
bodies,  of  which  man  constitutes  the  highest  or  most  complex  type. 

According  to  the  present  state  of  chemical  knowledge,  about  sixty 

2  (17) 


18  INTRODUCTION. 

different  kinds  of  matter,  the  so-called  simple  or  ultimate  elements,  enter 
into  the  composition  of  the  earth.  The  phrase  "  kinds  of  matter"  is 
expressive  of  the  idea  of  the  ponderable  agencies  of  nature  which  are 
not  reducible  to  a  simpler  condition  with  all  the  aids  of  modern  science, 
are  incapable  of  conversion  into  one  another,  and  are  indestructible. 

All  the  material  masses  or  bodies  of  the  earth  are  divisible  into  two 
great  groups — mineral  bodies  and  organized  bodies.  The  former  are 
known  as  minerals,  and  comprehend  the  rocks,  stones,  ores,  soils,  water, 
air,  and  gasses ;  the  latter  are  known  as  plants  and  animals,  including 
all  their  parts. 

Mineral  bodies,  in  contradistinction  to  organized  bodies,  are  also 
called  unorganized.  They  are  homogeneous  in  structure ;  and,  under 
ordinary  circumstances,  either  have  no  definite  form,  expressed  by  the 
term  amorphous,  or  they  are  crystalline ;  that  is  to  say,  they  are  of 
regular  form,  defined  by  plane  surfaces  and  sharp  angles.  Under  special 
circumstances,  it  is  probable  that  all  mineral  bodies  may  assume  a  crys- 
talline form.  Thus,  water  and  mercury,  ordinarily  liquid,  at  lower  tem- 
peratures become  crystalline  solids ;  and  even  certain  aeriform  fluids, 
such  as  carbonic  acid  or  nitrous  oxide,  under  the  combined  influence 
of  high  pressure  and  intense  cold,  assume  the  condition  of  crystalline 
masses. 

Organized  bodies  are  composed  of  a  few  simple  physical  elements, 
which  may  be  arranged  as  follows  : — 

1.  Homogeneous  liquid,  and  its  transitions  toward  a  solid  condition. 

2.  Homogeneous  granules. 

3.  Homogeneous  filaments. 

4.  Homogeneous  membrane. 

Every  organized  body  originates  in  a  homogeneous  liquid,  the  most 
complex  as  well  as  the  most  simple ;  and  every  one  starts  into  definite 
existence  as  a  homogeneous  granule,  invisible  except 
with  the  aid  of  the  microscope.  The  granule  is  the 
first  appreciable  step  in  the  production  of  the  seed  of 
plants,  and  of  the  egg  of  animals.  There  are  certain 
specific  living  beings,  which,  throughout  their  exist- 
ence, appear  to  consist  of  a  simple  granule ;  as,  for 
instance,  the  Monas  crepusculum,  represented  in  figure 
1.  This  measures  less  than  the  10,000th  of  an  inch  in 
CREPUSCCLUM.  diameter,  or  is  so  minute  that  500,000,000  may  be 

Highly  magnified. 

crowded  in  a  drop  of  water,  in  which  they  are  often 
observed  endowed  with  the  power  of  movement. 

Homogeneous  filaments  are  the  least  frequent  constituents  of  organized 
bodies.  They  constitute  the  vibrating  appendages  of  certain  microscopic 


INTRODUCTION.  19 

plants,  of  many  animalcules,  of  the  so-called  ciliated  cells  of  more  com- 
plex animals,  and  of  the  spermatozoids  of  the  male  seminal  liquid.  They 
also  appear  to  form  the  structure  of  areolar  tissue. 

Some  of  the  simplest  forms  of  specific  organic  life  consist,  apparently, 
of  mere  homogeneous  filaments  ;  as,  for  instance,  the 
various  species  of  Yibrio,  (figure  2,)  millions  of  which, 
endowed  with  the  power  of  movement,  may  be  observed 
in  any  organic  infusion  that  has  been  exposed  for  a  short 
time  to  the  air.  The  thin,  oil-like,  iridescent  film,  often 
seen  on  standing  water,  is  sometimes  composed  of  these 
living  homogeneous  filaments,  which,  decomposing  the 
rays  of  light  falling  on  them,  give  rise  to  the  charac- 
teristic  hues  of  the  rainbow. 

Homogeneous  membrane  is  an  important  solid  ele- 
ment  of  organized  structures,  and  is  mostly  the  con- 
taining part  when  the  other  elements  are  in  association  with  it. 

Organized  bodies  derive  their  materials  of  composition  from  the  min- 
eral world,  and  they  are  subject  to  the  control  of  the  same  laws  which 
govern  unorganized  bodies.  In  the  final  dissolution  of  organized  bodies, 
the  material  of  composition  again  reverts  to  the  mineral  world. 

Though  we  cannot  comprehend  the  idea  of  a  beginning  to  matter,  it 
is  nevertheless  conceivable  that  organized  bodies  may  have  had  a  definite 
commencement  or  origin  in  time.  Be  this  as  it  may,  the  nature  of  the 
origin  of  organized  bodies  in  time  is  involved  in  the  deepest  obscurity. 
If  the  view  of  many  cosmogenists  and  geologists  be  adopted,  that  the 
earth  was  once  in  a  highly  heated  or  incandescent  condition,  it  is  obvious 
such  a  state  would  have  been  incompatible  with  the  contemporaneous 
existence  of  organized  bodies  ;  and  it  would  follow,  of  necessity,  that 
they  were  subsequently  produced  or  introduced  when  the  temperature  of 
the  earth  was  reduced  to  the  condition  favorable  to  the  support  of  life. 

Philosophers  have  contended  that  the  simplest  forms  of  organized 
bodies  may  originate  directly  and  spontaneously  from  the  mineral  world, 
under  the  operation  of  ordinary  physical  causes.  Aside  from  the  im- 
portant fact  that  it  is  never  pretended  that  the  more  complex  plants  and 
animals  spring  into  existence  in  this  manner,  no  authentic  evidence  has 
yet  been  presented  to  us  that  microscopic  organisms  may  originate  spon- 
taneously ;  but,  on  the  contrary,  all  careful  investigations  and  well-con- 
ducted experiments  have  so  far  tended  to  refute  the  hypothesis. 

Organized  bodies  have  existed  for  incalculable  ages,  as  is  proved  by 
the  great  quantity  and  variety  of  their  remains,  which  extend  through 
an  enormous  depth  of  the  stratified  rocks  composing  the  surface  of  the 
earth.  Perhaps  a  more  remarkable  fact,  ascertained  in  the  exploration 


20  INTRODUCTION. 

of  the  latter,  is,  that  the  earliest  series  of  organized  bodies  became  ex- 
tinct to  give  place  to  a  new  series,  which  in  like  manner  subsequently 
became  extinct;  and  this  process  of  the  successive  origin  and  extinction 
of  races  or  series  of  species  has  continued  without  interruption  down  to 
the  present  period ;  from  which  it  is  probably  not  unsafe  to  infer  the 
ultimate  fate  of  the  existing  race  of  living  beings. 

For  convenience  in  study  and  easy  reference,  organized  bodies  are 
arranged  or  classified  in  some  system,  which  may  vary  according  to  our 
extent  of  knowledge  of  those  bodies.  Thus,  we  have  kingdoms,  classes, 
orders,  families,  genera,  species,  and  varieties,  each  division  exhibiting 
certain  characters  in  common,  by  which  its  relative  position  is  main- 
tained and  readily  perceived.  How  far  these  divisions  accord  with  any 
apparent  natural  plan,  is  a  subject  of  much  controversy. 

The  first  grand  division  of  organized  bodies  is  into  the  vegetable  and 
animal  kingdom,  or  into  plants  and  animals.  This  arrangement,  how- 
ever obvious  it  may  appear,  is  not  without  its  difficulties ;  for,  although 
the  higher  types  of  both  are  readily  distinguishable,  it  appears  to  be 
impossible,  in  the  present  condition  of  our  knowledge,  to  indicate  a 
positive  separation  between  the  lower  types ;  and  hence  we  find  natu- 
ralists classifying  the  simplest  forms  of  organized  bodies  indiscrimi- 
nately as  plants  or  animals. 

As  regards  the  subdivisions  of  the  vegetable  and  animal  kingdoms, 
though  there  is,  perhaps,  rather  more  concurrence  of  opinion,  yet  the 
attempt  to  define  positive  lines  of  separation  frequently  results  in  failure. 

In  accordance  with  the  systematic  labors  of  naturalists,  who  classify 
the  material  objects  of  nature,  a  species  of  organized  body  is  one  pos- 
sessing some  character  by  which  it  may  be  distinguished  from  another ; 
and  this  character  is  constant,  so  far  as  the  history  of  the  species  is 
known.  Varieties  are  founded  upon  distinctive  characters,  which,  as  is 
known  by  their  history,  are  temporary.  A  genus  consists  of  a  group  of 
species  possessing  some  structural  characters  in  common ;  and,  in  like 
manner,  a  group  of  genera  approaching  in  character  makes  a  family; 
and  thus  we  may  advance  to  the  starting-point  of  classification  into 
kingdoms. 

It  has  already  been  indicated  that  the  matter  of  mineral  or  unorgan- 
ized bodies,  and  that  of  organized  bodies,  is  the  same.  When,  however, 
we  speak  of  the  material  of  the  latter,  it  is  called  organic  matter,  in 
contradistinction  to  that  of  the  former,  which  is  called  inorganic  matter. 
In  other  words,  so  long  as  the  material  constitutes  mineral  or  unorgan- 
ized bodies,  it  is  inorganic  matter ;  but,  the  same  material  having  entered 
into  the  constitution  of  plants  and  animals,  or  organized  bodies,  is  then 
named  organic  matter. 


INTRODUCTION.  21 

The  derivation,  directly  or  indirectly,  of  organized  bodies  from  the 
inorganic  world,  is  termed  organization,  and  their  reduction  to  the  primi- 
tive condition,  disorganization,  or  decomposition. 

Of  the  sixty  ultimate  elements  of  the  earth,  less  than  a  third  enter  into 
the  composition  of  organized  bodies — seventeen  being  the  number  usually 
detected.  All  the  other  elements  of  nature  are  unorganizable,  or  inca- 
pable of  entering  into  the  perfect  constitution  of  plants  and  animals. 

Of  the  seventeen  organizable  elements,  Ox'ygen,  Hy'drogen,  Car'bon, 
and  Ni'trogen  are  so  universally  existent  in  plants  and  animals,  that 
they  are  viewed  as  the  necessary  or  essential  elements  of  every  organized 
body.  Coincident  with  this  highly  important  circumstance,  the  four  ele- 
ments mentioned  are  the  most  widely  diffused  and  abundant  in  nature. 

The  remaining  or  incidental  chemical  elements  of  organized  bodies, 
arranged  in  the  order  of  their  relative  importance,  or  frequency  and 
quantity,  are  as  follow:  Cal'cium,  Potas'sium,  So'dium,  Chlo'rine, 
Phos'phorus,  Sul'phur,  Silicon,  I'ron,  Magnesium,  Manganese', 
I'odine,  Flu/orine,  and  Bro'mine.  These  are  almost  never  found  in 
a  simple  condition,  but  are  in  combination  with  oxygen,  hydrogen,  and 
carbon,  and  with  one  another. 

The  ultimate  elements  by  union  constitute  the  proximate  chemical 
elements  of  organized  bodies,  which  are  those  entering  immediately  into 
the  structure  of  the  latter,  and  are  obtained  separately  by  the  simplest 
methods  of  analysis. 

The  proximate  elements  of  organized  bodies  are  numerous,  and  in 
many  instances  are  imperfectly  known.  They  may  be  divided  into  four 
groups,  as  follow :  1.  Nitrogenized  elements  peculiarly  organic,  such 
as  gluten  and  legumen  in  plants,  and  fibrin  and  albumen  in  animals. 
2.  Non-nitrogenized  elements  peculiarly  organic,  such  as  cellulose, 
starch,  sugar,  and  fats.  3.  Elements  not  peculiarly  organic,  as  water, 
carbonic  acid,  and  phosphate  of  lime.  4.  Elements  resulting  from  the 
disintegration  of  the  former  during  the  ordinary  vital  actions,  and  mostly 
found  in  the  secretions  and  excretions,  such  as  urea,  and  uric  acid  in 
animals. 

Through  a  variety  of  conditions — the  agency  of  disease,  spontaneously 
under  ordinary  circumstances  after  death,  or  aided  by  artificial  means — 
the  proximate  principles  are  resolved  into  a  vast  number  of  new  com- 
pounds, such  as  the  ordinary  fat  acids,  glycerin,  gelatin,  the  alcohols, 
ethers,  etc.  etc. 

Every  organized  body,  in  its  construction,  exhibits  a  series  of  phe- 
nomena called  those  of  life,  or  vital ;  and  hence,  when  an  organized 
body  presents  such  phenomena,  it  is  said  to  live,  or  possess  life  or 
vitality — which  terms  are  expressive  of  the  actions  peculiar  to,  or  ob- 


22  INTRODUCTION. 

served  only  in  association  with,  organic  forms.  Vital  phenomena,  or 
the  display  of  the  peculiar  actions  of  organized  bodies,  require  a  con- 
stant supply  of  the  elements  of  their  structure  in  a  liquid  state,  the  influ- 
ence of  the  air,  and  a  certain  range  of  temperature.  Without  these 
conditions  vital  activity  cannot  be  maintained ;  and  hence  these  condi- 
tions are  viewed  as  essential  to  life.  No  one  can  be  removed  with- 
out a  cessation  of  vital  action — often  forever — in  some  instances  only 
while  the  condition  is  absent.  Thus,  a  dried  seed  exhibits  no  vital 
activity,  but  may  do  so  when  the  essential  conditions  are  brought  to 
play  upon  it. 

Every  organized  body  must  have  lived  during  the  period  of  its  con- 
struction ;  but  it  may  be  subsequently  preserved  without  those  actions 
which  characterize  life — such  a  condition  being  distinguished  as  that  of 
death.  Thus,  the  timbers  of  our  buildings  and  the  clothes  we  wear 
were  once  living,  but  are  now  dead  organized  bodies. 

The  phenomena  which  characterize  life  are  as  follow :  the  origin  of 
the  organized  body  from  a  parent ;  its  successive  development  and 
growth  ;  the  processes  of  nutrition  and  assimilation  ;  the  combustion  of 
effete  particles  of  structure  ;  and  reproduction.  The  cessation  of  these 
phenomena  constitutes  death. 

All  living  bodies  proceed  from  parents,  whose  remotest  ancestry  can- 
not now  be  traced.  All  of  them  commence  in  or  start  from  the  con- 
dition of  a  homogeneous  liquid ;  and  the  first  defined  step  in  organization 
is  the  appearance  of  a  granule,  whose  form,  beneath  the  highest  powers 
of  the  microscope,  appears  to  be  spherical.  The  homogeneous  liquid 
in  which  living  bodies  originate  is  the  so-called  nutritive  matter.1  It 
contains  all  the  chemical  elements  of  structure  of  the  organized  bodies 
in  complete  solution. 

In  the  development  and  constitution  of  organized  bodies,  we  find  the 
four  ultimate  physical  elements,  previously  mentioned,  very  generally, 
more  or  less  associated  in  the  composition  of  a  common  characteristic 
structure  named  the  organic  cell.  All  organized  bodies,  except  such  as 
are  of  so  simple  a  nature  as  to  consist  alone  of  isolated  granules  or  fila- 
ments, are,  for  the  most  part,  composed  of  organic  cells  and  their  trans- 
formations. 

The  primitive  form  of  the  organic  cell,  as  represented  in  figure  3,  is 
that  of  a  spherical  vesicle  with  a  filamentary  appendage.  In  this  condi- 
tion, however,  the  organic  cell  is  not  often  observed,  for  generally  the 
filamentary  appendage  is  absent,  and  the  spherical  form  of  the  vesicle  is 
quickly  modified  after  its  development.  The  minute  being,  Trachelo- 

1  Plasma;  Blastema. 


INTRODUCTION  23 

monas  volvocina,  (figure  4,)  found  in  stagnant  water,  may  be  viewed  as  a 
specific  organized  body  consisting  of  a  single  typical  organic  cell.  The 
minute  plant,  Protococcus,  (figure  5,)  which  coats  damp  walls  and  pave- 

FIG.  3.  Fro.  4. 


TRACHELOMONAS  VOLVOCINA, 
DIAGRAM  OF  A  TYPICAL  FROM   STAGNANT    WATER. 

ORGANIC  CELL.  Highly  magnified. 

PROTOCOCCUS,  FROM  DAMP  PAVE- 
MENTS,   MULTIPLYING   BY  DIVI- 

ments,  in  shaded  places,  with  a  green  cover-  SIGN,  i,  a  simple  ceil;  2,  the 

ing,  consists  of  isolated  organic  cells  without         .  <—  ~  *£>£ 
the  filamentary  appendage.  4,  a  ceil  dividing  into  two. 

The  outer  portion  of  the  vesicle  of  the 

organic  cell,  or  the  cell  wall,  is  homogeneous  membrane.  The  cell  con- 
tents may  be  liquid,  semi-liquid,  granular,  or  filamentous.  Among  the 
cell  contents  very  generally  there  is  observed  a  second  and  much  smaller 
vesicle,  called  the  nu/cleus,1  which  though  liable  to  transformation  is 
much  less  so  than  the  containing  cell  The  wall  of  the  nucleus  is  also  of 
homogeneous  membrane,  and  its  contents  likewise  liquid,  semi-liquid,  or 
granular.  Occasionally  organic  cells  are  observed  with  several  nuclei. 
Among  the  nuclear  contents,  almost  always,  a  spherical  granule,  con- 
spicuous for  its  size,  may  be  distinguished  from  the  others,  and  this  is 
technically  called  the  nucle'olus. 

A  ciliated  epithelial  cell,  as  seen  in  figure  6,  from  the  mucous  mem- 
brane of  the  nasal  and  bronchial  passages,  pre- 
sents an  association  of  all  the  ultimate  physical 

elements  of  organized  bodies.  Thus  we  have  |H  CILIATED  EPITHELIAL 
homogeneous  membrane  in  the  cell  wall  and  nu-  CELL' from  the  pul" 

fag     mo  nary    mucous 

clear  wall ;  homogeneous  granules  and  liquid  in  B  membrane;  exhibit- 
the  cell  contents  ;  and  homogeneous  filaments  in  •  ing  the  granular  con- 

W         tents,  together  with 

the  vibrating  appendages.  the  nucleus,  and,  at 

In  plants,  organic  cells  are  generally  developed    the  "?***  frce  «tremity,  the 

'  .  °  /,-,...  vibrating  appendages  or  cilia. 

and  multiplied  through  division  and  subdivision 

of  the  contents  of  pre-existing  cells,  which  contents  at  the  same  time 
increase  in  bulk  or  grow  through  a  constant  supply  of  nutritive  matter, 
The  process  is  observed  in  the  germination  of  seeds  and  the  production 
of  the  stem,  leaves,  flowers,  and  fruit  of  plants.  In  the  simplest  of  vege- 

1  Cytoblast. 


24 


INTRODUCTION. 


FIG.  7. 


FIG.  8. 


tables,  such  as  the  Protococcus,  as  represented  in  figure  5,  it  is  the  mode 

of  reproduction  of  the  plant. 

This  method  of  production  and  multiplication  of 
organic  cells  is  also  observed  in  the  course  of  develop- 
ment of  the  embryo  from  the  egg.  After  the  latter  has 
been  fecundated  or  exposed  to  the  influence  of  the  male 
spermatic  liquid,  the  yolk  divides  into  two  spheres; 
these  subdivide  into  four,  and  this  process  continues 
until  the  yolk  is  reduced  to  the  condition  of  a  mass  of 
nucleated  cells,  as  represente  d  in  figure  T. 

Another  instance  in  which 
the  multiplication  of  cells 
through  division  of  the  con- 
tents is  strikingly  observed 
>  in  the  animal,  is  in  the  devel- 
opment of  the  cartilages.  In 
the  early  condition  of  carti- 
lage, it  consists  of  a  homo- 
geneous matrix  with  isolated  PROCESS  OF  MCLTIPL1CATIOJf 

nucleated      Cells     imbedded.    TILAGE  CELLS.    1,  simple  cartilage  cell 
,,     „,,  ,,.    ,       ,  ,     ,.    .      from  the  embryo;  2,  increase  of  car- 

^  These  multiply  through  divi-  tilage  cells  by  division  of  the  prl. 

Sion     and      form      groups     Of   niary  cell;  3,  4,  groups  of  cartilage 
»  .  cells,  from  an  adult  articular  carti- 

from   a  pair  to   twenty   or  l     ' 

more,  (figure  8,)  as  may  be 

seen  at  any  time  in  the  permanent  cartilages  of  the 

adult. 
0       Another  mode  of  production  of  cells,  with  a  con- 

tinual reproduction  in  the  same  manner,  is  observed  in 

animals,  in  the  formation  and  renovation  of  the  epi- 

dermis  and  its  appendages,  the  hairs  and  nails,  of  the 
YOLK  IN  THE  HUMAN  EGG.  epithelium  of  mucous  and  serous  membranes,  and  of 
i,  a  ripe  ovum;  2,  the  th  secreting  cens  Of  glandular  organs.  In  the  deepest 

yolk  divided  into  two;  3, 

yolk  divided  into   part  of  these  structures,  in  the  nutritive  liquid  con- 
g^antlv  exuding  from  the  capillarv  vessels,  homogeneous 

J 

granules  originate.  These,  which  constitute  nucleoli, 
successively  become  nuclei  and  organic  cells  in  the  following  manner. 
A  granule  or  nucleolus  first  appears  ;  and  upon  this  a  vesicular  wall  is 
developed,  inclosing  the  nucleolus.  In  the  liquid  contents  of  the  nucleus 
thus  formed,  granules  may  originate  ;  and  a  second  vesicular  wall  is  de- 
veloped, which  incloses  the  nucleus  and  thus  constitutes  an  organic  cell. 
The  contents  of  the  latter,  at  first  liquid,  become  more  or  less  granular. 
The  steps  of  the  process  just  related  are  represented  in  figure  9. 


the 

four;  4,  5,  the  yoikdivid 

ed  into  numerous  cells. 


INTRODUCTION. 


25 


FIG. 


FIG.  10. 


THREE  SECRETING 
CELLS  FROM  THE  SUB- 
MAXILLARY  SALIVART 
GLAND. 


PROCESS  OF  DEVELOPMENT  OF  AN  OR- 
GANIC CELL  FROM  A  GRANULE.  1,  a 
granule;  2,  a  vesicle  developed  upon 
the  granule:  the  two  constituting 
the  nucleus  and  contained  nucleolus; 
3,  the  same,  increased  in  size;  4,5, 
granules  developed  in  the  contained 
liquid  of  the  nucleus;  6,  the  cell  wall 
developed  on  the  nucleus ;  7,  8, 9,  suc- 
cessive increase  of  the  cell,  and  de- 
velopment of  granular  contents. 


Subsequent  to  the  development  of  organic  cells,  they  most  usually 
undergo  more  or  less  trans- 
formation in  the  produc- 
tion of  the  various  parts  of 
plants  and  animals.  In 
some  cases  the  modifica- 
tion is  so  slight  that  the 
original  form  remains  man- 
ifest, as  instanced,  by  the 
glandular  cells  generally,  in 
animals.  Thus  in  the  figure 
10,  representing  several  secreting  cells  of 
the  salivary  glands,  the  typical  organic  cell 
form  is  readily  recognized.  In  other  in- 
stances the  transformation  of  cells  is  so 
great  that  their  existence  would  not  be  sus- 
pected from  an  examination  alone  of  the 
structure  produced  from  them.  Thus  the 
fibrous  tissues,  which  consist  of  bundles  of 
the  finest  homogeneous  filaments,  are  the  result  of  the  subdivision  or 
splitting  of  organic  cells. 

Through  continued  reproduction,  aggregation,  and  transformation  of 
organic  cells,  the  various  textures  or  tissues  are  produced,  which  consti- 
tute the  proximate  physical  elements  of  the  various  organs  of  animals. 

ULTIMATE  CHEMICAL  ELEMENTS  OF  THE  HUMAN  BODY. 

1.  Oxygen.  5.  Chlorine.  9.  Sodium.  12.  Iron. 

2.  Hydrogen.  6.  Phosphorus.        10.  Potassium.  13.  Fluorine. 

3.  Carbon.  7.  Sulphur.  11.  Magnesium.  14.  Silicon. 

4.  Nitrogen.  8.  Calcium. 

Ox'ygen,  Hy'drogen,  and  Car'bon  are  found  in  all  the  tissues  and 
liquids  of  the  human  body.  Ni'trogen  is  likewise  found  in  all  except  fat; 

Chlo'rine  forms  with  hydrogen  the  chlorohydric  acid  of  the  gastric 
juice.  It  also  exists  in  combination  with  sodium  and  potassium  in  most 
of  the  tissues  and  liquids  of  the  body. 

Phos'phorus,  or  Sul'phur,  or  both  together,  exist  in  all  the  nitrogenized 
proximate  elements  of  the  body. 

Calcium,  oxydized  as  lime,  in  the  form  of  phosphate  of  lime,  and  in 
that  of  carbonate  of  lime,  enters  largely  into  the  composition  of  the 
bones  and  teeth,  and  is  also  found  in  small  quantities  in  some  other  parts 
of  the  body. 

So'dium  and  Potas'sium,  as  common  salt  or  chloride  of  sodium,  and  as 
chloride  of  potassium,  exist  in  most  of  the  tissues  and  liquids. 


26  INTRODUCTION. 

Magne'sium,  as  phosphate  of  magnesia,  is  found  in  the  bones,  and  in 
small  quantity  elsewhere. 

I'ron  exists  in  the  coloring  matter  of  the  blood  corpuscles.    Flu/orine, 
in  small  quantity,  as  fluoride  of  calcium,  is  found  in  bones.     Sil'icon,  as 
silica,  is  found  in  hairs. 
^ — 
PROXIMATE   CHEMICAL   ELEMENTS    OF   THE   HUMAN   BODY. 

GROUP    1. — NlTROGENIZED    ELEMENTS    PECULIARLY    ORGANIC. 

Fibrin.  Collagen.  Crystallin.  Pancreatin. 

Albumen.  Chondrigen.  Keratin.  Pepsin. 

Albuminose.  Elasticin.  Haematin.  Mucosin. 

Casein.  Neurin  ?  Ptyalin.  Melanin. 

Musculin.  Globulin. 

Many  of  the  elements  belonging  to  this  group  are  those  which  are 
least  known.  Thus  the  character  of  the  albumenoid  matter  (Neurin)  of 
the  nervous  system  has  not  been  ascertained,  nor  are  we  familiar  with  the 
important  proximate  constituents  of  the  liver,  kidneys,  salivary  glands, 
and  some  other  organs.  They  all  contain  oxygen,  hydrogen,  carbon,  and 
nitrogen ;  most  of  them  sulphur ;  and  many  of  them  phosphorus. 

Fi'brin  exists  in  the  blood  and  lymph  in  a  liquid  condition.  Its  most 
striking  peculiarity  is  its  spontaneous  coagulation  on  being  removed  from 
the  circulation. 

Albu/men  is  found  in  the  blood,  lymph,  and  fluids  of  the  serous  cavities 
in  a  liquid  condition.  It  coagulates  above  a  temperature  of  160°  Fahr.; 
also  through  the  agency  of  alcohol,  tannin,  the  mineral  acids,  and  the 
metallic  salts. 

Albu/minose  is  found  in  the  blood  and  chyle  in  a  liquid  condition.  It 
results  from  digestion,  in  the  alimentary  canal,  of  the  albuminous, 
fibrinous,  and  caseous  matters  of  food,  and  from  flesh ;  and  it  differs  from 
albumen  in  not  being  coagulable  by  heat. 

Ca'sein  is  the  most  important  constituent  of  milk,  in  which  it  exists  in 
the  fluid  condition.  It  coagulates  through  the  agency  of  acids,  but  not 
through  heat,  nor  spontaneously.  The  curdling  of  milk  is  due  to  the 
development  of  lactic  acid  from  the  sugar  of  milk. 

Mus'culin  is  the  soft  substance  of  flesh  or  muscles,  endowed  during  life 
with  the  power  of  contractility.  It  is  soluble  in  dilute  muriatic  acid ; 
boiling  in  water  renders  it  more  solid. 

Col'lagen  is  the  principal  constituent  of  the  so-called  bone  cartilage, 
ligaments,  tendons,  fibrous  membranes,  the  dermis,  and  the  areolar  tissue. 
By  boiling  in  water  it  is  resolved  into  gelatin  or  glue. 

Chon'drigen  is  the  basis  of  the  true  cartilages  and  of  the  cornea.    Long 


INTRODUCTION.  27 

boiling  resolves  it  into  chondrin,  which  differs  from  gelatin  in  being  pre- 
cipitated from  solution  by  acetic  acid  and  some  other  agents  not  acting 
on  the  latter. 

Elas'ticin  is  the  peculiar  solid  material  of  the  elastic  tissue.  It  is 
remarkably  insoluble  in  all  ordinary  menstrua. 

Neu/riii?  is  the  supposed  albumenoid  principle  of  the  nervous  system. 

GloVulin  forms  with  haematin  the  contents  of  the  red  blood  corpuscles. 

Crys'tallin  is  the  basis  of  the  crystalline  lens  of  the  eye.  It  is  coagu- 
lable  by  heat  and  by  alcohol ;  but  unlike  albumen,  is  precipitated  from 
solution' by  carbonic  acid. 

Ker'atin  is  the  principle  which  gives  the  horn-like  character  to  the 
epidermis,  nails,  and  hairs. 

Haem/atin  is  the  coloring  matter  of  the  red  blood  corpuscles. 

Pty'alin  is  found  in  the  salivary  glands  and  the  saliva. 

Pancrea'tin  exists  in  the  pancreas  and  its  secretion. 

Pep'sin  is  a  peculiar  principle  of  the  gastric  mucous  membrane  and 
gastric  juice. 

Mu/cosin  is  the  viscid  matter  of  mucus  and  the  mucous  epithelial  mem- 
branes. 

Mela'nin  is  the  dark  coloring  matter  of  the  choroid  tunic  of  the  eye 
and  of  the  skin  of  the  negro. 

GROUP    2. NON-NlTROGENIZED    ELEMENTS    PECULIARLY    ORGANIC. 

Olein.  Stearin.  Glycogen.  Lactin. 

Margarin.  Butyrin.  Glucose.  Inosit. 

All  of  these  have  for  their  ultimate  elements  oxygen,  hydrogen,  and 
carbon. 

O'lein,  Mar'garin,  and  Ste'arin,  mingled  together,  form  the  greater 
part  of  the  fats  of  the  human  body — margarin  being  the  most  abundant, 
and  stearin  the  least  so.  Olein  remains  liquid  even  below  the  freezing 
point ;  and  at  the  ordinary  temperature  of  the  body  it  retains  the  other 
fatty  matters  in  solution.  Margarin,  isolated,  becomes  a  crystalline 
solid,  below  118°  Fahr. ;  and  stearin  assumes  the  same  condition  below 
143°  Fahr.  With  alkaline  solutions,  the  three  fatty  substances  men- 
tioned undergo  decomposition,  evolving  oleic,  margaric,  and  stearic 
acids,  which  combine  with  the  alkaline  base,  as  in  the  ordinary  forma- 
tion of  soaps.  The  original  fat  base,  in  combination  with  water,  consti- 
tutes the  peculiar  sweet  liquid,  glycerin. 

Bu'tyrin,  in  combination  with  margarin  and  stearin,  forms  the  fatty 
part  of  cream  or  milk. 

Glyc'ogen  is  a  peculiar  substance  in  the  tissue  of  the  liver,  which 
undergoes  transformation  into  glucose. 


28  INTRODUCTION. 

Glu'cose,  commonly  known  as  grape  sugar,  is  found  in  the  liver  and 
the  blood  of  the  hepatic  vein,  and  in  less  quantity  in  other  blood. 

Lac'tin,  or  sugar  of  milk,  is  developed  in  the  mammary  gland,  and 
may  be  obtained  from  the  whey  of  milk,  in  a  crystalline  condition.  The 
souring  of  the  latter  liquid  arises  from  the  conversion  of  its  sugar  into 
lactic  acid. 

In'osit  is  a  saccharine  substance,  incapable  of  vinous  fermentation, 
found  in  the  muscular  structure  of  the  heart. 

GROUP  3. — ELEMENTS  NOT  PECULIARLY  ORGANIC. 

Water.  Phosphate  of  soda.  Carbonate  of  potassa. 

Chloride  of  sodium.  Phosphate  of  potassa.  Fluoride  of  calcium. 

Chloride  of  potassium.  Carbonate  of  lime.  Silica. 

Phosphate  of  lime.  Carbonate  of  soda.  Chloro-hydric  acid. 
Phosphate  of  magnesia. 

Water  is  one  of  the  most  important  proximate  principles  of  the  human 
and  all  other  organized  bodies.  It  is  the  vehicle  through  which  all  the 
other  proximate  elements,  with  perhaps  the  exception  of  a  portion  of  the 
fatty  matters,  are  rendered  capable  of  entering  into  the  composition  of 
the  body.  The  amount  of  water  in  the  different  parts  of  the  latter 
varies.  In  blood  it  is  equal  to  795  parts  in  the  thousand;  in  muscles 
about  750  parts  ;  and  in  bones  about  130  parts.  The  entire  body  con- 
sists of  more  than  two-thirds  its  weight  of  water. 

Chlo'ride  of  So'dium  and  of  Potas'sium,  and  more  especially  the 
former,  are  contained  in  solution  in  most  of  the  liquids  of  the  animal 
body. 

Phos'phate  of  Lime,  of  Magne'sia,  of  So'da,  and  of  Potas'sa  are  found 
in  solution  in  most  of  the  animal  liquids.  The  first  of  these  elements  is 
the  chief  material  to  which  the  hardness  of  the  bones  is  due. 

Car'bonate  of  Lime,  of  Soda,  and  of  Potassa  are  found  in  compara- 
tively small  quantity  in  the  human  body — the  first  chiefly  in  the  bones, 
the  latter  two  in  most  of  the  tissues. 

Flu'oride  of  Cal'cium  and  Sil'ica  also  exist,  in  small  quantity,  in  the 
body — the  former  in  bones,  the  latter  in  hairs. 

Chlo'ro-hy'dric  Acid  exists  in  the  gastric  juice. 

GROUP  4. — ELEMENTS  ARISING   FROM  THE  DISINTEGRATION  OF  THE  DIFFERENT 
PARTS  OF  THE  BODY,  FOR  THE  MOST  PART  EXPELLED  IN  THE  EXCRETIONS. 

Urea.  Taurocholate  of  soda.  Butyric  acid. 

Creatin.  Urates  of  soda,  potassa,  Formic  acid. 

Creatinin.  and  ammonia.  Acetic  acid. 

Biliverdin.  Cholesterine.  Oxalate  of  lime. 

Uroerythrin.  Lactic  acid.  Carbonic  acid. 


INTRODUCTION.  29 

TTre'a,  with  a  composition  of  carbon,  hydrogen,  oxygen,  and  nitrogen, 
is  the  most  important  constituent  of  the  urine — forming,  as  it  does,  about 
three-fourths  of  the  solid  matter  left  after  the  evaporation  of  the  water. 
It  crystallizes  in  the  form  of  four-sided  prisms.  In  small  quantity,  it  is 
found  in  the  blood  and  the  humors  of  the  eye,  and  is  considered  to  be 
derived  from  the  disintegration  of  the  nitrogenized  tissues. 

Cre'atin  and  Crea'tinin,  containing  the  same  ultimate  elements  as  the 
preceding,  are  two  crystallizable  principles  found  in  the  muscles,  from 
which  they  appear  to  be  given  up  to  the  blood,  to  be  excreted  in  the 
urine. 

Biliverd'in  and  TJroer/ythrin  are  coloring  matters — the  former  of  the 
bile,  the  latter  of  the  urine.  Both  have  the  four  ultimate  elements — 
carbon,  oxygen,  hydrogen,  nitrogen — entering  into  their  composition. 

Taurochol'ate  of  Soda,  consisting  of  taurocholic  acid,  containing  the 
same  elements  as  the  former  substances,  in  combination  with  soda,  is  an 
important  ingredient  of  the  bile. 

The  TJ'rates  of  Soda,  Potassa,  and  Ammonia,  consisting  of  uric  acid, 
with  the  same  elements  as  the  preceding,  in  combination  with  the  alka- 
line bases,  are  found  in  the  urine. 

Chol'esterine  is  a  crystallizable,  fatty  substance,  with  a  composition  of 
carbon,  hydrogen,  and  oxygen,  but  is  unsaponifiable.  It  is  found  in  the 
juices  of  the  nerve-centres  and  the  blood,  and  is  excreted  in  the  bile. 

Lac'tie  Acid,  with  a  composition  of  carbon,  hydrogen,  and  oxygen,  is 
found  in  the  muscles  and  gastric  juice. 

Butyr'ic,  Ace'tic,  and  Form'ic  Acids,  containing  the  ultimate  elements, 
carbon,  hydrogen,  oxygen,  are  obtained  from  the  juice  of  the  muscles, 
and  are  excreted  in  the  sweat. 

Ox'alate  of  Lime  is  found  in  small  quantity  in  the  urine. 

Carbon/ic  Acid  is  found  in  the  blood  and  other  liquids  of  the  body. 

ULTIMATE  PHYSICAL  ELEMENTS  OF  THE  HUMAN  BODY. 

1.  Homogeneous  liquid  and  its  transitions  to  a  solid  condition. 

2.  Homogeneous  granules. 

3.  Homogeneous  filaments. 

4.  Homogeneous  membrane. 

Homoge'neous  liquid  is  observed  in  the  fluids  of  the  body,  varying  in 
consistence  in  different  cases,  as  instanced  by  the  liquor  of  the  blood  and 
lymph,  serum,  mucus,  and  the  juices  of  the  tissues. 

Homoge'neous  gran'ules  form  an  important  constituent  of  many  tis- 
sues, as  in  the  contents  of  the  secreting  cells  of  glands,  and  epithelial 
cells,  and  in  the  ash-colored  portion  of  the  nervous  system. 


30  INTRODUCTION. 

Homoge'neous  fil'aments  form  the  principal  constituent  of  the  true 
fibrous  tissues,  and  the  vibrating  appendages  of  ciliated  epithelial  cells. 
Hbmoge'neous  mem/brane  constitutes  the  basement  membrane  of  the 
serous  and  mucous  membranes,  and  glands.  It  also  forms  the  wall  of 
capillary  vessels,  the  sheath  of  muscular  and  nerve  fibres,  and  the  parietes 
of  organic  cells. 

The  human  body  has  its  origin  in  the  ovary  of  the  mother,  and  starts 
into  definite  existence  as  a  homogeneous  granule,  which,  in  course  of 
development,  becomes  an  organic  cell.  This  constitutes  the  primitive 
ovum  ;  which,  after  escaping  from  the  ovary,  traverses  the  oviduct,  to  be 
received  into  the  uterus.  Being  subjected  to  the  influence  of  the  sper- 
matic liquid  of  the  male,  its  contents  undergo  a  series  of  segmentations, 
resulting  in  the  production  of  a  mass  of  organic  cells,  inclosed  within  the 
parent  cell.  Continually  imbibing  nourishment  from  the  exterior,  the 
ovum  gradually  increases  in  size,  and  step  by  step  the  embryo  is  evolved, 
the  development  of  all  its  parts  being  preceded  by  the  production  of 
organic  cells,  through  division  of  previously  existing  cells.  It  thus  fol- 
lows, that  all  the  organs  and  tissues  of  the  human  body — and  this  will 
equally  well  apply  to  all  organized  bodies,  except  the  simplest  forms 
before  mentioned — are  derived  from  organic  cells. 

The  degree  of  transformation  of  organic  cells,  in  the  production  of  the 
fully-developed  tissues  of  the  human  body,  varies  from  a  condition  of  no 
perceptible  change  in  the  typical  form,  through  a  gradation  of  condi- 
tions, to  such  as  lose  all  trace  of  the  original  cell-form. 

In  the  lymph  corpuscles  (figure  11)  and  the  simple  ganglionary  cells, 
we  have  an  instance  of  organic  cells  retaining,  throughout 
their  existence,  the  original  form. 

In  the  medullary  cells  of  the  spongy  part  of  bones,  the 
adipose  cells,  and  the  secreting  cells  of  many  glands,  the 
A  LYMPH  COR-    original  cell-form  is  simply  modified,  by  mutual  pressure, 

so  as  to  assume  a  polyhedral  appearance. 

In  the  epithelium  of  serous  membranes,  the  original  cell-form  is  modi- 
fied by  its  not  only  assuming  the  polyhedral  outline,  but  from  the  breadth 
transcending   the   thickness,    as   represented   in 
figure  12. 

In  the  epidermis,  and  the  epithelium  of,  the 
mouth,  the  organic  cells,  which  continually  orig- 
inate in  the  deep  parts  of  these  structures,  as 
EPITHELIAL  CELLS  OF  A  SEROUS     they  rise  toward  the  free  surface,  assume  the  form 
MKMBRANE    «  viewed  on  the     of  broad  gcal      ag  represented  by  the  diagrams 

broad  surface;  o,  viewed  in  the  * 

thickness.  m  figure  13. 


INTRODUCTION. 


31 


In  the  epithelium  of  the  stomach  and  intestines,  the  organic  cells, 
which  originate  as  in  the  former  instance,  assume  the  form  of  prismatic 
columns,  as  represented  in  figure  14,  a. 


FIG.  13. 


MODE  OF  DEVELOP- 
MENT, FROM  BELOW  UP- 
WARD, OF  THE  COLUM- 
NAR EPITHELIAL  CELLS. 

a,  epithelial  cell  of 
the  stomach  and  in- 
testines; 6,  epithelial 
cell  of  the  pulmonary 
mucous  membrane. 


In  the  epithelium  of  the  air- 
passages,  the  organic  cells  un- 
dergo the  same  changes  as  in 
the  case  just  mentioned ;  but,  in 
addition,  have  developed,  upon 

their  free  extremities,  vibrating  appendages,   as  represented   in  figure 
14,6. 

In  the  formation  of  the  unstriated  muscular  fibres,  the  organic  cells 
become  elongated  into  fusiform  bands,  as  represented  in  figure  15,  a-c. 


EXHIBITS  THE  PROGRESSIVE  DEVELOPMENT,  FROM 
BELOW  UPWARD,  OF  THE  SCALES  OF  THE  EPIDERMIS, 
or  the  scale-like  epithelium  of  the  mouth,  a, 
the  thickness;  b,  the  breadth. 


FIG.  17. 


FIG.  15. 


FIG.  16. 


MODE   OF   DEVELOPMENT   OF   UNSTRIATED 

MUSCULAR  FIBRE,    a,  b,  c,  cells  success- 
ively  elongating  into  a  fusiform  fibre. 


NERVE  CELL,  from 
the  ash-colored  mat- 
ter of  the  cerebrum. 


MODE    OF    DEVELOPMENT    OF    CAPILLARY 

VESSELS  FROM  CELLS,  a,  cell  with  four 
prolongations;  b,  vessels  formed  from 
the  conjunction  of  the  prolongations  of 
cells.  The  nuclei  remain  adhering  to 
the  structureless  walls  of  the  vessels. 


The  caudated  nerve  cells  are  produced  by  the  organic  cells  sending  off 
a  number  of  processes,  as  represented  in  figure  16. 

In  the  formation  of  capillary  vessels,  organic  cells  protrude  append- 
ages, which  unite  with  one  another,  and  thus  form  an  intercommunicating 
system  of  tubes,  as  represented  by  the  diagram,  figure  IT. 

In  the  development  of  the  seriated  muscular  fibres,  cells  arrange  them- 
selves in  rows,  and  become  united  into  continuous  columns,  as  repre- 
sented in  figure  18,  a-d. 


32 


INTRODUCTION. 


FIG.  19. 


In  the  formation  of  the  fibrous  tissues,  constituting  the  ligaments,  ten- 
dons, the  dermis,  and  areolar  tissue,^ 
organic  cells  split  up  into  bundles 
of  fine  filaments,  as  represented  in 
figure  19,  a-/ 

FIG.  18. 


A 

DEVELOPMENT  OF  STRIATED  MUSCULAR  FIBRE,  FROM 
CELLS,  a,  simple  cell ;  6,  a  pair  of  cells  fused  to- 
gether ;  c,  three  cells  fused,  and  their  contents  as- 
suming the  striated  character ;  d,  a  muscular  fibre, 
exhibiting  its  original  composition  of  cells. 


DEVELOPMENT  OF  FIBROUS  TISSUE,  a,  simple  cell; 
6,  the  same  elongated ;  c,  d,  e,  the  same  becoming 
successively  more  and  more  divided ;  /,  the  same 
split  into  a  bundle  of  filaments,  among  which  the 
nucleus  remains. 


THE  PROXIMATE  PHYSICAL  ELEMENTS  OR  TISSUES  OF  THE 

HUMAN  BODY. 


1.  Tissue  of  free  cells  floating  in  a 

liquid. 

Blood  corpuscles,  with  the  contain- 
ing liquor. 

Lymph  corpuscles,  with  the  con- 
taining liquor. 

2.  Tissue  of  cells  arranged  in  layers 

usually  on  free  surfaces. 
Epidermis,  nails,  and  cuticle  of  hairs. 
Epithelium  of  serous  and  mucous 

membranes. 
Glandular  cells. 
Pigment  cells. 

Nerve  cells  of  retina  and  labyrinth. 
Enamel. 

3.  Tissue  of  cells  aggregated  in 

masses. 
Adipose  tissue. 

Medullary  tissue  of  spongy  bones. 
Medulla  of  hairs. 
Ash-colored  nerve  tissue. 
Closed  gland  tissue. 


4.  Tissue  of  cells  imbedded  in  a 

solid  non-cellular  substance. 

Cartilage. 
Bone. 

5.  Tissue  of  cells  forming  fusiform 

bands. 

Unstriated  muscular  fibres. 
Cortical  portion  of  hairs. 

6.  Tissue  of  cells  metamorphosed 

into  tubes  with  liquid,  semi- 
liquid,  or  solid  contents. 

Capillaries. 

Nerve  fibres. 

Striated  muscular  fibres. 

Crystalline  fibres. 

Dentine. 

7.  Tissue  of  cells  completely  meta- 

morphosed into  filaments. 
Fibrous  tissue. 
Elastic  tissue. 


CHAPTER  II. 

THE     SKELETON. 

THE  Skeleton  is  the  frame-work  of  the  body,  and  is  composed  of  an 
articulated  assemblage  of  hard  organs,  the  bones.  It  serves  to  preserve  the 
shape  of  the  body ;  forms  cases  for  the  protection  of  the  most  important 
viscera ;  and  gives  attachment  to  muscles  and  forms  levers  of  movement. 
For  convenience  of  description  and  study  it  is  usually  considered  in 
parts  corresponding  with  the  ordinary  divisions  of  the  body ;  as  the  head, 
trunk,  and  the  upper  and  lower  extremities. 

The  number  of  distinct  pieces  or  bones  composing  the  skeleton 
varies  at  different  periods  of  life.  Some  remain  distinct  from  the 
first  moment  of  their  development,  such  generally  being  of  the  simplest 
form,  as  the  bones  of  the  carpus,  the  parietal  bone,  and  the  patella. 
Others,  which  are  viewed  as  single  bones  in  the  adult,  not  only 
consist  of  several  pieces  in  the  beginning,  but  in  the  progress  of  develop- 
ment have  other  pieces  'successively  added,  as  in  the  case  of  the  vertebrae 
and  the  thigh-bones.  Again,  bones  considered  as  distinct  pieces  when 
the  body  has  arrived  at  maturity,  at  a  later  period  may  become  united 
with  those  which  are  contiguous,  as  in  the  co-ossification  of  the  cranial 

bones. 

The  number  of  bones  to  which  we  usually  refer  in  the  description  of 

the  skeleton  is  as  follows  : — 

For  the  head ;  including  the  hyoid  bone  and  excluding  the  teeth  and  the 
small  bones  of  the  ear 23 

For  the  trunk;  counting  the  coccyx  as  four,  the  sternum  as  three,  and 
including  the  hip-bones 59 

For  the  upper  extremities;  including  the  sesamoid  bones,  thirty-four  to 
each  extremity .68 

For  the  lower  extremities  ;  thirty-two  to  each     ......     64 

214 

The  bones  are  connected  together,  in  the  construction  of  the  skeleton, 
by  various  means,  viz. :  by  cartilages,  fibro-cartilages,  and  ligaments. 

3  (33) 


34  THE   SKELETON. 

The  connections  are  named  the  joints  or  articulations,  and  the  parts  of 
the  bones  involved  are  called  the  artic'ular  extremities,  borders,  or 
surfaces,  as  the  case  may  be. 

The  bones  of  the  two  sides  of  the  skeleton  are  either  in  pairs,  as  the 
ribs  and  those  of  the  extremities,  or  they  are  single  and  symmetrical ; 
that  is,  they  consist  of  two  similar  halves,  as  the  vertebra.  They  vary 
much  in  relative  proportion  and  form,  and  in  these  respects  are  divisible 
into  four  classes  :  the  long  bones,  such  as  the  principal  ones  of  the  limbs ; 
the  tabular  bones,1  as  those  of  the  vault  of  the  cranium  ;  the  irregular 
bones,  as  the  vertebras ;  and  the  short  bones,2  as  those  of  the  wrist. 

The  long  bones  have  a  more  or  less  cylindroid  or  prismoid  shaft  or 
body ;  which  latter  term  is  also  applied  to  the  massive  part  of  irregular 
bones.  The  extremities  of  a  long  bone  are  dilated,  and  support  smooth 
articular  surfaces.  From  their  respective  position  in  relation  with  the 
vertebral  column,  that  which  is  nearer  to  the  latter  is  called  the  proximal 
extremity,  and  the  more  distant,  the  distal  extremity.  If  an  extremity 
forms  a  single  rounded  prominence  it  is  called  a  head ;  but  if  there  are 
such  a  pair  of  prominences,  they  are  called  con'dyles ;  though  this  name 
is  also  applied  to  the  single  articular  eminences  of  the  occipital  bone 
and  the  lower  jaw,  and  even  to  the  tubercles  on  each  side  of  the  distal  end 
of  the  humerus.  The  narrow  or  constricted  portion  intervening  between 
a  head,  condyles,  or  other  articular  eminence,  and  the  principal  part  of 
a  bone,  is  called  the  neck. 

Any  elevation  or  prominence  may  be  termed  a  proc'ess.3  If  this  be 
narrow  and  tapering  it  is  usually  named  a  spi'nous  process,  though  the 
term  is  frequently  applied  to  an  obtuse  prominence,  which  is  also  called 
a  tu'bercle,  or  a  tuberos'ity.  An  eminence  supporting  an  articular 
surface  is  termed  an  artic'ular  proc'ess  An  elevation  extending  some 
distance  along  the  surface  of  a  bone,  or  a  prominent  border,  is  named  a 
line,  ridge,  or  crest. 

An  aperture  in  a  bone  or  between  several  bones  is  called  a  fora'men, 
(plural :  fora'mina,)  and  if  this  is  prolonged  for  some  distance  it  becomes 
a  canal,  or  mea'tus.  A  broad  shallow  depression  is  termed  a  fos'sa, 
(plural :  fos'sae,)  and  a  cavity  with  a  small  external  communication  is  a 
si'nus. 

Bones  in  the  fresh  condition  are  white,  with  a  faintly  bluish  translu- 
cency,  tinged  with  pink  from  the  blood  with  which  they  are  supplied  ;  and 
they  are  more  pink  or  red  the  younger  they  are,  from  their  greater  degree 
of  vascularity.  When  cleansed  of  their  softer  attachments  by  boiling  or 
maceration,  and  dried,  they  lose  in  weight  and  become  dull  yellowish 

1  Synonym  :  Broad  bones.  2  Thick,  or  massive  bones.  3  Apophysis. 


THE  SKELETON.  35 

white ;  and  if  exposed  to  the  combined  influence  of  the  air,  moisture, 
and  light,  they  acquire  a  more  or  less  chalk-white  appearance.  They  are 
hard,  tough,  and  moderately  elastic,  which  qualities  vary  with  their  age  ; 
being  tougher  and  more  elastic  the  younger  they  are,  and  harder  and 
more  brittle  the  older  they  are. 

Human  bones  are  nearly  twice  as  heavy  as  water,  their  specific  gravity 
being  T92.  Their  chemical  composition  at  mature  age,  according  to 
recent  analyses,  is  as  follows  : — 

Bone-cartilage  and  blood-vessels 32'56 

Phosphate  of  lime 53-61 

Carbonate  of  lime 9*41 

Phosphate  of  magnesia,  fluoride  of  calcium,  chloride  of  sodium,  soda, 

oxides  of  iron  and  manganese,  traces  of  silex,  and  loss       .         .         .  4-42 

100-00 

Prom  this  table  it  will  be  perceived  that  about  one-third  of  peculiar 
animal  matters  and  two-thirds  of  ordinary  mineral  matters  enter  into 
the  composition  of  bones.  The  relative  proportion  of  the  different 
matters,  however,  varies  with  age.  The  skeleton  commences  in  the  em- 
bryo in  a  cartilaginous  condition  ;  the  mineral  matters  are  subsequently 
added  in  the  course  of  development,  and  they  increase  in  relative  quan- 
tity with  the  advance  of  age.  In  the  infant  the  different  matters  exist 
in  the  proportion  of  about  half  and  half;  from  old  bones  as  much  as 
seven-eighths  of  mineral  matters  have  been  obtained. 

To  the  peculiar  animal  matters,  bones  owe  their  tenacity  and  elasticity; 
to  the  mineral  matters,  their  hardness  and  rigidity.  These  qualities  vary 
in  degree  with  age,  in  accordance  with  the  difference  in  relative  propor- 
tion of  the  two  kinds  of  matters.  Hence  the  great  predominance  of 
mineral  matters  in  the  bones  of  old  persons  is  one  of  the  reasons  why 
they  are  so  much  more  liable  to  fracture  than  in  young  persons. 

When  bones  are  burned,  from  the  charring  of  their  cartilage  they 
become  black  and  brittle  ;  in  this  condition  constituting  the  bone-black 
of  the  arts.  If  the  bone  cartilage  is  entirely  consumed,  the  mineral 
matters  remain,  still  preserving  the  original  form  of  the  bones,  which  have 
now  become  pure  white  and  exceedingly  friable.  From  such  calcined 
bones  the  phosphorus  of  commerce  is  obtained. 

When  bones  are  steeped  in  diluted  hydrochloric  acid,  most  of  the 
mineral  matters  are  dissolved  out,  and  the  cartilage  is  left  as  a  tough, 
flexible,  gristle-like  substance,  retaining  the  original  form  of  the  bones. 
This  bone  cartilage,  by  boiling,  is  reduced  into  the  condition  of  gelatin. 
When  bones  are  boiled  under  high  pressure,  the  gelatin  is  extracted; 
and  it  has  been  obtained  in  this  manner  for  the  making  of  jellies  and 


36  THE  SKELETON. 

soups.  Dogs,  wolves,  cats,  and  other  carnivorous  animals  eat  bones, 
from  which  the  gastro-intestinal  liquids  thoroughly  extract  the  gelatin, 
while  the  mineral  matters  are  expelled  as  excrement.1 

The  surface  of  bones,  closely  examined,  exhibits  a  more  or  less  distinctly 
fibrous  appearance  ;  and  it  is  perforated  with  numerous  minute  foramina 
for  the  transmission  of  blood-vessels.  The  articular  surfaces  present  an 
even  or  close  structure,  and  in  the  recent  condition  are  covered  with 
plates  of  cartilage.  The  extremities  of  long  bones  and  the  bodies  of 
irregular  bones  present  numerous  comparatively  large  foramina,  which 
transmit  blood-vessels,  chiefly  veins. 

The  bones  are  composed  of  an  exterior  more  compact  layer,  and  an 
interior  looser  arrangement  of  the  same  structure  ;  the  two  being  distin- 
guished as  the  compact  and  spongy  substances. 

In  the  long  bones  the  compact  substance  forms  the  wall  of  the  hollow 
shaft,  and  gradually  diminishes  to  a  thin  layer  investing  the  extremities. 
The  spongy  substance  forms  the  great  bulk  of  the  latter,  and  gradually 
diminishes  in  the  interior  toward  the  middle  of  the  shaft. 

The  large  hollow  occupying  the  interior  of  the  shaft  of  the  long  bones 
of  the  limbs  is  the  med'ullary  cavity,  It  is  filled  with  a  soft,  yellow  fat, 
the  marrow  or  medulla. 

At  the  sides,  and  especially  at  the  ends,  of  the  medullary  cavity, 
a  portion  of  spongy  substance  is  found,  consisting  of  a  delicate  network 
of  fibres,2  which  appears  to  be  serviceable  in  sustaining  the  position  of 
the  mass  of  marrow  and  supporting  the  blood-vessels  that  supply  the 
latter. 

The  medullary  cavity  communicates  with  the  exterior  by  means  of  one 
or  more  long,  oblique  canals,  which  pierce  its  wall  from  near  the  middle 
of  the  shaft,  and  accommodate  the  principal  medullary  nutritious  blood- 
vessels. 

The  areolae  or  interspaces  of  the  spongy  substance  are  occupied  by  a 
red,  semi-solid  marrow,  resembling  in  chemical  composition  the  extract 
of  beef. 

In  the  foetus  the  medullary  cavity  does  not  exist,  but  is  gradually 
formed  through  a  solution  or  removal  of  spongy  substance  occupying 
the  axis  of  the  bone.  It  gradually  increases  in  size  with  the  advance  of 
age  ;  and  in  its  progress  successive  layers  of  compact  substance  become 
spongy  substance,  which  in  turn  becomes  looser  in  structure,  and  is 
finally  removed. 


1  This  fact  it  appears  is  not  sufficiently  estimated  in  the  question  whether  gelatin 
is  nutritious  or  not. 

2  Cancellated  or  reticulated  substance. 


THE  SKELETON. 


37 


FIG.  20. 


The  broad  bones  are  composed  of  an  exterior  moderately  thick  layer 
of  compact  substance,  with  an  intervening  layer  of  spongy  substance.1 
The  bodies  of  irregular  bones,  and  the  short  bones,  are  composed  of  a 
mass  of  spongy  substance  enveloped  with  a  comparatively  thin  layer  of 
compact  substance. 

The  spongy  substance  of  bones  generally  is  pervaded  by  irregular 
canals  for  the  accommodation  of  veins.  They  are  especially  conspicuous 
in  the  bones  of  the  cranial  vault.2 

All  the  foramina  of  the  surfaces  of  bones,  canals,  and  areola3  of  the 
spongy  substance  and  medullary  cavities,  where  they  exist,  freely  inter- 
communicate ;  so  that  if  mercury  be  poured  in  at  one  extremity  of  a  long 
bone  deprived  of  its  marrow,  it  may  be  observed  to  stream  from  the 
foramina  at  the  other  extremity. 

The  compact  substance  is  relatively  thickest  or  most  abundant  where 
bones  are  most  slender  or  thin,  in  positions  in  which  they  are  required 
to  give  the  strongest  support  or  offer  the  greatest  degree  of  resistance  to 
muscular  action,  and  in  parts  of  the  body  most  exposed  to  injury  from 
external  violence. 

The  introduction  of  the  spongy 
substance  into  bones  increases  their 
bulk  to  a  convenient  size  without 
a  proportionate  increase  in  weight ; 
and  the  extension  of  surface  pro- 
duced by  its  presence  where  they 
articulate,  very  much  reduces  the 
liability  of  their  displacement  or 
dislocation.  Further,  the  substitu- 
tion of  the  spongy  for  the  compact 
substance,  very  much  reduces  the 
force  of  concussion  from  blows  or 
falls.  In  animals  whose  recumbent 
position  renders  them  little  liable 
to  the  latter  accidents,  the  bones 
contain  a  comparatively  small  quan- 
tity of  spongy  substance,  as  in  the 
alligator. 

At  first  view  it  might  be  supposed 
that  the  spongy  substance  consisted 
of  small  plates  and  fibres  of  bone  arranged  without  order,  and  even 


LONGITUDINAL  SECTION  OF  THE  PROXIMAL  EXTREM- 
ITY OF  THE  FEMUR,  exhibiting  the  arrangement  of 
the  spongy  substance.  1,  2,  positions  in  which  the 
compact  substance  appears  to  resolve  itself  into  a 
series  of  arches. 


1  Diploe  ;  diploic  structure. 

2  Where  they  are  named  the  diploic  sinuses. 


THE  SKELETON. 


FIG.  21. 


thrown  into  the  utmost  confusion.  This  is,  however,  not  the  case,  as  it 
always  has  the  same  general  arrangement  in  the  corresponding  bones ; 
and  this  arrangement  is  of  such  a  character  that  it  contributes  to  give 
strength.  Thus,  if  a  longitudinal  section  be  made  of  the  proximal 
extremity  of  the  femur,  (figure  20,)  it  will  be  observed  that,  as  the 
compact  substance  forming  the  walls  of  the  shaft  thins  out,  it  appears 
to  do  so  by  sending  off  on  each  side  successive  arching  plates,  which,  by 
crossing,  not  only  mutually  sustain  one  another,  but  also  contribute  to 
the  support  of  the  surfaces  with  which  they  are  connected. 

In  a  transverse  section  of  the  condyles  of  the  same  bone,  (figure  21,) 

it  may  be  noticed  that  the  exterior  is 
formed  of  a  layer  of  compact  sub- 
stance, very  little  thicker  than  the 
numerous  plates  of  the  spongy  sub- 
stance, which  act  as  so  many  beams 
extending  between  the  anterior  and 
posterior  surfaces.  These  antero- 
posterior  plates  are  supported,  at 
short  distances,  by  cross-pieces ; 
and  the  whole  is  further  strength- 
ened by  numerous  plates,  radiating 
from  a  compact  nucleus,  situated  at 
the  bottom  of  the  inter-condyloid 
notch. 

In  a  vertical  section,  antero-posteriorly,  of  the  calcaneum,  (figure  22,) 

the  bone  will  be  seen  to  be  com- 
posed of  a  thin  exterior  layer  of 
compact  substance,  with  thickened 
nuclei  at  the  position  of  support  of 
the  astragalus,  and  at  its  base. 
From  the  upper  nucleus,  plates  of 
the  spongy  substance  radiate  in  all 
directions ;  and  these  are  crossed 
by  arching  plates,  proceeding  from 
the  nucleus  at  the  base  of  the  bone. 
A  vertical  section,  antero-poste- 
riorly, of  a  vertebra,  exhibits  the 
body  composed  of  an  exterior  thin 
layer  of  compact  substance,  with  the  spongy  substance  composed  of  ver- 
tical and  transverse  columns,  mutually  supporting  one  another  and  the 
surfaces  of  the  bone.  The  spinous  process,  which  performs  the  part  of  a 


HORIZONTAL  SECTION  OF  THE  CONDYLES  OF  THE  FE- 
MUR, exhibiting  the  arrangement  of  the  spongy 
substance. 


FIG.  22. 


VERTICAL  SECTION,  ANTERO-POSTERIORLY,  OF  THE 
CALCANEUM,  exhibiting  the  arrangement  of  the 
spongy  substance.  1,  nucleus  of  compact  sub- 
stance below  the  articulation  of  the  astragalus, 
from  whence  start  off  numerous  radiating  fibres; 
2,  nucleus  of  compact  substance,  sending  off  nu- 
merous arching  fibres. 


THE  SKELETON.  39 

lever  for  muscular  action,  is  composed  of  a  thick  layer  of  compact  sub- 
stance, with  a  very  small  proportion  of  strong  spongy  substance. 

The  section  of  one  of  the  tabular  bones  of  the  cranial  vault  presents 
two  moderately  thick  plates  of  compact  substance,  mutually  supported 
by  intervening  columns  of  spongy  substance,  with  lateral  offsets. 

The  examples  thus  given  are  amply  sufficient  to  prove  that  the  spongy 
substance  possesses  an  admirable  mechanical  arrangement,  adapted  to 
contribute  strength  to  the  bones  of  which  it  forms  a  part. 

The  hollow,  columnar  condition  of  the  shaft  of  the  long  bones  of  the 
limbs  gives  several  advantages  over  a  solid  rod  containing  the  same 
amount  of  material.  Besides  the  increase  of  surface  for  muscular  attach- 
ment, an  increase  of  strength  is  obtained ;  as  it  is  well  known,  in  the 
mechanic  arts,  that  a  hollow  column  is  much  stronger,  or  capable  of  sus- 
taining a  much  greater  weight,  than  a  solid  column  containing  the  same 
amount  of  material ;  and  hence  it  is  that  metallic  columns  of  support  are 
made  hollow.  Another  familiar  application  of  this  principle  in  nature  is 
exhibited  in  the  construction  of  the  culm  or  stem  of  most  grasses — so 
admirably  adapted  to  the  support  of  their  treasures  of  grain,  while  they 
are  yet  so  light  as  to  bend  beneath  the  gentlest  breeze. 

The  exterior  of  bones,  except  at  the  articular  surfaces,  is  everywhere 
invested  with  a  fibrous  membrane,  called  perios'teum,  which  serves  as  a 
nidus  for  the  blood-vessels  entering  the  numerous  foramina  of  bones,  while 
it  affords  a  medium  of  attachment  for  muscles  and  other  organs.  From 
young  bones,  this  membrane  may  be  readily  separated  by  dissection ;  but 
in  the  progress  of  age  it  becomes  most  intimately  blended  with  the  sur- 
face of  the  bones.  The  delicate  vascular  network,  strengthened  by  a  few 
filaments  of  fibrous  tissue,  lining  the  areolaB  of  the  spongy  substance 
and  the  medullary  cavity,  is  called  endos'teum. 

The  marrow,  or  medulla,  is  of  two  kinds — that  which  fills  the  hollow 
shaft  or  medullary  cavity  of  the  long  bones  of  the  limbs,  and  that  which 
fills  the  areolaB  or  interspaces  of  the  spongy  substance  generally.  The 
former  is  a  soft,  yellow  fat,  consisting  of  delicate  adipose  cells ;  the  latter 
is  a  red,  pulpy  matter,  which,  in  chemical  composition,  resembles  the  ex- 
tract obtained  in  boiling  meat.  It  also  contains  fat,  which  increases  in 
quantity  with  the  advance  of  age.  Examined  with  the  microscope,  it  is 
found  to  consist  of  nucleated  cells. 

The  bones  are  pervaded  by  blood-vessels,  which  communicate  with  those 
of  the  periosteum  and  endosteum.  The  general  course  of  these  nutritious 
vessels  corresponds  with  the  fibrous  arrangement  more  or  less  distinctly 
observable  on  the  surface  of  bones ;  and  hence  it  is,  for  the  most  part, 
longitudinal  in  the  shaft  of  long  bones. 


40 


THE  SKELETON. 


The  osseous  tissue  is  arranged  in  concentric  layers  around  the  course 

of  the  vascular  canals1  of  the  bones ; 
so  that  if  a  transverse  section  of  the 
shaft 


of  a  long  bone  be  made 
of  sufficient  thinness  to  transmit 
light,  and  be  viewed  with  the  micro- 
scope, it  will  be  observed  to  be 
perforated  with  circular  and  oval 
orifices  of  the  divided  vascular  ca- 
nals, surrounded  by  rings  of  osseous 
tissue,  as  represented  in  figure  23. 
In  a  longitudinal  section  the  vas- 
cular canals  are  seen  generally  pur- 
suing the  same  direction,  inclosed 
on  each  side  with  plates  of  osseous 
tissue. 

In  very  many  instances,  in  the 
transverse  section  of  a  bone,  it  may 
be  observed  that  the  outer  lamina 
of  a  series  of  ossific  plates  sur- 
rounding the  vascular  canals  are 
more  or  less  interrupted,  in  their 
course,  by  the  encroachment  of  con- 
tiguous laminae  belonging  to  neigh- 
boring canals,  apparently  the  result 
of  absorption,  from  pressure,  more 
or  less  mutual  and  outward,  from 
the  vascular  canals. 

In  young  and  growing  bones,  in 
accordance  with  their  greater  de- 
gree of  vascularity,  the  vascular 

canals  are  more  numerous  than  in  older  ones.     The  surrounding  osseous 

lamina?  are,  however,  less  numerous;   and  these  appear  to  increase  in 

number  with  the  development  and  growth  of  bones. 

At  the  surface  of  bones,  in  transverse  sections,  parallel  layers  of  osseous 

tissue,  more  or  less  interrupted,  are  observable,  which  are  those  last 

deposited  by,  or  formed  from,  the  periosteum. 

The  fibres  and  plates  of  the  spongy  substance  are  composed  of  lamina) 

of  osseous  tissue,  which  appear  to  be  the  remains  of  concentric  series  of 

laminaB  that  once  surrounded  vascular  canals  but  now  form  walls  to  the 

areolae  containing  marrow. 


TRANSVERSE  SECTION  OF  THE  SHAFT  OF  A  PHA- 
LANX, moderately  magnified.  The  upper  part  of 
the  figure  corresponds  with  the  exterior  surface 
of  the  bone;  the  lower  part  with  the  interior  spongy 
substance. 


1  Canals  of  Havers;  Haversian  canals. 


THE  SKELETON. 


41 


Fio.  24. 


In  and  between  the  laminae  of  osseous  tissue,  as  seen  in  figure  24,  there 
exist  numerous  minute 
lenticular  excavations, 
called  lacu/nae,1  from 
which  diverge  a  multi- 
tude of  exceedingly  fine 
branching  tubes  or  can- 
alic'uli,  perforating  the 
osseous  laminas,  and  free- 
ly communicating  with 
one  another  and  with 
the  vascular  canals.  By 
means  of  this  arrange- 
ment a  free  intercommu- 
nication is  established 
for  the  conveyance  of nu- 
tritive matter  through- 
out the  osseous  structure. 

The  lacunaB  and  canal- 
iculi,  when  viewed  in  a 
section  of  bone  by  trans- 
mitted light,  appear  as 

black  fusiform  Spots  with       TRANSVERSE  SECTION  OF  BONE  FROM   THE  SHAFT  OF   THE  FEMUR, 

-. .  highly  magnified.  The  large  circular  orifices  are  transverse  sections 

numerous  minute  divei'g-  of  the  vascular  canalgj  8urrounded  by  concentric  layers  of  osseous 

illg  black  lines.       By   re-  substance.     Between  the  latter  are  seen  the  lenticular  excavations 

fleeted  light  they  appear  °F  laCUnS5  int~-icatinS  by  means  of  canaliculi. 

opaque  white  upon  a  more  translucent  ossific  matrix. 

The  osseous  laminae,  when  isolated  and  highly  magnified,  exhibit  a 


FIG.  25. 


FIG.  26. 


AN  OSSEOUS  LACUNA,  exhib- 
iting its  numerous  diverging 
canaliculi;  highly  magnified. 


faintly  longitudinal  retic- 
ular  arrangement,  as  if 
they  were  composed  of  an 
intertexture  of  filaments; 
and  indeed  when  the  car- 
tilage of  bone  is  mace- 
rated in  diluted  muriatic 
acid,  it  is  resolved  into  a 
mass  of  the  finest  cotton- 
like  filaments. 

In  positions  where  bones 
or  parts  of  them  are  very 
thin,  as  in  the  lachrymal  bYe~buu>ne  oniyln  focus. 


THIN      PLATE      FROM     THE 

ETHMOID  BONE,  without  pre- 
paration ;  highly  magnified. 
Two  planes  of  lacuna?  visi- 


Corpuscles  of  Purkinje. 


42 


THE  SKELETON. 


bone,  the  edge  of  the  squamous  portion  of  the  temporal  bone,  and  the 
thin  plates  of  the  ethmoidal  sinuses,  (figure  26,)  they  are  composed  of 
parallel  osseous  lamina,  with  intervening  lacunae,  which  communicate  by 
means  of  their  canaliculi  with  the  exterior  surfaces  covered  with  perios- 
teum, from  the  vessels  of  which  they  imbibe  nutritive  matter. 

DEVELOPMENT  AND  GROWTH  OF  THE  SKELETON. 

FIG.  27.  The    skeleton    at    its    earliest    period    is 

perceptible  as  a  soft  cell  structure,  which 
soon  assumes  the  more  consistent  char- 
acter and  composition  of  cartilage.  Ossi- 
fication, or  the  deposit  of  the  calcareous 
matters,  commences  as  early  as  the  sixth 
or  seventh  week  of  embryonic  life.  The 
process  occurs  from  one  or  more  points  for 
each  bone,  which  are  called  the  centres  of 
ossification.1 

Bones  of  simple  form  generally  have  but 
a  single  centre  of  ossification,  as  the  parietal 
and  the  carpal  bones.  The  others  are 
developed  from  a  number  of  centres,  in  most 
cases  holding  a  relationship  with  their 
degree  of  complexity.  Ossification  begins 
in  the  principal  part  of  a  bone,  which  is 
thence  called  the  diaph/ysis.2  The  accessory 
portions,  subsequently  ossifying  more  or  less  in 
succession,  are  called  epiph/yses,  Thus,  for 
example,  (figure  2t,)  the  shaft  or  diaphysis 
of  the  thigh-bone  first  begins  to  ossify,  then 
follow  in  succession,  as  epiphyses,  the  con- 
dyles,  the  head,  the  great  trochanter,  and 
finally  the  small  trochanter. 

In  a  vertebra,  (figures  28,  29,)  three  diaph- 
yses  simultaneously  undergo  ossification; 
that  is  to  say,  the  body  and  each  half  of  the 
arch.  Then  follow  the  epiphyses  together  of 
the  spinous  and  transverse  processes;  and 

lastly  a  thin  plate  of  bone  is  added  to  the  upper  and  lower  surface  of  the 

body. 

Epiphyses  are  united  with  their  diaphysis  by  continuous  cartilaginous 


FEMUR,  from  an  individual  about 
sixteen  years  of  age.  exhibiting  the 
diaphysis  (1,)  distinct  from  the  epiph- 
y8es,  (2,  3,  4  5.) 


Puncta  ossificationis. 


Body ;  corpus  ossis. 


THE  SKELETON. 


43 


structure,  which  remains  until  both  have  reached  their  full  development 
and  growth,  when  they  become  united  through  ossification  of  the  inter- 
vening cartilage. 


FIG.  29. 


FIG.  28. 


a 


DEVELOPMENT  OF  THE  VERTEBRAE,  a,  vertebra 
of  a  foetus,  in  a  cartilaginous  condition,  with  three 
centres  of  ossification;  1,  2,  lateral  pieces;  3,  the 
body ;  b,  vertebra  of  an  infant.  The  lateral  pieces, 
1,  2,  are  co-ossified  at  the  spinous  process,  and  join 
the  body  3,  at  the  sutures  4.  The  ends  of  the  trans- 
verse and  spinous  processes  yet  in  a  cartilaginous 
state. 


DEVELOPMENT  OF  THE  EPIPHYSES  TO  THE  VERTE. 
BRJE.  a,  dorsal  vertebra,  with  the  epiphyses  4,  5, 
to  the  transverse  processes;  6,  to  the  spinous  pro- 
cess; and  7,  to  the  body;  6, arch  with  its  processes; 
and  c,  body  of  a  lumbar  vertebra;  4,  5,  epiphyses 
of  the  transverse  processes;  6,  of  the  spinous  pro- 
cess; 7,  8,  of  the  body;  9,  10,  of  tubercles  of  the 
upper  articular  processes. 


Ossification  commences  in  the  skeleton  with  the  clavicle  and  lower  jaw 
as  early  as  the  sixth  or  seventh  week  of  embryonic  life  ;  it  then  occurs 
successively  in  the  vertebrae,  humerus,  femur,  ribs,  etc.  At  birth  the 
diaphyses  of  most  bones  are  ossified ;  but  none  of  the  epiphyses  ordin- 
arily have  commenced  the  process,  and  this  is  also  the  case  with  the  pa- 
tella and  the  carpal  and  tarsal  bones,  except  the  calcaneum  and  astragalus. 

Ossification  of  epiphyses  commences  with  that  of  the  condyles  of  the 
femur  about  the  period  of  birth ;  and  it  occurs  with  the  numerous  others 
of  the  skeleton  at  different  periods  up  to  adult  age. 

The  construction  of  bones  from  several  centres  of  ossification  faciltates 
the  development  of  complex  forms,  though  this  means  is  not  essential, 
for  we  find  corresponding  and  equally  complex  bones  in  other  animals 
developed  from  single  centres.  Thus  the  human  humerus,  which  is 
developed  from  seven  centres  of  ossification,  and  the  femur  from  five,  in 
birds,  many  lizards,  and  turtles,  are  developed  from  one. 

In  most  instances,  separate  centres  of  ossification,  or  groups  of  such  cen- 
tres, are  significant  of  permanently  distinct  bones  in  other  parts  of  the  same 
skeleton,  or  in  the  skeleton  of  other  animals.  Thus,  as  examples,  we 
recognize  the  epiphysis  of  the  olecranon  of  the  ulna  as  representing  the 
distinct  patella ;  the  coracoid  epiphysis  of  the  scapula  represents  the 
distinct  coracoid  bone  of  birds ;  the  five  divisions  of  the  sacrum  repre- 
sent as  many  true  vertebrae  :  in  whales,  dolphins,  and  serpents,  always 
remaining  as  separate  elements  in  the  vertebral  series. 


44  THE  SKELETON. 

The  presence  of  epiphyses,  and  the  intervening  plates  of  elastic  carti- 
lage to  the  diaphyses,  gives  an  important  incidental  condition  in  the  pro- 
tection of  the  body  from  injury  at  a  period  of  life  when  it  is  most  liable 
to  falls  or  blows.  Through  this  condition  the  shock  from  such  accidents 
is  much  lessened ;  and  the  jar,  which  if  communicated  to  the  large  and 
soft  growing  brain,  or  other  delicate  internal  organs,  might  impair  their 
structure,  is  much  weakened,  diffused,  or  intercepted.  Frogs  and  toads, 
which  from  their  remarkable  leaping  power  might  be  supposed  to  be 
liable  to  violent  concussions,  retain  epiphyses  to  the  long  bones  of  their 
limbs  almost  throughout  life ;  while  the  alligator  and  turtle,  which  in 
their  sprawling  condition  are  not  liable  to  falls,  have  the  long  bones  of 
their  limbs  developed  without  epiphyses. 

The  cartilage  of  the  embryonic  skeleton  consists  of  a  comparatively 
soft,  translucent,  opalescent,  homogeneous  or  faintly  granular  matrix, 
crowded  with  spherical  or  oval  cells,  which  have  finely  granular  contents 
and  a  central,  nucleolated  nucleus. 

In  the  progress  of  development  of  the  young  being,  the  cartilage  cells 
multiply  through  division,  and  the  intercellular  matrix  increases  so  as 
gradually  to  widen  the  spaces  between  the  groups  or  rows  of  cells. 

In  the  cartilaginous  diaphysis  of  long  bones,  the  cartilage  cells  mul- 
tiply in  linear  rows,  generally  parallel  with  one  another  and  with  the  long 
diameter  of  the  diaphysis.  In  epiphyses  and  short  bones,  the  cartilage 
cells  form  oblong  groups  irregularly  dispersed  from  the  centre. 

Just  previous  to  ossification  channels  become  developed  in  the  inter- 
cellular matrix  of  the  cartilage  by  resolution  of  its  substance,  and  blood- 
vessels extend  into  them  by  continuous  development  from  those  of  the 
exterior  investing  membrane. 

The  cartilage  at  the  centres  of  ossification  assumes  a  yellowish  hue 
and  an  indistinct  fibrous  appearance ;  and  at  this  time  the  chondrin  is 
either  converted  into,  or  displaced  by,  the  gelatinoid  element.  The 
calcareous  substances  are  now  deposited  in  the  intercellular  matrix  as 
minute  granules,  which  gradually  become  fused.  The  cartilage  cells 
likewise  receive  the  same  deposit,  and  their  walls  coalesce  with  the 
ossified  intercellular  matrix.  The  remaining  cavities  of  the  cells,  still 
filled  with  soft  contents,  constitute  the  lacunaB  of  bone.  A  few  of  the 
coarser  canaliculi  of  the  lacunae  appear  to  be  narrow  unossified  tracts, 
along  which,  perhaps,  there  are  comparatively  strong  currents  of  nutritive 
matter.  Most  of  the  canaliculi,  however,  apparently  originate  by  a 
subsequent  resolution  of  ossific  substance. 

The  diaphysis  of  long  bones  grows  in  length  by  continuous  develop- 
ment and  ossification  of  cartilage  at  the  extremities.  Hence  in  the 
experiment,  in  which  two  holes  are  bored  at  a  certain  distance  apart 


THE  SKELETON.  45 

in  the  shaft  of  a  long  bone  of  a  young  animal,  after  the  latter  has 
advanced  in  growth,  the  holes  are  found  to  remain  the  same  distance 
from  each  other,  while  the  shaft  has  increased  in  length  in  both  direc- 
tions. 

Tabular  bones  extend  in  a  similar  manner  at  their  borders ;  and  short 
bones  and  epiphyses  generally  in  all  directions  from  their  centres  of  ossi- 
fication. 

The  diaphysis  of  long  bones  grows  in  thickness  by  the  development 
from  the  under  surface  of  the  periosteum  of  successive  layers  of  a  sub- 
stance, at  first  resembling  incipient  fibrous  tissue,  but  subsequently  em- 
bryonic cartilage.1  In  the  latter  condition,  this  substance,  which  con- 
sists of  a  homogeneous  matrix  crowded  with  cartilage  cells,  and  pervaded 
with  vessels  from  the  periosteum,  undergoes  ossification  in  the  manner 
already  described. 

The  tabular  bones  of  the  cranial  vault  and  the  bones  of  the  face 
originate  from  the  fibrous  layers,  which  subsequently  constitute  their 
periosteum,  in  the  same  mode  that  the  outer  layers  of  the  diaphysis  of 
long  bones  are  produced,  as  just  described ;  and  they  afterwards  grow  in 
thickness  through  the  same  process. 

The  spongy  substance  of  the  bones  is  produced  by  a  resolution  of 
ossific  structure,  and  the  medullary  cavity  of  long  bones  is  formed  by  the 
gradual  solution  and  absorbtion  of  spongy  substance.  At  first  the  me- 
dullary cavities,  as  well  as  the  interspaces  of  the  spongy  substance,  are 
filled  with  a  nutritive  matter  and  numerous  nucleated  cells.  The  latter 
for  the  most  part  become  converted  into  the  adipose  cells  of  the  marrow 
of  the  medullary  cavities. 

At  birth,  the  canal  near  the  middle  of  the  shaft  of  long  bones, 
which  contains  the  principal  medullary  nutritious  vessels,  is  the  largest 
space  in  their  interior;  and  it  is  from  this  canal  that  the  medullary 
cavity  is  gradually  extended  by  absorption  of  the  spongy  substance 
occupying  the  axis  of  the  bone. 

As  the  diaphysis  of  the  long  bones  of  the  limbs  grows  in  length  through 
ossification  of  the  terminal  cartilage,  and  grows  in  thickness  through 
successive  deposits  from  the  periosteum,  the  medullary  cavity  increases 
almost  as  rapidly  by  absorption  of  previously  formed  osseous  tissue.  There- 
fore it  is,  before  such  a  bone  has  reached  its  full  growth,  it  appears  to 
have  been  repeatedly  absorbed  and  regenerated.  Thus  for  example,  the 
femur  at  the  period  of  birth  contains  none  of  the  osseous  tissue  of  this 
bone  in  the  embryo,  and  that  of  the  child  after  a  few  years  contains  none 

1  Which  differs  from  ordinary  cartilage  in  yielding  gelatin  instead  of  chondrin 
by  boiling. 


46  THE  SKELETON. 

of  the  osseous  tissue  which  existed  at  birth,  and  before  maturity  the 
bone  changes  several  times  again. 

After  bones  have  reached  their  full  growth,  calcareous  deposits  con- 
tinue still  to  be  made  gradually  throughout  life,  thus  rendering  them 
harder  and  more  brittle.  The  medullary  cavities,  and  also  in  a  less 
striking  manner  the  interspaces  of  the  spongy  substance,  slowly  increase 
in  size,  so  that  the  bones  of  old  persons  are  rendered  comparatively 
brittle  from  this  circumstance,  as  well  as  from  the  increase  of  calcareous 
deposits. 

ARTICULATIONS  OR  JOINTS  OF  THE  SKELETON. 

The  articulations  or  joints1  of  the  skeleton  exhibit  a  gradation  of 
union  from  those  which  are  immovable  to  such  as  possess  motion  in  all 
directions. 

The  most  immovable  articulations2  are  those  which  exist  between 
the  bones  of  the  skull,  constituting  what  are  called  the  sut'ures.3  Many 
of  the  sutures  are  formed  through  indentations  of  the  contiguous  mar- 
gins of  the  bones,  which  are  mutually  adapted  to  one  another,  often 
in  a  somewhat  dovetailed  manner.  From  their  toothed  appearance  they 
are  called  dent'ated  or  seriated  sut'ures.4  Examples  of  them  are  seen 
in  the  union  of  the  frontal,  parietal,  and  occipital  bones.  In  other 
sutures  the  contiguous  borders  of  bones  are  beveled  off  and  mutually 
coadapted,  as  observed  in  the  union  of  the  sphenoid  and  temporal 
bones  with  the  parietal.  Such,  from  their  scale-like  arrangement,  are 
called  squa'mous  sutures.5  In  some  sutures,6  plane  borders  of  contig- 
uous bones,  slightly  roughened,  are  coadapted,  as  in  the  union  of  the 
upper  maxillary  bones.  Occasionally  the  border  of  one  bone  is  grooved 
to  receive  the  sharpened  edge  of  another,7  as  in  the  articulation  of  the 
vomer  with  the  sphenoid  bone. 

The  next  form  of  articulation  possesses  more  or  less  flexibility 
without  allowing  other  motion.  Such  a  joint  is  called  a  sym'physis,8 
and  is  formed  by  the  union  of  broad  surfaces  of  contiguous  bones 
through  means  of  an  intervening  plate  of  nbro-cartilage.  Examples  of 
this  mode  of  junction  are  presented  in  the  union  of  the  bones  of  the 
pelvis,  the  bodies  of  the  vertebrae,  and  the  pieces  of  the  sternum. 

In  the  movable   articulations9  the  bones   have   their   opposed   sur- 

1  Arthroses.  6  Harmonia ;   harmony  ;  false  suture. 

2  Synarthroses.  7  Schindylesis. 

3  Suturae.  8  Amphiarthrosis. 

*  S.  dentatse;  s.  serratae.  9  Diarthroses  ;  dinrthrodial  articulations. 

5  S.  squamosse. 


THE  SKELETON.  47 

faces  invested  with  cartilage,  and  their  union  is  preserved  by  means  of 
ligaments,  which  inclose  the  joints.  Muscles  or  their  tendons,  which  in 
many  instances  more  or  less  surround  these  joints,  very  much  contribute 
to  the  firmness  of  their  union,  and  thus  to  prevent  dislocation  To  facili- 
tate movement,  they  are  lined  with  syno'vial  membrane,  which  secretes 
a  lubricating  liquid,  named  the  syno'via. 

Of  the  movable  articulations  there  are  several  varieties,  which  exhibit 
different  degrees  of  mobility. 

In  some  instances  the  movements  are  exceedingly  limited,  amounting 
only  to  a  slight  degree  of  gliding  of  the  opposed  surfaces  upon  each 
other,  as  instanced  in  most  of  the  joints  of  the  carpus  and  tarsus,  and 
those  of  the  articular  processes  of  the  vertebrae. 

In  other  cases  the  joints  are  restricted  to  a  hinge-like  motion,1  as  ob- 
served in  the  elbow  and  knee  joints,  and  those  of  the  fingers  and  toes.2 
The  hinge-like  movement,  together  with  a  motion  toward  either  side,  is 
observed  in  the  wrist  and  ankle  joints. 

Occasionally  joints  admit  only  of  a  rotary  motion,  as  in  the  two  radio- 
ulnar  articulations  and  those  between  the  atlas  and  axis. 

The  most  movable  articulations  are  the  ball-and-socket  joints,3  in 
which  the  head  of  one  bone  fits  into  a  more  or  less  deep  cup-shaped  con- 
cavity of  the  contiguous  bone.  Examples  of  such  joints  are  presented 
in  the  shoulder  and  hip.  The  movements  of  these  joints  are  those  of 
flexion  and  extension,  abduction  and  adduction,  circumduction  and  rota- 
tion. 

Of  the  different  movements  of  the  articulations,  flex'ion  is  that  in 
which  one  or  more  bones  of  a  joint  are  made  to  describe  an  angle  with 
others,  in  moving  either  backward  or  forward.  Thus  the  bending  of  the 
bones  of  the  forearm  forward,  is  the  flexion  of  the  forearm  upon  the 
arm ;  the  bending  of  the  leg  backward,  is  its  flexion  upon  the  thigh. 
Extension  is  the  opposite  movement  of  flexion,  in  which  the  bones  are 
generally  brought  into  a  line  with  one  another.  Thus  the  bending  of  the 
forearm  backward  after  it  has  been  flexed,  so  as  to  bring  it  on  the 
same  line  with  the  arm,  is  the  extension  of  the  forearm. 

Abduc'tion  is  that  movement  in  which  a  bone  is  directed  outwardly 
from  another,  or  from  the  body ;  and  adduction  is  the  opposite  move- 
ment, in  which  a  bone  is  directed  inwardly.  Thus  the  movement  by 
which  the  thumb  is  moved  outwardly  from  the  fingers  is  abduction,  and 
that  by  which  it  is  made  to  approach  them  is  adduction. 

CircTimduc'tion  is  that  motion  of  a  bone  when  its  head  acts  as  a  pivot 


1  Ginglymus  ;  ginglymoideus.  2  Ginglymoid  joints.  3  Enarthroses. 


48  THE  SKELETON. 

and  the  distal  end  is  made  to  describe  a  circle.  This  character  of  move- 
ment is  best  exemplified  with  the  humerus  and  glenoid  cavity  of  the 
scapula.  Rota'tion  is  the  motion  made  by  a  bone  when  it  rolls  on  its 
axis,  as  in  the  movements  of  the  radius  upon  the  ulna. 


OF  THE  RELATIVE  POSITION  OF  THE  DIFFERENT  STRUCTURES 
ENTERING  INTO  THE  COMPOSITION  OF  ARTICULATIONS. 

The  bones  articulating  by  suture  are  continuously  associated  by  inter- 
vening cartilage,  which  is  apt  to  ossify  after  the  bones  have  reached 
maturity.  The  fibrous  periosteum  in  all  cases  passes  over  the  sutures, 
resembling  in  this  position  the  capsular  ligaments  of  movable  joints.  In 
symphyses  an  intervening  plate  of  fibro-cartilage  intimately  connects  the 
surfaces  of  the  contiguous  bones ;  and  they  are  surrounded  with  bands 
of  fibrous  tissue,  corresponding  with  the  capsular  ligaments  of  movable 
articulations. 

In  movable  joints  the  opposed  surfaces  of  the  bones  are  invested  with 
a  layer  of  cartilage,  which  from  its  position  is  called  artic'ular  car'ti- 
lage.1  When  the  cartilage  covers  a  depressed  or  concave  surface,  it 
usually  becomes  thicker  toward  the  borders,  so  as  to  deepen  the  con- 
cavity ;  but  if  it  invests  a  head,  condyle,  or  other  articular  prominence, 
it  becomes  thinner  toward  the  margins. 

The  ligaments  surrounding  movable  joints  are  of  two  kinds :  the 
cap'sular2  and  band-like  lig'aments.3  The  former  are  cylindrical  sacs, 
including  by  their  extremities  the  borders  of  the  articular  surfaces 
of  bones,  where  they  become  continuous  with  the  periosteum  of  the 
latter,  and  frequently  with  the  contiguous  tendons  of  muscles.  They 
vary  in  thickness ;  are  composed  of  an  intertexture  of  bundles  of  fibrous 
tissue,  and  are  highly  flexible  and  slightly  extensible.  In  many  posi- 
tions, broad  tendons  of  muscles,  passing  over  joints,  assume  their  place, 
as  in  the  case  of  the  tendon  of  the  quadriceps  extensor  muscle  of  the 
thigh,  and  the  extensor  tendons  on  the  backs  of  the  phalangeal  articula- 
tions. The  band-like  ligaments  are  accessory  to  the  capsular  ligaments, 
contributing  to  the  strength  of  joints  in  particular  positions.  They  are 
strong  bundles  of  parallel  filaments  of^  fibrous  tissue,  quite  flexible,  but 
entirely  inextensible.  They  constitute  the  numerous  lateral  ligaments  of 
the  joints. 

The  syno'vial  mem'branes  belong  to  the  class  of  serous  membranes. 
They  line  the  interior  of  capsular  ligaments ;  and  in  the  adult  are  re- 
flected upon  the  border  of  the  articular  cartilages ;  but  in  infancy  they 

1  Diarthrodial  cartilage.  2  Capsulse  articulares.  3  Funicular  ligaments. 


THE  SKELETON.  49 

invest  the  entire  cavity  of  joints.  They  secrete  a  viscid,  albuminoid 
liquid  resembling  the  white  of  eggs,  and  called  the  syno'via,  which  lubri- 
cates the  surfaces  of  joints,  and,  by  lessening  friction,  facilitates  motion. 
The  synovial,  like  other  serous  membranes,  are  composed  of  a 
delicate  structureless  layer,  or  basement  membrane,  attached  beneath 
by  a  layer  of  connective  tissue,  in  which  blood-vessels  are  distributed, 
and  invested  on  the  free  surface  with  several  layers  of  pavement-like, 
nucleated  cells.  Their  inner  surface  is  smooth,  and  they  possess  no 
glands.  At  the  borders  of  joints  they  are  frequently  thrown  into  folds 
and  processes,  containing  connective  tissue,  fat,  and  an  occasional  isolated 
cartilage  cell.  These  syno'vial  fringes1  apparently  act  as  cushions  to 
fill  up  interspaces,  though  from  their  greater  comparative  vascularity 
than  other  portions  of  the  membrane,  they  are  no  doubt  especially 
active  in  the  production  of  synovia. 

Concave  articular  surfaces  are  frequently  rendered  deeper  by  the  pro- 
vision of  a  band  of  fibro-cartilage  tipping  or  surrounding  their  margin, 
as  in  the  case  of  the  glenoid  cavity  of  the  shoulder  and  the  acetabu- 
lum  of  the  hip-joint.  Occasionally  joints  are  partially  or  completely 
divided  into  two  parts  by  the  introduction  of  an  inter-articular  fibro- 
cartilaginous  disk,  as  in  the  case  of  the  articulation  of  the  lower  jaw  and 
the  knee-joint. 

In  some  instances  bones  are  connected  by  ligaments  totally  different 
from  the  ordinary  ones,  being  composed  of  an  elastic  substance ;  such 
are  the  yellow  ligaments  which  conjoin  the  vertebral  arches ;  and  such 
also  is  the  nature  of  the  nuchal  ligament  which  sustains  the  head  of 
quadrupeds. 

The  various  structures  which  have  been  mentioned  as  entering  into  the 
composition  of  the  articulations  consist  of  bones,  cartilages,  fibro-carti- 
lages,  ligaments,  and  synovial  membranes.  The  constitution  of  bones  or 
of  the  osseous  tissue  has  been  described,  but  a  consideration  of  the 
tissues  comprising  the  remaining  structures  is  deferred  at  present,  on 
account  of  their  entering  into  the  constitution  of  many  other  organs. 
The  structure  of  the  cartilages  and  nbro-cartilages  will  be  found  under 
their  appropriate  head;  the  structure  of  ligaments  in  the  description 
of  the  white  fibrous,  and  yellow  elastic  tissues ;  and  the  synovial  mem- 
branes are  again  mentioned  in  the  account  of  the  serous  membranes. 

1  Synovial  glands  of  Havers ;  Haversian  glands ;  glandulae  articulares ;  synovial 
fimbrise. 

4 


50 


THE  SKELETON. 


BONES  OF  THE  HEAD  OR  SKULL. 

The  bones  of  the  head  or  skull  are  twenty-two  in  number,  and  with 
one  exception,  that  of  the  lower  jaw,  are  firmly  and  immovably  articu- 
lated. They  form  together  cases  for  the  reception  and  protection  of  the 
brain,  the  organs  of  especial  sense,  and  the  commencement  of  the 
alimentary  and  respiratory  passages.  They  are  divisible  into  two 
groups :  those  of  the  cranium  or  brain  case,  eight  in  number,  and  those 
of  the  face,  fourteen  in  number. 

BONES  OF  THE  CRANIUM. 

Of  the  eight  bones  of  the  cranium,  four  are  single  and  symmetrical : 
the  occipital,  sphenoid,  ethmoid,  and  frontal  bones,  situated  at  the  occi- 
put, base,  and  forehead.  The  other  bones  are  in  pairs :  the  parietal 
and  temporal  bones,  situated  at  the  top  and  sides  of  the  cranium. 

THE  OCCIPITAL  BONE. 

The  Occip'ital  bone1  occupies  the  posterior  extremity  of  the  cranium, 
FIG.  30.  FIG.  31. 


EXTERNAL  VIEW  OF  THE  OCCIPITAL  BONE.  1,  su- 
perior curved  line ;  2,  external  occipital  protuber- 
ance; 3,  occipital  crest;  4,  inferior  curved  line;  5, 
occipital  foramen;  6,  condyle;  7,  fossa  behind  the 
condyle,  in  which  a  venous  foramen  frequently 
opens;  8,  position  of  condyloid  foramen;  9,  trans- 
verse process ;  10,  notch  contributing  to  form  the 
jugular  foramen;  11,  basilar  process. 


INTERNAL  VIEW  OP  THE  OCCIPITAL  BONE.  1,  fossa 
for  the  cerebrum;  2,  fossa  for  the  cerebellum;  3-6, 
occipital  cross;  3,  groove  for  the  longitudinal 
sinus ;  4,  ridge  for  the  attachment  of  the  cerebellar 
falx;  5,  groove  for  the  lateral  sinus;  6,  internal  oc- 
cipital protuberance;  7,  occipital  foramen;  8,  ba- 
silar process;  9, 10,  groove  for  the  lateral  sinus,  de- 
scending on  the  transverse  process  to  the  jugular 
notch;  11,  border  for  the  parietal  bone;  12,  bor- 
der for  the  temporal  bone ;  13,  position  at  which 
the  ninth,  tenth,  and  eleventh  cerebral  nerves  pass 
through  the  jugular  foramen;  14,  condyloid  fora- 
men. 


1  Os  occipitis;  os  puppis;  os  memorise;  os  basilare;  part  of  the  os  spheno-basil- 
are  ;  os  lambdoides ;  os  nervosum ;  os  prorse  ;  os  pyxidis ;  os  laudge  ;  os  fibrosum ; 
os  pelvicephalicum  ;  os  sextum  cranii. 


THE   SKELETON.  51 

extending  forward  into  the  base  of  the  latter.  It  has  a  general  quadrate 
outline,  with  a  convex  external  and  a  concave  internal  surface. 

Its  lower  portion  presents  a  large  oval  aperture,  the  occipital  fora'- 
men,1  which  gives  transmission  to  the  spinal  cord,  the  spinal  accessory 
nerves,  and  the  vertebral  arteries. 

In  advance  of  the  foramen  is  a  thick  plate,  the  bas'ilar  proc'ess,2  the 
lateral  borders  of  which  are  rough  and  contiguous  to  the  petrous  por- 
tion of  the  temporal  bone;  and  its  anterior  extremity  is  rough  and  con- 
nected with  the  body  of  the  sphenoid  bone  by  means  of  an  intervening 
plate  of  cartilage.  The  latter  ossifies  about  the  age  of  puberty,  thus 
associating  the  occipital  and  sphenoid  bones  into  one  piece.3  The 
upper  surface  of  the  basilar  process  is  a  smooth,  shallow  groove,4 
inclining  to  the  occipital  foramen,  and  supporting  the  medulla  oblongata. 
The  under  surface5  is  impressed  by  muscular  attachments,  and  overhangs 
the  pharynx. 

On  each  side  of  the  occipital  foramen  anteriorly,  and  on  the  under 
part  of  the  bone,  are  situated  the  con/dyles.  These  are  two  oblong 
prominences,  converging  forward,  with  their  lower  surface  convex, 
inclined  outwardly,  and  covered  with  cartilage.  Between  them  and  the 
corresponding  articulating  processes  of  the  atlas,  the  backward  and  for- 
ward movements  of  the  head  occur.  At  their  inner  border,  they  are 
roughened  for  the  attachment  of  ligaments. 

Piercing  the  bone,  above  the  middle  of  the  condyles,  from  within  out- 
wardly, is  the  con/dyloid  fora'men,6  for  the  transmission  of  the  hypo- 
glossal  nerve.  Frequently  at  the  back  of  the  condyles  there  is  another 
foramen,7  for  the  transmission  of  a  vein. 

To  the  outer  side  of  the  condyles  is  an  angular  prominence,  the  trans'- 
verse  proc'ess,  which  presents  a  ridge8  below  for  muscular  attachment, 
a  groove  above  to  accommodate  the  termination  of  the  lateral  sinus,  and 
an  articular  surface  at  the  extremity  covered  with  cartilage.  In  front  of 
the  process  is  a  wide  notch,  which,  with  the  contiguous  border  of  the 
temporal  bone,  forms  the  ju/gular  fora'men,  for  the  conjunction  of  the 
lateral  sinus  with  the  jugular  vein  and  the  transmission  of  the  spinal 
accessory,  pneunio-gastric,  and  glosso-pharyngeal  nerves. 

The  upper  expanded  portion  of  the  bone  is  convex  externally,  and 

1  F.  occipitale  magnum  ;  f.  magnum.  5  Basilar  surface. 

2  Pars  basilaris;  body  of  the  occipital  6  Anterior  condyloid  foramen, 
bone;    basi-occipital    bone;     processus          7  Posterior  condyloid  foramen, 
cuneiformis.  8  Jugular  tubercle,  or  paramastoid  pro- 

3  Os  basilare ;  os  spheno-occipitale.  cess  of  lower  animals. 

4  Basilar  fossa. 


52  THE   SKELETON. 

presents  just  above  its  centre  the  external  occip'ital  protuberance. 
From  this  a  ridge,  the  occip'ital  crest,1  descends  to  the  occipital  fora- 
men and  gives  attachment  to  the  nuchal  ligament.  From  the  protuber- 
ance there  extends  outwardly  the  superior  curved  line,2  so  called  in 
contradistinction  to  another  lower  down,  the  inferior  curved  line,3 
These  lines,  which  are  only  well  marked  in  well-developed  muscular  indi- 
viduals of  mature  age,  together  with  the  surfaces  between  and  below 
them,  give  attachment  to  the  muscles  which  sustain  the  erect  position  of 
the  head. 

The  inner  surface,  of  the  expanded  portion  of  the  bone,  is  divided  by 
ridges,  forming  the  occip'ital  cross,  into  four  broad,  shallow  fossee,  of 
which  the  lower  two  accommodate  the  hemispheres  of  the  cerebellum, 
and  the  upper  two  the  posterior  lobes  of  the  cerebrum.  The  prominent 
centre  of  the  cross  is  the  internal  occip'ital  protu'berance,  which  is 
situated  a  little  lower  than  the  external  one. 

The  upper  limb  of  the  occipital  cross  is  marked  by  a  groove  indicating 
the  course  of  the  terminal  portion  of  the  longitudinal  sinus ;  and  it  has 
attached  to  it  the  posterior  extremity  of  the  cerebral  falx  of  the  dura 
mater.  The  lower  limb,  extending  to  the  occipital  foramen,  has  the 
cerebellar  falx  attached  to  it.  The  lateral  limbs  are  marked  with 
grooves  indicating  the  course  of  the  lateral  sinuses  and  the  attachment 
of  the  tentorium. 

The  superior  borders  of  the  bone  are  dentated,  and  converge  to  form 
the  occip'ital  angle,  which  is  received  between  the  parietal  bones.  The 
lateral  borders  inferiorly  articulate  with  the  mastoid  portions  of  the  tem- 
poral bones. 

The  upper  extremity  of  the  occipital  bone  is  occasionally  found 
to  be  separated  from  the  other  portion  by  a  transverse  suture  at  any 
position  down  to  the  superior  curved  line.  Such  an  anomalous  piece 
corresponds  with  the  interparietal  bone  of  certain  of  the  lower  animals,  as 
many  rodents  and  ruminants.  Occasionally  the  anomalous  human  inter- 
parietal  bone  is  divided  in  the  median  line  into  two  parts. 

THE   SPHENOID  BONE. 

The  Sphe'noid  bone4  is  situated  across  the  base  of  the  cranium,  and 
extended  up  on  each  side,  just  in  advance  of  the  middle.  It  contributes 

1  Occipital  spine.  tiforme;  os  azygos;  os  inconjugatum ;  os 

2  Superior  semicircular  ridge.  alatum;  osalaeforme;  os  polymorphon  ; 
8  Inferior  semicircular  ridge.  os  pterygoideum ;  os  colatorii ;  os  cuneo 
*  Os  'sphenoideum ;    os  sphecoideum  ;  comparatum ;  sphenoidal  part  of  the  os 

os  cuneiforme ;  os  vespiforme ;  os  basil-  spheno-basilare,  or  of  the  os  spheno- 
are;  os  baxilare ;  ospapillare;  os  mul-  occipitalis. 


THE  SKELETON. 


53- 


FIG.  32. 


to  the  formation  of  the  cranial  cavity,  the  orbits,  and  the  temporal, 
spheno-maxillary,  and  nasal  fossae. 

From  its  complex  form  we  may  examine  in  succession  its  body,  its 
small  and  great  wings,  its  pterygoid  processes,  and  its  foramina. 

The  body1  or  central  portion  of  the  bone  is  irregularly  cuboidal,  and 
articulates  posteriorly  by 
a  rugged  surface,  in  the 
manner  previously  men- 
tioned, with  the  occipital 
bone.  Its  upper  surface 
presents  a  deep  excava- 
tion, the  pitu/itary  fos- 
sa,2 which  lodges  the  pi- 
tuitary body  of  the  brain. 
Posteriorly  the  fossa  is 
bounded  by  an  oblique 

plate,        the       dCCliv'ity,3         FRONT  VIEW  OF  THE  SPHENOID  BONE.    1,  2,  sphenoidal  crest  and 
whioh  rontinnps  the  slone    rostrum  for  J°inins  the  nrtsal  Plate  of  the  ethmoid  bone  and  the 

10Pe      vomer;  3,  entrance  of  the  sphenoidal  sinuses;  4,  small  wing;  5, 
Of  the   basilar    prOCeSS    Of     Optic  foramen  piercing  its  base ;  6,  sphenoidal  foramen;  7,  rotund 

the   occipital    bone,    and 
supports  the  pons.     The 
convex     prominence     in 
front,     is     the     olivary 
proc'ess,4  upon  the  slight- 
ly depressed  surface  of  which  the  commissure  of  the  optic  nerve  rests. 
In  advance  of  this,  is  a  smooth  surface  inclining  toward  the  ethmoid 
bone,  with  which  it  articulates  by  its  anterior  border. 

The  prominent  angles  of  the  declivity  are  called  the  posterior  cli'noid 
processes,5  in  contradistinction  to  the  obtuse,  backward  projections,  of 
the  small  wings,  called  the  anterior  cli'noid  processes.5 

On  each  side  of  the  body,  below  the  pituitary  fossa,  there  is  a  shallow 
groove,6  for  the  accommodation  of  the  internal  carotid  artery,  which 
curves  from  a  notch  at  the  back  of  the  bone  to  the  interval  between  the 
anterior  clinoid  and  olivary  processes. 

The  inferior  surface  of  the  body,  which  overhangs  the  posterior  nares, 


foramen;  8,  orbital  surface  of  the  great  wing;  9,  temporal  sur- 
face of  the  same;  10,  ridge  separating  the  temporal  and  spheno- 
maxillary  fossae;  11,  position  of  the  pterygo-palatine  canal;  12, 
pterygoid  canal;  13,  internal  pterygoid  process,  ending  in  a  hook 
14;  15,  external  pterygoid  process;  16,  spinous  process;  17,  oval 
foramen;  18,  spi nous  foramen. 


1  Basisphenoidbone;  posterior  or  prin- 
cipal sphenoid  bone ;  basis  sive  corpus 
partis  sphenoidalis  ossis  spheno-occipi- 
talis. 

2  Sella  turcica;  s.  equina;  ephippium. 


3  Dorsum  ephippii;  clivus;  clivus  Blu- 
menbachii. 

4  Tuberculum  ephippii. 

5  Processus  clinoidei  posteriores  et  an- 
teriores ;  apophyses  clinoides. 

6  Sulcus  caroticus.  'tHcJ 


54 


THE   SKELETON. 


FIG 


presents  a  median  acute  ridge,  the  ros'trum,1  with  which  the  expanded 
border  of  the  vomer  articulates ;  and  on  each  side  is  a  thin  projecting 
plate,  which  joins  the  reflected  margin  of  the  same  bone. 

The  anterior  surface,  directed  toward  the  nasal  fossae,  presents  a  median 
ridge,  the  sphe'noidal  crest,2  which  articulates  with  the  nasal  plate  of 
the  ethmoid  bone.  On  each  side  of  the  crest  is  an  opening  communicating 
with  the  sphe'noidal  sinuses,3  which  are  two  large  cavities  hollowed  in 
the  interior  of  the  body,  and  separated  by  a  usually  unsymmetrical  par- 
tition. 

In  infancy  the  sphenoidal  sinuses  do  not  exist ;  and  the  body  then 
presents  inferiorly  a  thick  median  ridge,  with  a  triangular  space  on  each 
side.  These  spaces  receive  a  pair  of  hollow  cones,4  projecting  from  the 
ethmoid  bone,  which  subsequently  coalesce  with  the  sphenoid  bone 
and  detach  themselves  from  the  former,  thus  producing  the  sphenoidal 
sinuses. 

The  small  wings5  of  the  sphenoid  bone  are  two  sabre-like  processes, 

which  extend  horizontally 
outward  from  the  antero- 
lateral  portion  of  the  body. 
Their  anterior  rugged  bor- 
der articulates  with  the 
orbital  plates  of  the  fron- 
tal bone ;  and  their  pos- 
terior smooth  and  curved 
border  is  received  into  the 
fissure  separating  the  an- 
terior and  middle  lobes  of 
the  cerebrum.  Their  outer 
end  is  sharp  pointed ;  and 
their  posterior  end  forms 
the  blunt  anterior  cli'noid 
process. 

The  great  wings6  pro- 
ject   laterally    from    the 
body,  curve  outward,  for- 
ward, and  upward,  and  present  three  important  surfaces.      The  superior 


UPPER  VIEW  OP  THE  SPHENOID  BONE.  1,  pituitary  fossa;  2, 
olivary  process;  3,  declivity;  4,  anterior  clinoid  process;  5,  pos- 
terior clinoid  process;  6,  posterior  border  of  the  body;  7,  cerebral 
surface  of  the  great  wing;  8,  articular  surface  for  the  frontal 
bone ;  9,  articular  border  for  the  temporal  bone ;  10,  spineus  pro- 
cess; 11,  small  wing;  12,  border  articulating  with  the  orbital 
plate  of  the  frontal  bone;  13.  border  joining  the  ethmoid  bone; 
14,  optic  foramen ;  15,  sphenoidal  foramen ;  16,  rotund  foramen ; 
17,  oval  foramen;  18,  spinous  foramen;  19,  groove  for  the  internal 
carotid  artery. 


1  Processus  azygos. 

2  Crista  or  spina  sphenoidalis. 

3  Sinus  sphenoidales. 

4  Ossicula   Berlin! ;    cornua   sphenoi- 


dalia;  pyramids  of  Wistar;  ossa  triangu- 
laria. 

5  Alae  minores;  processus  enciforoies; 
apophyses  Ingrassii. 

6  Alao  magnse,  temporal  wings. 


THE  SKELETON.  55 

or  cer'ebral  surface1  is  a  crescentic  concavity  contributing  to  form  the 
middle  cerebral  fossa.  The  anterior  or  orVital  surface2  is  an  oblique 
quadrate,  vertical  plane,  forming  part  of  the  outer  wall  of  the  orbit. 
The  external  or  temporal  surface3  is  divided  by  a  ridge  into  two  parts, 
of  which  the  upper,  slightly  concave  and  directed  outwardly,  forms  part 
of  the  temporal  fossa,  while  the  lower  division  directed  downward  forms 
part  of  the  spheno-maxillary  fossa. 

From  the  back  part  of  the  great  wing  projects  the  thick,  angular, 
spinous  process,4  which  is  received  in  the  interval  between  the  squamous 
and  petrous  portions  of  the  temporal  bone. 

Upon  the  broad  rough  surface  inclining  from  the  summit  of  the  great 
wing  forward,  rest  the  anterior  prolonged  angle  of  the  parietal  bone 
and  the  orbital  plate  of  the  frontal  bone.  The  anterior  border  of  the 
orbital  surface  articulates  with  the  malar  bone,  and  its  lower  border 
forms  the  upper  boundary  of  the  spheno-maxillary  fissure.  The  posterior 
concave  border  of  the  great  wing  joins  the  squamous  portion  of  the  tem- 
poral bone. 

The  pter'ygoid  proc'esses5  project  vertically  downward  from  the  junc- 
tion of  the  great  wings  with  the  body.  They  consist  of  a  pair  of  plates 
united  at  an  angle  anteriorly,  and  diverging  posteriorly,  so  as  to  inclose 
an  angular  groove,  the  pter'ygoid  fossa.6  The  external  pter'ygoid  pro- 
cess is  broad  and  thin,  and  directed  outward  and  backward.  The  inter- 
nal pter'ygoid  process  is  longer  and  narrower  than  the  other ;  and  it 
forms  the  lateral  border  of  the  posterior  nares.  At  its  upper  part  behind 
is  a  fossa7  for  the  origin  of  the  tensor  muscle  of  the  palate ;  and  its  lower 
part  is  prolonged  into  a  hook8  around  which  the  tendon  of  the  latter 
muscle  turns  in  its  course  to  the  palate.  The  pterygoid  fossa  at  its  lower 
part  presents  a  deep  angular  notch,9  which  is  occupied  by  the  pyramidal 
process  of  the  palate  bone. 

The  foramina  of  the  sphenoid  bone  are  numerous  and  important. 

The  op'tic  fora'men10  pierces  the  base  of  the  small  wing  from  the  side 
of  the  olivary  process  outward  and  forward.  It  transmits  the  optic 
nerve  and  ophthalmic  artery  from  the  cranial  cavity  to  the  orbit. 

The  sphenoid'al  fora'men11  in  the  separated  bone  is  open  at  its  outer 
end,  but  is  closed  by  the  apposition  of  the  frontal  bone.  It  is  club- 

1  Superficies  cerebralis  ;  s.  interna.  7  Scaphoid  fossa. 

2  S.  orbitalis;  s.  anterior.  8  Hamuluspterygoideus;  hamular  pro- 

3  S  temporalis ;  s.  externa.  cess. 

4  Lamina   triangularis ;    spina    angu-  9  Incisura  pterygoidea  ;  fissura  ptery- 
laris.  goidea. 

5  Processus  pterygoidea  ;    aloe  inferi-  10  Foramen  opticum. 

ores;  a.  palatinae;  processus  aliformes.  n  F.  sphenoidalis;  f.  orbitalis  superior ; 

6  Fossa  pterygoidea.  f.  lacerum  superius. 


56  THE  SKELETON. 

shaped,  with  the  broad  end  internal,  and  separates  the  small  and  great 
wings.  It  opens  into  the  orbit  and  transmits  the  occulo-motor,  pathetic, 
ophthalmic,  and  abducent  nerves,  and  the  ophthalmic  vein. 

The  rotund'  fora'men1  pierces  the  great  wing  from  behind  forward, 
just  below  the  inner  extremity  of  the  preceding  foramen.  It  opens  from 
the  cerebral  surface  into  the  pterygo-m  axillary  fossa,  and  transmits  the 
superior  maxillary  nerve. 

The  oval  fora'men,2  larger  than  the  last,  and  less  than  half  an  inch 
behind  it,  pierces  the  great  wing  vertically,  and  transmits  the  inferior 
maxillary  nerve. 

The  spinous  fora'men,3  quite  near  the  preceding,  pierces  the  spinous 
process  vertically,  and  transmits  the  great  meningeal  artery. 

The  pter'ygoid.  canal4  penetrates  the  root  of  the  pterygoid  processes 
from  before  backward,  and  transmits  the  pterygoid  nerve. 

The  pter'ygo-pal'atine  canal5  is  a  small  groove  situated  internally  to 
the  former,  and  converted  into  a  complete  canal  by  the  apposition  of  the 
palate  bone. 

THE  ETHMOID   BONE. 

The  Eth'moid  bone6  is  situated  at  the  anterior  part  of  the  base  of  the 
cranium,  between  the  cavity  of  the  latter  and  the  nasal  fossae,  and  between 
the  orbits.  It  is  cuboidal  in  form,  and  is  exceedingly  light,  in  conse- 
quence of  its  excavated  character. 

We  may  consider,  separately,  its  vertical  lamina,  its  cribriform  plate, 
and  its  lateral  masses. 

The  vertical  lamina  occupies  the  median  line.  Its  upper  portion,  pro- 
jecting into  the  cavity  of  the  cranium,  is  the  ethmoid'al  crest,7  which  is 
thick  and  prominent  in  front,  and  rapidly  declines  posteriorly.  It  sepa- 
rates the  ethmoidal  gutters,  and  has  attached  the  anterior  extremity  of 
the  cerebral  falx.  From  its  front  project  the  ethmoid'al  wings,8  two 
small  processes  resting  against  the  frontal  bone. 

The  lower  four-fifths  of  the  vertical  lamina  form  the  na'sal  plate,9 
which  contributes  about  one-third  to  the  extent  of  the  nasal  partition. 
Its  posterior  border  joins  the  sphenoidal  crest ;  its  inferior,  the  vomer ; 
and  its  anterior  below,  the  triangular  cartilage ;  and  above,  the  nasal 
process  of  the  frontal  bone.  Its  superior  border  on  each  side  is  pierced 
by  vertical  canals,  for  the  passage  of  branches  of  the  olfactory  nerves. 

1  F.  rotundum.  spongiosum;  os  cristatum;  os  cubicum; 

2  F.  ovale.  os  colatorium ;    os  foraminulentum  ;  os 
8  F.  spinosum.  coliforme :  os  multiforme. 

4  Canalis  pterygoideus;  c.  Vidianus.  7  Crista  ethmoidalis ;  crista  galli. 

5  Canalis  pterygo-palatinus.  8  Processus  alares. 

6  Os  ethmoideum  ;    os  cribrosum  ;    os          9  Lamella  nasalis. 


THE   SKELETON. 


57 


FIG.  34. 


si'nuses,3  which   are   usually  separated  into 


three   sets : 
terior. 


the   anterior,  middle,   and   pos- 


The  criVrifonn  plate1  is  the  horizontal  perforated  portion  connecting 
the  lateral  masses  with  the  vertical  lamina,  and 
occupying  the  interval  of  the  orbital  plates  of 
the  frontal  bone.  It  separates  the  cavity  of  the 
cranium  from  the  nasal  fossae,  and  is  depressed 
on  each  side  of  the  ethmoidal  crest,  so  as  to 
form  the  ethmoid'al  gutters,  for  the  lodg- 
ment of  the  olfactory  bulbs.  Its  numerous 
orifices2  transmit  the  nerves  from  the  latter, 
except  the  larger  anterior  one,  which  gives 
passage  to  the  nasal  branch  of  the  ophthalmic 
nerve. 

The  lateral  masses  consist  of  an  aggrega- 
tion of  thin  walled  cavities,  the  ethmoid'al 

UPPER  VIEW  OF  THE  ETHMOID  BONE 

1,  orbital  surface  of  the  lateral  mass; 

2,  posterior  extremity  of  the  cribri- 

They  are  bounded  externally  by  the   fa™  &**#> which  unite8  the  lateral 

,.._,.  i  •    i    /•  />  j.i        •  masses,  and  is  depressed   and  perfo- 

orbital  plate,4  which  forms  part  of  the  inner   rated  with  numerou3  foramina  on 

Wall  Of  the    Orbit.       The    plate    is    Square,  but    each  side  of  the  ethmoidal  crest  3;  the 
.   ,  fy,    .       , ,  .  i  11  j -i         two  oblique  processes  in  advance  of 

not  being  sufficiently  extensive  to  close  all  the   the  latter  are  the  ethmoidal  wings; 

Sinuses,  this  is  done  in  front   by  the  lachrymal    4,  anterior  extremity  of  the  nasal 

and  maxillary  bones,  above  by  the  borders  of  plate;  5'th' 

the  orbital  plates  of  the  frontal  bone,  and  behind  by  the  sphenoid  and 

palate  bones. 

The  inner  or  nasal  surface  of  the  lateral  masses  presents  two  oblique, 
scroll-like  laminae,  the  superior  and  inferior  tur'binated  proc'esses.5 
The  former  is  posterior,  shorter  than  the  other,  and  is  thin  and  narrow. 
The  latter  extends  the  length  of  the  lateral  mass,  and  presents  a  convex 
surface  toward  the  nasal  partition,  a  concave  surface  toward  the  eth- 
moidal sinuses,  and  a  convoluted  and  rough  border  downward.  Between 
the  turbinated  processes  is  an  oblique  fissure,  the  superior  mea'tus6 
of  the  nose,  into  which  opens  the  posterior  and  middle  ethmoidal 
sinuses.  Above  the  processes,  the  surface  is  perforated  by  branches  of 
the  olfactory  nerve.  The  inferior  turbinated  process  forms  the  upper 
boundary  of  the  middle  mea'tus7  of  the  nose,  into  which  opens  the 
anterior,  and  sometimes  the  middle  ethmoidal  sinuses. 


1  Lamina  cribrosa. 

2  Foramina  cribrosa. 

3  Cellulae  ethmoidales. 

4  Os  planum ;  lamina  papyracea. 

5  Superior     and     middle     turbinated 


bones ;  concha  sup.  et  inf. ;  c.  minor 
et  major;  ossa  spongiosa  sup.  et  medius; 
superior  and  middle  spongy  bones. 

6  Meatus  narium  superior. 

7  M.  n.  medius. 


58 


THE   SKELETON. 


From  the  lower  portion  of  the  lateral  mass,  where  it  rests  upon  the 
maxillary  bone,  one  or  two  small  irregular  plates1  project  downward  so 
as  to  diminish  the  size  of  the  aperture  of  the  maxillary  sinus. 


FIG.  35. 


THE  FRONTAL  BONE. 

The  Front'al  bone2  is  situated  at  the  anterior  part  of  the  cranium,  and 

forms  the  basis  of  the  forehead,  the 
root  of  the  nose,  and  the  roofs  of 
the  orbits. 

Externally  it  is  convex  and 
smooth,  and  presents  on  each  side 
the  front'al  eminence,3  usually  the 
most  prominent  part  of  the  fore- 
head, and  especially  well  marked 
in  the  young. 

At  the  lower  border  of  the  bone 
on  each  side  is  an  arching  ridge, 
the  supra-orbital  margin,  the  ex- 
tremities of  which  terminate  in  the 
external*  and  internal  angular 
processes.  At  the  inner  part  of 
the  ridge  is  a  foramen,  or  a  notch 
converted  into  one  by  a  ligament, 
the  supra-orb'ital  fora'men,  which 
transmits  an  artery  and  nerve  to 
the  forehead. 

Above  the  supra-orbital  margin  is  an  arching  prominence,  the  super- 
ciliary ridge,5  which  is  situated  just  above  the  eyebrow,  and  varies  in 
degree  of  development  in  different  individuals.  The  prominence  between 
the  ridges  of  the  two  sides  is  the  nasal  eminence,6  the  width  of  which 
has  much  influence  in  the  intellectual  expression  of  the  face.  Below,  it 
terminates  at  the  root  of  the  nose,7  which  is  a  rough  surface,  for  articu- 
lating with  the  nasal  and  maxillary  bones.  From  this  surface  projects 
the  nasal  spine,8  which  serves  as  a  point  of  support  to  the  nasal  bones, 
and  joins  behind  the  nasal  plate  of  the  ethmoid  bone. 


EXTERNAL  VIEW  OF  THE  FRONTAL  BONE.  1,  situa- 
tion of  the  frontal  eminence;  2,  situation  of  the 
superciliary  ridge;  3,  supra-orbital  margin;  4,  5, 
external  and  internal  angular  processes;  6,  supra- 
orbital  notch  or  foramen;  7,  nasal  eminence;  8, 
temporal  ridge ;  9,  nasal  spine. 


1  Processus    uncinatus;    p.    Blumen- 
bachii. 

2  Os  sincipitis;  os  coronale;  os  prorae; 
os  puppis;  osrationis;  os  inverecundum. 

3  Tuber  frontalis;    frontal  protuber- 
ance. 


4  Processus  zygomaticus. 

5  Arcus  superciliaris. 

6  Nasal   tuberosity  ;    glabella ;    inter- 
cilium;  met  opium;  mesophryon. 

7  Pons  nasalis. 

8  Spina  nasalis  superior. 


THE   SKELETON. 


59 


FIG.  36. 


At  the  side  of  the  bone,  curving  upward  and  backward  from  the 
external  angular  process,  is  the  tem'poral  ridge,  which  includes  the 
anterior  part  of  the  temporal  fossa. 

The  internal  surface  of  the  frontal  bone  is  generally  concave  and 
impressed  by  the  convolutions  of  the  cerebrum.  In  its  middle  below  is 
a  ridge,  the  front/al  crest,1  which 
gives  attachment  to  the  cerebral 
falx,  and  disappears  above  at  the 
sides  of  a  shallow  groove  for  ac- 
commodating the  longitudinal  sinus. 
At  the  bottom  of  the  crest  is  a 
blind-pit,2  or  a  canal,3  transmitting 
a  vein  from  the  nose  to  the  latter 
sinus. 

From  the  lower  part  of  the  in- 
ternal surface  project  the  two  broad, 
arching  orb'ital  plates,4  which  form 
the  roofs  of  the  orbits.  They  are 
separated  by  a  wide  interval,  the 
ethmoid'al  fissure.5  Above,  they 
are  convex,  and  strongly  marked 
by  the  inferior  convolutions  of  the 
anterior  cerebral  lobes.  Below, 
they  are  concave  and  smooth,  and 
are  deeply  depressed  within  the 
position  of  the  external  angular 
process  for  the  accommodation  of 
the  lachrymal  gland.6  Just  above 
the  internal  angular  process,  on  the 
same  surface,  is  a  small  impression,7 
made  by  the  fibro-cartilaginous 
pulley  of  the  superior  oblique 
muscle  of  the  eyeball. 

The  outer  border  of  the  orbital  plate  and  the  external  angular  process 
articulate  with  the  malar  bone ;  and  the  posterior  border  of  the  former 
joins  the  small  wing  of  the  sphenoid  bone.  Its  inner  border  exhibits 
several  superficial  excavations,  which  form  the  upper  boundary  of  the 
ethmoidal  sinuses,  and  in  front  of  them  is  the  communication  with  the 


INTERNAL  VIEW  OF  THE  FRONTAL  BONE.  1,  com- 
mencement of  the  groove  for  the  longitudinal 
sinus,  formed  by  the  divergence  of  .the  frontal 
crest ;  2,  is  placed  in  the  ethmoidal  fissure,  and 
points  to  a  small  venous  canal;  3,  superior  dentated 
border,  articulating  with  the  parietal  bones;  4,  pos- 
terior border  of  the  orbital  plate  5,  which  joins  the 
small  wing  of  the  sphenoid  bone ;  6,  irregular  inner 
border  of  the  same  plate  which  covers  the  upper 
part  of  the  ethmoidal  sinuses;  7,  points  to  the  posi- 
tion of  the  ethmoidal  foramina;  8,  nasal  spine;  9, 
thick  rough  border  articulating  with  the  great  wing 
of  the  sphenoid  bone;  10,  refers  to  the  black  spot 
which  indicates  the  position  of  a  fossa  for  the 
trochlea  of  the  superior  oblique  muscle;  to  its 
outer  side  is  the  supra-orbital  notch ;  11,  internal 
angular  process,  and  entrance  to  the  frontal  sinus; 
12,  external  angular  process. 


1  Crista  frontalis. 

2  Foramen  coecum. 

3  Porus  cranio-nasalis. 

4  Paries  orbitales  or  horizontales. 


5  Incissura  ethmoidalis. 

6  Fovea  glandulae  lachrymal! 

7  Foveola  trochlearis. 


60 


THE   SKELETON. 


front/al  si'nus.1  This  cavity  extends  upward  and  outward  within  the 
position  of  the  superciliary  ridge,  and  varies  in  size  in  different  individ- 
uals. Very  rarely  it  does  not  exist ;  but  not  unfrequently  it  extends  as 
high  as  the  frontal  prominence,  and  backward  into  the  orbital  plate. 
It  is  separated  from  the  other  by  a  partition,  and  communicates  through 
the  anterior  ethmoidal  sinuses  with  the  nose. 

The  upper  thick  dentated  border2  articulates  with  the  parietal  bones, 
and  the  lateral  beveled  and  roughened  border  with  the  sphenoid  bone. 

THE  PARIETAL  BONE. 

The  Pari'etal  bone3  forms  the  upper  part  of  the  cranial  vault  between 
the  frontal  and  occipital  bones,  and  is  united  with  its  fellow  in  the 
median  line.  It  is  square,  with  the  external  surface  convex  and  smooth, 


FIG.  37. 


FIG. 


OUTER  VIEW  OF  THE  LEFT  PARIETAL  BONE.  1, 
upper  border;  2,  beveled  lower  border,  which  ar- 
ticulates with  the  squamous  portion  of  the  tempo- 
ral bone;  3,  anterior  border,  joining  the  frontal 
bone;  4,  occipital  border;  5,  temporal  ridge;  (, 
venous  foramen;  7,  prolonged  anterior  inferior 
angle  joining  the  summit  of  the  great  wing  of  the 
sphenoid  bone ;  8,  posterior  inferior  angle  articu- 
lating with  the  mastoid  portion  of  the  temporal 
bone. 


INNER  VIEW  OF  THE  LEFT  PARIETAL  BONE.  1-4, 
borders  corresponding  with  same  numbers  in  for- 
mer figure;  5,  groove  for  the  longitudinal  sinus, 
and  communication  with  it,  of  a  venous  foramen, 
6;  7,  8,  anterior  and  posterior  inferior  angles;  the 
groove  on  the  latter  accommodates  the  lateral 
sinus.  The  arborescent  lines  on  the  inner  concave 
surface  of  the  bone  indicate  grooves  produced  by  the 
great  meningeal  artery. 


and  the  internal  surface  concave,  ridged,  and  impressed  by  the  aborescent 
branches  of  the  great  meningeal  artery. 

Toward  the  middle  of  the  bone  externally  is  the  most  prominent  part, 
named  the  pari'etal  eminence  ;*  and  just  below  this  is  a  superficial  curved 


1  S.  superciliaris;  s.  pituitarii  front  is; 
caverna  frontis. 

2  Margo  coronalis. 

3  Os  parietale  ;    o.    bregmaticum  ;    o. 


verticale;  o.  verticis;  o.  tetragonum  ;  o. 
nervale. 

4  Tuber  parietale;   parietal  protuber- 
ance. 


THE   SKELETON. 


61 


line,  the  tem/poral  ridge,  which  defines  the  upper  part  of  the  temporal 
fossa. 

Along  the  superior  border  internally,  of  the  two  bones  in  conjunction,  a 
shallow  groove  is  visible,  indicating  the  course  of  the  longitudinal  sinus. 

Of  the  four  angles  of  the  parietal  bone,  the  anterior  inferior  is  most 
prolonged,  and  articulates  with  the  great  wing  of  the  sphenoid  bone. 

The  posterior  inferior  angle  joins  the  mastoid  portion  of  the  temporal 
bone,  and  internally  is  impressed  by  the  lateral  sinus. 

Of  the  four  borders  of  the  bone,  the  anterior,  superior,  and  posterior 
are  nearly  straight,  thick,  and  dentated  for  articulation  with  the  frontal, 
the  opposite  parietal,  and  the  occipital  bones.  The  inferior  border  is 
curved  and  beveled  to  a  sharp  edge  for  articulation  with  squamous  por- 
tion of  the  temporal  bone. 


THE  TEMPORAL  BONE. 


The  Tem/poral  bone1 

extends  into  its  base. 
It  is  of  complex  form, 
and  divisible  into  the 
squamous,  mastoid,  and 
petrous  portions. 

The  squa'mous  por- 
tion,2 so  named  from  its 
scale-like  form,  presents 
an  external  smooth  sur- 
face, which  contributes 
to  the  temporal  fossa; 
and  an  internal  surface, 
marked  by  the  cerebral 
convolutions  and  great 
meningeal  artery,  form- 
ing part  of  the  middle 
cerebral  fossa.  Its  up- 
per border  is  beveled 
to  a  thin  edge,  and  over- 
laps the  contiguous  bor- 
der of  the  parietal  bone ; 
and  its  anterior  border, 
less  beveled,  articulates 


is  situated   at   the  side  of  the   cranium,  and 
FIG.  39. 


EXTERNAL  VIEW  OP  THE  TEMPORAL  BONE  OP  THE  RIGHT  SIDE.  1, 
squamous  portion;  2,  mastoid  portion;  3,  apex  of  the  petrous  por- 
tion; 4.  zygomatic  process;  5,  glenoid  cavity;  6,  glenoid  tubercle 
7,  glenoid  fissure;  8,  mastoid  process;  9,  back  part  of  digastric 
groove;  10,  mastoid  foramen;  11,  auditory  process,  by  extension 
inwardly,  forming  the  vaginal  process ;  12,  external  auditory  meatus ; 
13,  styloid  process;  14,  slight  impression  of  the  deep  temporal 
artery. 

with  the   sphenoid   bone.      From   near  the 


1  Os  temporale  ;  o.  temporis  ;  o.  parietale  inferius;  o.  lapidosum  ;  o.  squamosum ; 
o.  crotaphy ticum ;  o.  memento  mori ;  o.  mendosum;  o.  arcuale;  o.  armale. 

2  Pars  squaitiosa ;  squama;  lepisma;  os  lepidoides;  os  squamiforme. 


62 


THE   SKELETON. 


FIG.  40. 


middle  of  its  lower  border  externally,  the  zygomat'ic  process1  arches 
outward  and  forward  to  join  the  corresponding  process  of  the  malar 
bone,  and  thus  form  the  zygo'ma2  or  yoke  through  which  the  tem- 
poral muscle  proceeds  to  its  insertion.  Beneath  and  internal  to 
the  position  of  the  root  of  the  process,  is  a  transverse  concavity,  the 
gle'noid  fossa,3  and  in  advance  of  this  a  transverse  eminence,  the  gle'- 

noid  tubercle,4  both  of 
which  enter  into  the  artic- 
ulation of  the  lower  jaw. 
Posteriorly,  the  fossa  is 
separated  from  the  pet- 
rous portion  of  the  bone 
by  the  gle'noid  fissure,5 

The  mas'toid  portion,6 
named  from  its  nipple-like 
prominence,  occupies  the 
back  part  of  the  bone,  and 
articulates  with  the  pari- 
etal and  occipital  bones. 
It  is  thick,  and  occupied 
interiorly  with  the  mas'- 
toid  sinuses,7  which  com- 
municate with  the  tym- 
panum. The  flattened  nip- 
ple-shaped prominence,  or 
mas'toid  process,8  pro- 
jects downward,  and  is 
roughened  for  muscular 
attachment.  On  its  inner 
side  is  situated  the  di- 
gas'tric  groove,9  for  the 
origin  of  the  correspon- 
sively  named  muscle. 


INTERNAL  VIEW  OF  THE  TEMPORAL  BONE  OF  THE  LEFT  SIDE. 
1,  squamous  portion ;  2,  posterior  border  of  the  mastoid  portion 
articulating  with  the  occipital  bone ;  3,  petrous  portion ;  \4,  bev- 
eled edge,  which  overlaps  the  lower  edge  of  the  parietal  bone ; 
5,  thick  upper  border  of  the  mastoid  portion,  articulating  with 
the  posterior  inferior  angle  of  the  parietal  bone;  6,  end  of  the 
zygomatic  process;  7,  groove  produced  by  the  great  meningeal 
artery;  8,  mastoid  process;  9,  digastric  groove;  10,  mastoid 
foramen  opening  into  the  groove  11,  for  the  lateral  sinus ;  12,  in- 
ternal auditory  meatus;  13,  styloid  process;  14,  prominence 
produced  by  one  of  the  semicircular  canals  of  the  labyrinth  ; 
15,  Fallopian  hiatus;  16,  foramen  for  the  transmission  of  a 
branch  of  the  tympanic  nerve ;  17,  cleft  which  transmits  a  small 
blood-vessel  to  the  vestibule  of  the  labyrinth;  18,  termination 
of  the  carotid  canal;  19,  Eustachian  tube;  20,  groove  of  the 
euperior  petrosal  sinus.  The  inner  surface 

mastoid  portion  forms  part  of  the  cerebellar  fossa,  and  presents  a  wide 


1  Processus  zygomaticus;  p.  jugalis. 

2  Arcus  zygomaticus;  zygomatic  arch. 

3  Fossa  glenoidalis. 

4  Tuberculum  articulare. 

5  Fissura  Glasseri ;  Glasserian  fissure. 

6  Pars  mastoidea;  p.  mammillaris. 


7  Cellulae     mastoideae ;    antrum    mas- 
toideum. 

8  Processus     mastoideus ;     apophysis 
mammillaris. 

9  Digastric  fossa;  mastoid  groove;  in- 
cissura  mastoidea. 


THE   SKELETON.  63 

descending  groove,1  which  indicates  the  course  of  the  lateral  sinus.  From 
the  groove  a  foramen2  generally  perforates  the  border  of  the  bone  for 
the  transmission  of  a  vein  from  the  scalp. 

The  petrous  portion,3  named  from  its  comparative  hardness,  contains 
the  labyrinth  and  tympanum.4  It  forms  a  prostrate,  trilateral  pyramid 
projecting  into  the  base  of  the  cranium  inward  and  forward.  Its  base 
rests  against  the  junction  of  the  other  two  portions  of  the  bone,  and 
between  these,  externally,  presents  the  external  auditory  mea'tus,5 
a  wide  oval  canal,  directed  inward  and  forward  to  the  tympanum,  and 
bounded  below  by  a  scroll-like  plate,  the  auditory  process,  the  border 
of  which  is  rough,  for  the  attachment  of  the  auricle.  The  apex  of  the 
petrous  portion  is  received  in  the  interval  between  the  spinous  process  of 
the  sphenoid  bone  and  the  anterior  part  of  the  occipital  bone. 

Of  the  three  surfaces  of  the  petrous  portion,  the  anterior  forms  part 
of  the  middle  cerebral  fossa;  the  posterior  forms  part  of  the  cerebellar 
fossa ;  and  the  inferior  surface  is  directed  downward. 

The  anterior  surface  is  an  inclined  plane  with  its  inner  end  impressed 
by  the  semilunar  ganglion  of  the  trifacial  nerve,  and  its  upper  part  ren- 
dered prominent  by  one  of  the  semicircular  canals  of  the  labyrinth.  Its 
inner  third  presents  an  inconspicuous  narrow  groove,6  leading  outwardly 
to  a  small  foramen,7  which  communicates  with  the  Fallopian  canal,  and 
transmits  a  branch  of  the  pterygoid  nerve.  Below  the  groove  are 
one  or  two  smaller  foramina,8  likewise  intended  for  the  transmission  of 
nerves. 

The  posterior  surface  also  forms  an  inclined  plane.  At  its  inner  third 
is  an  oblique  canal  directed  outwardly,  the  internal  auditory  mea'tus,9 
which  transmits  the  auditory  and  facial  nerve.  The  bottom10  of  the 
meatus  is  divided  by  a  transverse  ridge  into  two  pits,  in  the  upper 
one  of  which  commences  the  Fallo'pian  canal,11  for  the  further  passage 
of  the  facial  nerve.  The  canal  is  at  first  directed  forward,  and  then 
turns  abruptly  backward  and  outward  at  the  upper  part  of  the  tym- 
panum, and  subsequently  descends  to  the  stylo-mastoid  foramen.  The 


1  Sulcus  sinus  transversi ;    fossa  sig-  7  Fallopian   hiatus ;    hiatus   Fallopii ; 
moidea.  hiatus  canalis  Fallopiae ;  foramen  Vidi- 

2  F.  mastoideum.  ani;    apertura   spuria;   for.  Tarini;    f. 

3  Pars  petrosa  ;  pars  pyramidalis ;  pe-  anonymum  Ferreinii. 
trous  process  ;  os  lapideum;    o.  durum;  8  Canaliculi  petrosi. 

o.  lithoides;  o.  saxeum;  o.  petrosum ;  o.  9  Meatus  auditorius  internus;    porus 

praeruptae  rupi  assimilatum;  o.  nervale.  or  sinus  acusticus  int. 

4  See  Organ  of  Hearing.  ™  Macula  cribrosa. 

5  Meatus  auditorius  externus.  n  Canalis  Fallopiae;  aqueductus  Fal- 

6  Semicanalis  nervi  Vidiani.  lopise  ;  can.  facialis. 


64 


THE   SKELETON. 


FIG.  41. 


other  portions  of  the  bottom  of  the  internal  auditory  meatus  transmit 
the  divisions  of  the  auditory  nerve  to  the  labyrinth,  in  a  manner 
more  particularly  described  hereafter.1  About 
the  fourth  of  an  inch  external  to  the  entrance 
of  the  meatus  there  is  a  short  cleft,  which 
communicates  with  a  small  foramen2  for  the 
transmission  of  a  vein  from  the  vestibule  of 
the  labyrinth.  At  the  upper  border  of  this 
surface  is  a  groove3  for  conducting  the  superior 
petrosal  sinus  to  the  lateral  sinus. 

The  inferior  surface  of  the  petrous  portion  of 
the  bone  presents  many  points  of  interest.  At 
its  anterior  outer  part  is  the  plate  of  bone 
which  forms  the  aud'itory  proc'ess,4  defined 
above  by  the  glenoid  fissure,  and  below  by  a 
sharp  crest  named  the  vag'inal  process,5  which 
partly  ensheathes  the  base  of  the  sty'loid  proc- 
ess.6 The  latter  is  a  tapering  spine,  of  variable 
length,  projecting  downward,  forward,  and  in- 
ward, and  connected  to  the  hyoid  bone  by  means 
of  a  round,  fibrous  cord,  the  stylo-hy'oid  lig'a- 
ment. 

Between  the  styloid  and  mastoid  processes 
is  the  sty'lo-mas'toid  fora'men,7  which  is  the 
termination  of  the  Fallopian  canal,  and  gives 
exit  to  the  facial  nerve. 

Behind  the  styloid  process  is  a  surface  tipped 
with  cartilage,  the  artic'ular  process,  which 
joins  the  transverse  process  of  the  occipital 
bone.  To  the  inner  side  of  this  surface  is  a 
concave  depression,  the  ju/gular  fos'sa,8  in 
which  the  internal  jugular  vein  commences. 
To  the  inner  side  of  the  fossa  is  a  notch, 
part  of  the  jugular  foramen,  containing  a 
three-sided  pit,  at  the  bottom  of  which  is  a 
foramen9  for  the  transmission  of  a  vein  from  the  cochlea  of  the  labyrinth. 


INFERIOR  VIEW  OP  THE  LEFT 
TEMPORAL  BONE.  1,  squamous  por- ' 
tiou;  2,  mastoid  portion;  3,  pe- 
trous portion ;  4,  border  articulat- 
ing with  the  great  wing  of  the 
sphenoid  bone ;  5,  zygomatic  proc- 
ess; 6,  glenoid  cavity;  7,  glenoid 
tubercle;  8,  glenoid  fissure;  9, ex- 
ternal auditory  meatus;  10,  mas- 
toid process;  11,  digastric  groove; 
12,  styloid  process;  13,  stylo-mas- 
toid  foramen;  14,  jugular  fossa; 

15,  pit  which    transmits  a  vein 
from  the  cochlea  of  the  vestibule; 

16,  position  between  which  and 
the    occipital    bone     the    ninth, 
tenth,  and  eleventh  cerebral  nerves 
escape    from    the    cavity  of  the 
cranium;   17,  articular   process; 
18,  vaginal  process;   19,  20,  en- 
trance and  exit  of  the  carotid  ca- 
nal;   21,  Eustachian     tube;    22, 
mastoid  foramen. 


1  See  Organ  of  Hearing. 

2  Aqueductus  vestibuli. 

3  Sulcus  petrosus  superior. 

4  Processus  auditorius. 

5  Processus  vaginalis. 


6  P.  styloideus. 

7  F.  stylo-mastoideum. 

8  Fossa  jugularis ;  thimble-like  cavity. 

9  Aqueductus  cochleae. 


THE   SKELETON.  65 

Below  the  notch  is  the  entrance  of  the  carot/id  canal,1  which  ascends 
and  then  turns  at  a  right  angle  forward  and  inward  to  the  apex  of  the 
petrous  portion  of  the  bone,  and  transmits  the  internal  carotid  artery 
to  the  cavity  of  the  cranium. 

In  the  crest,  which  separates  the  jugular  fossa  and  carotid  canal,  is  a 
small  foramen,2  which  transmits  the  tympanic  branch  of  the  glosso- 
pharyngeal  nerve  to  the  tympanum. 

The  anterior  border  of  the  petrous  portion,  in  the  notch  separating  it 
from  the  squamous  portion,  exhibits  the  irregular  orifice  of  a  canal,  which 
communicates  with  the  tympanum  and  is  divided  into  two  parts  by  a  par- 
tition.3 The  upper  division4  of  the  canal  accommodates  the  tensor 
muscle  of  the  tympanum,  and  the  lower  one  forms  part  of  the  Eusta'- 
chian  tube.5 

STRUCTURE  AND  ARTICULATION   OF  THE  BONES  OF  THE 

CRANIUM. 

The  bones  of  the  cranium,  excepting  when  they  are  especially  thin,  as 
in  the  case  of  the  ethmoid  bone,  the  orbital  plates  of  the  frontal  bone, 
the  squamous  portion  of  the  temporal  bone,  and  the  cerebellar  fossae  of 
the  occipital  bone,  are  composed,  as  in  the  case  of  tabular  bones  gener- 
ally, of  two  layers  of  compact  substance,  with  an  intervening  spongy  sub- 
stance.6 The  outer  table  of  compact  substance  is  much  more  tenacious 
than  the  inner  one,  which  from  its  comparative  brittleness  has  received 
the  name  of  the  vitreous  table.  The  spongy  substance  varies  in  the 
extent  of  its  development  in  different  individuals  and  races ;  and  gener- 
ally it  is  more  abundant  in  the  negro  than  in  the  white  race. 

The  bones  of  the  cranium  are  nearly  all  united  by  suture.  Before 
puberty,  the  basilar  process  of  the  occipital  bone  articulates  with  the 
body  of  the  sphenoid  bone,  by  means  of  fibro-cartilage,  which  speedily 
ossifying,  unites  the  two  bones  into  one  piece.  The  transverse  process 
of  the  occipital  bone  is  connected  with  the  articular  process  of  the 
temporal  bone  by  cartilage,  which  likewise  speedily  ossifies.  The 
anterior  border  of  the  petrous  portion  of  the  temporal  bone  is  simply 
coadapted  with  the  posterior  border  of  the  great  wing  of  the  sphenoid 
bone ;  but  its  apex  and  posterior  border,  as  far  as  the  jugular  foramen, 
are  united  with  the  contiguous  borders  of  the  sphenoid  and  occipital 

1  Canalis  caroticus.  *  Semicanalis  tensoris  tympani. 

2  Canaliculus  tympanicus.  5  Bony  portion  of  the  Eustachian  tube. 

3  Processus  cochlearifonnis.  6  Dipke ;  diploic  structure, 


66  THE   SKELETON. 

bones,  by  fibro-cartilage,  which  ordinarily  remains  to  a  late  period  of 
life. 

In  all  other  instances,  the  cranial  bones  are  united  by  suture,  generally 
of  the  dentated  or  serrated  variety,  in  which  the  contiguous  borders  of 
the  bones  are  jagged,  and  mutually  knit  together  in  such  a  manner  as 
frequently  to  require  considerable  force  to  separate  them.  The  remaining 
sutures  are  of  the  squamous,  or  scale-like  variety,  in  which  the  contigu- 
ous borders  of  the  bones  are  beveled  off,  roughened,  and  mutually 
coadapted. 

The  bones  of  the  cranium  are,  however,  not  merely  conjoined  by 
suture — th#y  are  actually  continuous  through  intervening  cartilage ;  for 
if  an  unmacerated  cranium  be  treated  with  muriatic  acid,  so  as  to  remove 
the  calcareous  salts,  the  sutures  disappear,  and  the  cranium  remains 
as  a  flexible  case  of  bone-cartilage. 

The  principal  sutures  of  the  cranium  are  the  fronto-parietal,1  the 
inter-parietal,2  the  occipito-parietal,3  and  occipito-temporal,4  which  are 
of  the  dentated  or  serrated  variety;  and  the  temper o-parietal,5  and 
spheno-parietal,  which  are  of  the  squamous  variety.  The  spheno-tem- 
poral,  spheno-frontal,  and  fronto-ethmoida!  partake  of  both  the  den- 
tated and  squamous  character. 

The  sutures  of  the  cranial  vault  are  remarkable  for  their  exceedingly 
intricate  and  winding  course,  which  has  always  rendered  them  one  of  the 
most  striking  characters  in  the  anatomy  of  the  skull.  This  intricacy  is, 
however,  confined  to  the  exterior  of  the  cranium,  for  it  extends  only 
through  the  outer  layer  of  compact  substance  of  the  bones.  In  the 
interior  of  the  cranium  the  same  sutures  present  a  merely  waving,  or 
slightly  tortuous  course. 

In  early  life,  the  sutures  are  less  intricate  than  later ;  and  after  the 
brain  has  reached  its  full  development  and  growth,  they  gradually 
become  more  or  less  completely  obliterated  by  the  ossification  of  the 
intervening  cartilage.  This  obliteration  usually  commences  with  the 
occipito-temporal  suture,  then  occurs  with  the  inter-parietal,  then  the 
fronto-parietal,  and  afterwards  the  occipito-parietal  suture. 

Occasionally  the   inter-parietal    suture   ossifies   at   a  comparatively 

1  Coronal  suture ;  sutura  coronalis ;  5  Squamous  suture  ;  s.  squamosa ;  s. 

s  arcualis.  mendosa ;  s.  lepidoides.  The  part  of  the 

2Sagital  suture;  sutura  biparietalis ;  suture  which  is  not  squamous  and  unites 

8.  virgata ;  s.  rhabdoides;  s.  jugalis.  the  parietal  bone  with  the  mastoid  por- 

3  Lambdoidal  suture;  s.  lambdoidalis ;  tion  of  the  temporal  bone  is  the  addita- 
s.  occipitalis.  mentum  suturce  squamosse. 

4  Additamentum  suturje  lambdoidalis. 


THE   SKELETON.  tfj 

early  period,  when,  in  consequence  of  the  subsequent  growth  of  the 
brain  being  less  retarded  antero-posteriorly,  the  cranium  becomes  more 
elongated  than  usual. 

The  frontal  bone  at  birth  consists  of  two  distinct  pieces  united  in  the 
median  line.  The  two  pieces  usually  co-ossify  before  the  third  year  of 
infantile  life,  but  occasionally  remain  connected  by  serrated  suture. 
In  such  cases  the  front'al  suture  is  apt  to  be  among  the  most  perma- 
nent. 

GENERAL  CONFORMATION  OF  THE  CRANIUM.  ' 

The  Cra'nium1  is  egg-shaped  or  ovate ;  the  long  diameter  being 
antero-posterior,  and  the  narrow  extremity  forward.  It  is  moulded 
upon  its  contents,  so  that  its  interior  surface  presents  impressions  cor- 
responding with  the  form  of  the  brain,  and  grooves  corresponding  with 
the  sinuses  and  arteries  of  the  dura  mater.  Its  exterior,  however,  is  not 
the  exact  counterpart  of  the  interior,  so  that  even  if  the  different  facul- 
ties of  the  brain  were  localized,  as  pretended  by  phrenologists,  they 
could  not  be  accurately  determined  by  an  examination  of  the  cranium. 
Most  of  the  perceptive  faculties  indeed  would  have  nothing  to  do  with 
the  brain,  if  they  were  situated,  as  phrenologists  have  placed  them,  over 
the  position  of  the  vacant  spaces  constituting  the  frontal  sinuses. 

The  interior  surface  of  the  vault  or  top  of  the  cranium  is  marked  by 
the  cerebral  convolutions.  Along  its  median  line  may  be  observed  the 
shallow  groove  impressed  by  the  course  of  the  longitudinal  sinus.  On 
each  side  of  the  position  of  this  groove,  more  especially  on  the  parietal 
bones,  irregular  depressions,  resembling  ulcerations,  are  not  unfrequently 
observable.  These  are  the  result  of  absorption  from  the  pressure  of 
certain  anomalous  deposits  of  the  membranes  of  the  brain,  called  Pac- 
chionian  bodies. 

The  bottom  of  the  cavity  of  the  cranium  presents  three  pairs  of  well- 
marked  fossae.  The  anterior  cranial  fossae2  accommodate  the  anterior 
cerebral  lobes,  and  correspond  with  the  roofs  of  the  orbits.  They  are 
formed  by  the  orbital  plates  of  the  frontal  bone,  strongly  marked  by 
cerebral  convolutions,  and  the  small  wings  of  the  sphenoid  bone,  which 
constitute  their  posterior  boundary.  Between  them  projects  the  eth- 
moidal  crest,  separating  on  each  side  the  ethmoidal  gutters,  for  the  lodg- 
ment of  the  olfactory  bulbs. 

1  The  cranium  proper;  the  brain  pan  ;  2  Fosses  anteriores  basis  cranii ;  f.  ce- 

brain   case ;    cranion ;    scaphion ;    con-      rebrales  anteriores. 
chus ;  theca  cerebri ;  ollacapitis. 


68 


THE  SKELETON. 


The  middle  cranial  fossae,1 
FIG.  42. 


INTERNAL  VIEW  OF  THE  BASE  OF  THE 
CRANIUM  OF  THE  LEFT  SIDE,  a,  I,  c,  an- 
terior, middle,  and  posterior  cranial  fossae ; 
1,  orbital  plate  of  the  frontal  bone;  2,  small 
wing  of  the  sphenoid  bone;  3,  great  wing 
of  the  same;  4,  squamous  portion  of  the 
temporal  bone ;  5,  petrous  portion  of  the 
same ;  6,  inastoid  portion ;  7,  parietal  bone; 
8,  occipital  bone;  9,  ethmoidal  gutter  and 
ethmoidal  crest;  10,  pituitary  fossa ;  11,  an- 
terior clinoid  process ;  12,  declivity ;  13,  oc- 
cipital foramen ;  14,  optic  foramen ;  15,  ro- 
tund foramen ;  16,  oval  foramen ;  17,  spin- 
ous  foramen  and  groove  from  it,  indicating 
the  course  of  the  great  meningeal  artery; 
18,  lacerated  foramen  19,  internal  audit- 
ory meatus ;  20,  jugular  foramen;  21,  con- 
dyloid  foramen ;  22,  commencement  of  the 
groove  for  the  lateral  sinus.  The  course  of 
the  groove  is  observed  along  the  horizontal 
limb  of  the  occipital  crest,  the  posterior 
inferior  angle  of  the  parietal  bone,  the 
mastoid  portion  of  the  temporal  bone,  and 
the  transverse  process  of  the  occipital 
bone,  terminating  at  the  jugular  foramen. 


which  receive  the  middle  cerebral  lobes, 
are  formed  by  the  great  wings  of  the  sphe- 
noid bone,  the  squamous  portions  of  the 
temporal  bones,  and  the  anterior  surfaces 
of  the  petrous  portions  of  the  latter.  Their 
anterior  boundary  is  the  sharp  crescentric 
border  of  the  small  wings  of  the  sphenoid 
bone,  and  their  posterior  boundary  the 
upper  border  of  the  petrous  portion  of 
the  temporal  bones.  They  intercommuni- 
cate through  the  pituitary  fossa. 

Between  the  apex  of  the  petrous  por- 
tion of  the  temporal  bone  and  the  body 
and  great  wing  of  the  sphenoid  bone, 
there  is  a  large  irregular  aperture,  the 
lacerated  fora'men,2  which  is  closed  be- 
low by  a  thin  plate  of  cartilage,  but  is 
occupied  at  the  upper  part  of  its  area  by 
the  internal  carotid  artery,  as  it  proceeds 
from  the  carotid  canal  to  the  side  of  the 
body  of  the  sphenoid  bone. 

From  the  spinous  foramen,  the  groove 
for  the  middle  meningeal  artery  ascends 
a  short  distance  near  the  anterior  border 
of  the  squamous  portion  of  the  tem- 
poral bone,  when  it  divides  into  two 
branches.  One  of  these  continues  along 
the  squamous  portion  of  the  bone  to  its 
back  part,  when  it  mounts  upon  the  parietal 
bone,  subdividing  in  numerous  branchlets. 
The  other  branch  turns  over  the  summit 
of  the  great  wing  of  the  sphenoid  bone, 
and  then,  like  the  preceding,  ascends  on 
the  parietal  bone. 

The  posterior  cranial  fossae,3  more 
capacious  than  the  others,  receive  the 
lobes  of  the  cerebellum.  They  are  formed 
by  the  posterior  surfaces  of  the  petrous 
portions  of  the  temporal  bones,  the  mas- 
toid portions  of  the  latter,  and  the  occip- 


1  F.  med.  basis  cranii ;  f.  cereb.  med.        2  Foramen  lacerum  ;  f.  lacerum  medius. 
3  F.  post,  basis  cranii;  f.  cerebelli. 


THE   SKELETON.  69 

ital  bone  below  the  lateral  limbs  of  the  occipital  cross.  They  are  sepa- 
rated posteriorly  by  the  vertical  limb  of  the  latter,  and  anteriorly  com- 
municate through  the  inclined  surface  of  the  declivity  of  the  sphenoid 
bone  and  the  basilar  process,  upon  which  rest  the  medulla  oblongata  and 
the  pons. 

From  the  groove  for  the  longitudinal  sinus,  that  for  the  lateral  sinus 
may  be  seen  following  the  course  of  the  horizontal  limb  of  the  occipital 
cross,  then  curving  down  upon  the  mastoid  portion  of  the  temporal  bone, 
and  over  the  transverse  process  of  the  occipital  bone  to  the  jugular  fora- 
men. Usually  the  groove  upon  the  right  side  is  larger  than  that  upon 
the  left. 

The  ju/gular  fora'men1  is  an  irregular  orifice  formed  by  the  con- 
tiguity of  two  notches  between  the  petrous  portion  of  the  temporal 
bone  and  the  occipital  bone.  It  is  usually  more  or  less  subdivided  by  a 
short  process  projecting  from  near  the  middle  of  the  notch  of  the  petrous 
portion  of  the  temporal  bone.  The  outer  and  larger  division  admits  of 
the  termination  of  the  lateral  sinus  in  the  internal  jugular  vein,  and  the 
inner  division  transmits  the  ninth,  tenth,  and  eleventh  cranial  nerves. 
In  accordance  with  the  usually  larger  size  of  the  right  lateral  sinus  than 
the  left  one,  the  right  jugular  foramen  and  the  right  internal  jugular 
vein  are  also  larger  than  those  of  the  left  side. 

The  external  surface  of  the  vault  of  the  cranium,2  covered  by  the 
scalp,  is  smooth ;  and  its  front  forms  the  forehead,  its  back  the  occiput, 
and  its  sides  contribute  to  the  temporal  fossae.3  The  latter  give  origin 
to  the  temporal  muscles,  and  are  defined  above  by  a  superficial  ridge 
or  line  commencing  at  the  external  angular  process  of  the  frontal  bone, 
and  arching  upward  and  backward  upon  the  parietal  bone  to  the  divid- 
ing line  between  the  squamous  and  petrous  portions  of  the  temporal 
bone.  Inferiorly  the  temporal  fossa  is  defined  by  a  ridge  proceeding 
inward  and  forward  from  the  root  of  the  zygomatic  process  of  the  tem- 
poral bone,  and  becoming  continuous  with  another  dividing  the  external 
surface  of  the  great  wing  of  the  sphenoid  bone  into  two  parts. 

The  exterior  of  the  base  of  the  cranium  is  exceedingly  irregular. 
Transverse  lines  directed  from  external  conspicuous  points  would  indi- 
cate important  parts  as  follows  : — 

1.  A  line  between  the  ends  of  the  mastoid  processes  would  pass 
nearly  through  the  middle  of  the  occipital  foramen. 

2.  A  line  between  the  external  auditory  meatuses  would  pass  through 
the  jugular  foramina  and  the  anterior   part  of  the  occipital  foramen 
and  condyles. 

1  F.  jugulare  ;  f.  lacerutn  posterius.  2  Skull  cap ;  calvaria  ;  calva;  camera. 

3  Fossae  temporales. 


70 


THE   SKELETON. 


3.  A  line  between  the  glenoid  cavities  would  pass  through  the  entrance 
of  the  carotid  canals. 

4.  A  line  between  the  glenoid  tubercles  would  pass  through  the  exit 

of  the  carotid  canals 
and  the  lacerated  fora- 
mina. 

5.  A  line  between  the 
middle  of  the  zygomat- 
ic  processes  of  the  tem- 
poral bones  would  pass 
through  the  roots  of 
the  pterygoid  processes 
which  separate  the  oval 
foramina  and  the  pos> 
terior  nares. 

The  occipital  con- 
dyles,  by  which  the 
skull  is  supported  on 
the  vertebral  column, 
are  placed  posterior  to 
the  middle  line  of  the 
cranium. 

The  posterior  ob- 
lique border  of  the 
great  wing  of  the  sphen- 
oid bone  forms,  with 
the  contiguous  border 
of  the  petrous  portion 
of  the  temporal  bone, 

a  groove  which  accommodates  the  inferior  portion  of  the  Eustachiau 

tube. 


FlG.  43.  EXTERNAL  VIEW  OF  THE  BASE  OF 

THE  SKULL,  RIGHT  SIDE.     1,  palate 

plate  of  the  superior  maxillary 
bone ;  2,  palate  plate  of  the  pal- 
ate bone;  3,  vomer;  4,  5,  internal 
and  external  pterygoid  processes; 
6,  pyramidal  process  of  the  palate 
bone ;  5,  6,  occupy  the  pterygoid 
fossa ;  7,  under  part  of  the  great 
wing  of  the  sphenoid  bone,  form- 
ing part  of  the  spheno-maxillary 
fossa ;  8,  temporal  surface  of  the 
great  wing  of  the  sphenoid  bone ; 
9,  zygoma;  10,  zygomatic  process 
of  the  malar  bone ;  11,  zygomatic 
process  of  the  temporal  bone;  12, 
squamous  portion  of  the  temporal 
bone;  13,  glenoid  tubercle;  14, 
glenoid  fossa;  15,  auditory  and 
vaginal  process ;  16,  styloid  proc- 
ess; 17,  external  auditory  mea- 
tus ;  18,  mastoid  process ;  19,  di- 
gastric fossa;  20,  conjunction  of 
the  basilar  process  and  body  of 
the  sphenoid  bone ;  21,  occipital 
condyle;  22,  occipital  protuber- 
ance, and  crest  leading  from  it 
downward;  23,  24,  superior  and 
inferior  semicircular  ridges;  25, 
occipital  foramen ;  26,  incisive  for- 
amen; 27,  posterior  palatine  for- 
amen ;  2S,  spheno-maxillary  fis- 
sure ;  29,  posterior  naris ;  30,  oval 
foramen  ;  31,  spinous  foramen ; 
32,  lacerated  foramen;  33,  Eustachian  tube;  34,  entrance  of  the 
carotid  canal;  35,  jugular  foramen ;  36,  stylo-mastoid  foramen;  37, 
pit  with  a  posterior  coudyloid  foramen ;  38,  mastoid  foramen. 


MECHANICAL  CONSTRUCTION  OF  THE  CRANIUM. 

A  sphere  is  best  adapted  to  resist  pressure  equally  applied  on  all 
sides,  and  therefore  of  all  abstract  forms  is  the  strongest.  It  or  its  modi- 
fications into  the  oval  and  ovate  forms  are  constantly  employed  in  the 
organic  kingdom  in  the  construction  and  protection  of  delicate  structures, 
as  instanced  in  the  organic  cell,  the  eggs  of  animals,  etc. 

Under  special  circumstances  the  oval  or  ovate  forms  are  better 
adapted  to  the  preservation  of  delicate  structures  than  the  perfect 
sphere. 


THE   SKELETON. 


71 


FIG.  44. 


The  human  cranium,  especially  adapted  to  the  protection  of  the  brain, 
is  ovate,  with  the  narrow  end  strongest  and  situated  forward,  where  it  is 
most  liable  to  violence. 

The  cranium  of  the  infant  varies,  from  the  more  mature  ovate  form,  in 
presenting  a  number  of  prominent  points  in  positions  liable  to  receive 
pressure  during  birth,  or  subsequently  to  receive  the  first  impression 
from  falls  or  blows. 

Prior  to  co-ossification  of  the  bones  of  the  cranium,  they  are  so  inti- 
mately and  admirably  articulated,  that  it  requires  considerable  force  to 
separate  any  one  of  them,  but  after  this  is  done  the  connection  of  the 
whole  becomes  more  or  less  enfeebled. 

The  sphenoid  bone  is  the  most  important  agent  of  connection  of  the 
bones  of  the  cranium ;  extending  transversely  across  the  base  of  the 
latter  it  articulates  with  all  the  other  bones  and  its  body  appears  to  be 
a  central  point  of  support  for  the  whole  of  them. 

If  sections  are  made  in  different  directions  through  the  cranium,  they 
will  exhibit  the  intimate  rela- 
tionship existing  in  the  con- 
nection of  the  bones  by  which 
so  many  pieces  are  enabled 
to  preserve  the  integrity  of 
the  cranium. 

Thus  a  vertical  antero-pos- 
terior  section  of  the  cranium 
exhibits  a  connection  of  its 
segments,  as  represented  in 
figure  44.  The  upper  border 
of  the  frontal  bone  rests  upon 

the    beveled    COntigUOUS  bor-          ANTERO-POSTERIOR  SECTION  OF  THE  CRANIUM,  exhibiting 

rlor.     ^f     fliA     T^ariofnl     hnnpc       the  mode  by  which  the  connection  of  the  different  bones  con- 

6S'      tributes  to  preserve  its  integrity.    1,  parietal  bone ;  2,  front- 

these  behind  abut  against  al  bone ;  3,  its  orbital  plate ;  4,  frontal  sinus ;  5,  body  of 
the  OCCipital  bone,  and  the  8Phenoid  bone'>  6>  sphenoidal  sinus;  7,  occipital  bone;  8, 

marginal  ridge  of  the  occipital  foramen. 

circle,  after  bifurcating   and 

surrounding  the  occipital  foramen,  terminates  in  the  basilar  process, 
which  is  firmly  supported  against  the  body  of  the  sphenoid  bone.  The 
latter  by  its  lesser  wings  affords  a  support  to  the  orbital  processes  of 
the  frontal  bone,  and  thus  the  circle  is  completed. 

A  horizontal  circle  of  the  cranium,  as  represented  in  figure  45,  exhibits 
the  borders  of  its  frontal  segment  overlapped  by  the  parietal  segments, 
and  these  likewise  slightly  overlapped  by  the  occipital  segment.  A 
circle  lower  down  will  exhibit  the  frontal  segment  overlapped  by  the 
great  wings  of  the  sphenoid  bone,  and  these  by  the  squamous  portions 


72 


THE   SKELETON. 


FIG.  45. 


of  the  temporal  bones,  which  likewise  behind  inclose  the  parietal  bones, 

also  slightly  overlapped  by 
the  occipital  bone. 

A  vertical  transverse  circle 
at  the  front  of  the  cranium, 
as  represented  in  figure  46, 
exhibits  a  frontal  arch  inter- 
locked by  the  sphenoid  bone. 
A  second  circle  a  short  dis- 
tance behind  the  preceding, 
as  represented  in  figure  4T, 
exhibits  the  parietal  bones 
dove-tailed  above,  and  in- 
terlocked by  the  sphenoid 
bone  below. 

A  third  circle  further  back, 
as  represented  in  figure  48, 
exhibits  the  parietal  bones 
articulating  as  in  the  pre- 
ceding instance,  and  interlocked  below  by  the  temporal  bones,  which 
abut  against  the  sphenoid  and  occipital  bones. 


HORIZONTAL  SECTION  OF  THE  CRANIUM.     1,  frontal  bone 
2,  parietal  bone ;  3,  occipital  bone. 


FIG.  46. 


FIG.  47. 


TRANSVERSE  SECTION  THROUGH  THE  FRONT  OF  THE 
CRANIUM.  1,  transverse  arch  formed  by  the  frontal 
bone ;  2,  great  wing  of  the  sphenoid  bone,  includ- 
ing or  overlapping  the  abutments  of  the  frontal 
arch ;  3,  body  of  the  sphenoid  bone,  with  its 
sinuses. 


TRANSVERSE  SECTION  IN  ADVANCE  OF  THE  MIDDLE 
OF  THE  CRANIUM.  1,  parietal  bone  forming  with 
its  fellow  an  arch ;  2,  great  wing  of  the  sphenoid 
bone ;  3,  horizontal  portion  of  the  wing ;  4,  body, 
with  the  sphenoidal  sinuses. 


A  fourth  circle  at  the  back  of  the  cranium,  as  represented  in  figure  49, 
exhibits  the  parietal  bones  joined  as  in  the  two  preceding  instances,  and 
fitting  into  a  notch  below,  between  the  squamous  and  mastoid  portions 
of  the  temporal  bones,  which,  as  before  stated,  abut  against  the  sphenoid 
and  occipital  bones. 


THE   SKELETON. 


73 


FIG.  48. 


FIG.  49. 


TRANSVERSE  SECTION  THROUGH  THE  MIDDLE  OP 
THE  CRANIUM.  1,  parietal  bone ;  2,  squamous  por- 
tion of  the  temporal  bone ;  3,  petrous  portion ;  4, 
body  of  the  sphenoid  bone. 


TRANSVERSE  SECTION  POSTERIOR  TO  THE  MIDDLE 
OP  THE  CRANIUM.  1,  back  part  of  the  parietal 
bones ;  2,  mastoid  portion  of  the  temporal  bone ; 
3,  mastoid  process  with  the  sinuses ;  4,  petrous  por- 
tion of  the  temporal ;  5,  sphenoidal  body,  or  the 
basilar  process  of.  the  occipital  bone. 


DEVELOPMENT  OF  THE  CRANIUM. 

The  occipital  bone  is  developed  from  seven  distinct  centres  of  ossifica- 
tion :  four  for  the  expanded  portion,  and  three  for  the  lower  portion. 
At  birth  it  consists  of  three  pieces :  the  upper  expanded  portion,1  the 
two  condyloid  portions,2  and  the  basilar  portion.3  They  usually  become 
united  into  one  piece  by  the  fifth  or  sixth  year. 

The  sphenoid  bone  is  developed  from  twelve  ossific  centres,  including 
the  formation  of  the  sphenoidal  sinuses  from  the  ethmoidal  pyramids. 
At  birth  it  consists  of  three  pieces :  the  body  and  small  wings  as  one, 
and  the  great  wing  and  pterygoid  processes  making  one  on  each  side. 
Subsequently,  during  the  first  year,  the  three  pieces  are  united  into 
one.  The  ethmoidal  pyramids  become  the  sphenoidal  sinuses  on  the 
approach  of  puberty. 

The  ethmoid  bone  is  developed  from  five  centres  of  ossification,  exclu- 
sive of  the  pyramids.  At  birth,  its  two  lateral  masses  only  are  ossi- 
fied, but  during  the  first  year  the  vertical  and  cribriform  plates  ossify 
and  become  united  with  the  former. 

The  frontal  bone  is  developed  from  two  ossific  centres,  which  corre- 
spond with  the  supra-orbital  ridges.  At  birth  it  consists  of  two  halves 
united  at  the  median  line.  They  usually  co-ossify  before  the  third 
year ;  but  occasionally  the  suture  remains  as  one  of  the  least  disposed 
to  obliteration. 


1  Supra-occipital   bone;     inter-parietal 
bone ;  squama  occipitalis. 


2  Exoccipitals ;  lateral  occipitals. 

3  Basioccipital   bone;    basilar    bone; 

inferior  occipital  bone. 


74  THE   SKELETON. 

The  parietal  bones  are  each  developed  from  a  single  centre  of  ossifica- 

tion, corresponding  with  the  parietal  protuberance. 

The  temporal  bones  are  each  developed  from  four  ossific  centres  :  one 

for  the  squamous  portion,  one  for  the  combined  petrous  and  mastoid 

portions,  one  for  the  auditory  process,  and  one  for  the  styloid  process. 

At  birth  it  usually  consists  of  three  pieces  :  the  squamous  portion  as  one, 
the  petrous  and  mastoid  portions  as  a  second, 
and  the  auditory  process  as  a  third,  which 
then  appears  as  a  ring  of  bone,  incomplete  at 
its  upper  part,  and  encircling  the  tympanic 
membrane.  The  three  pieces  speedily  unite 
after  birth,  and  the  ring  of  bone  encircling 
the  tympanic  membrane  gradually  elongates 
outward  into  the  external  auditory  meatus. 
The  styloid  process  subsequently  ossifies, 

TWO  PIECES  OF  THE  TEMPORAL  BONE,  .  .  ,  />        i  i  -i 

a*    observed    about    the    period    of    Vari6S      m     lts      degree     °f     development,     and 

birth;  the  third  piece  corresponding  sometimes    never  unites   with   the  temporal 

with   the  petrous  and  mastoid  por-    -, 

tions,  not  represented.    1,  the  squa- 

mous portion  of  the  temporal  bone;  The  tabular  bonCS  of   the  Vault  Of  the   Cl'a- 


t  the  Period  of  birth>  Present  the  aP- 

pearance  of  depressed  cones  ;  being  conspicu- 
ously prominent  at  their  centres,  which  correspond  with  the  frontal,  parietal, 
and  occipital  protuberances.  From  the  summits  of  the  cones  the  ossific 
structure  radiates  in  well-marked  lines  to  the  borders  of  the  bones,  which 
overlap  instead  of  interlocking  with  each  other,  as  they  do  subsequently. 
The  parietals  overlap  both  the  frontals  and  the  occipital.  From  this 
arrangement  of  the  vault  of  the  cranium,  compression  may  reduce  its 
diameters,  which  is  an  important  provision  in  the  passage  of  the  head  of 
the  child  through  the  pelvis  of  the  mother.  The  bones  at  the  base  of 
the  skull  meet  at  their  borders  without  overlapping  so  as  not  to  permit 
diminution  from  pressure,  which  is  not  only  unnecessary  from  the  small 
size  of  the  base  compared  with  the  vault,  but  which  would  prove  inju- 
rious to  the  parts  of  the  brain  concerned  in  this  position. 

At  or  near  the  period  of  birth,  there  are  several  membranous  spaces 
left  in  the  line  of  the  sutures,  through  which  ossification  has  not  extended, 
and  which  are  named  font/anels,1  The  largest  of  these  interspaces,  the 
anterior  font'anel,2  is  situated  at  the  contiguous  angles  of  the  two 
frontals  with  the  two  parietal  bones.  It  is  quadrangular,  with  the 
anterior  angle  much  prolonged  and  acute,  and  the  posterior  short  and 

1  Fontanellee  ;  fonticuli  ;  lacunae.  fons  pulsatilis  ;  vertex  palpitans  ;  fonti- 

2  Great,  sincipital,  or  frontal  fontanel  ;       culus  quadrangularis. 


THE   SKELETON.  75 

obtuse.  It  remains  unossified  for  several  months  after  birth;  and 
at  the  membranous  space,  the  pulsations  of  the  brain  may  be  felt.  The 
posterior  fonl/anel,1  situated  between  the  parietal  bones  behind,  is  usu- 
ally closed  at  birth  by  the  summit  of  the  occipital  bone. 

The  anterior  fontanel,  and  the  posterior  one,  or  the  three  sutures 
which  lead  to  its  position,  afford  important  means  to  the  midwife  in 
determining  the  relative  position  of  the  head  of  the  child  while  within 
the  pelvis  of  the  mother. 

At  the  sides  of  the  cranium  are  the  lateral  font'anels,  of  which  one 
is  situated  between  the  frontal,  temporal,  parietal,  and  sphenoid  bones,2 
and  the  other  is  placed  between  the  occipital,  temporal,  and  parietal 
bones.3 

The  bones  of  the  foetal  cranium  consist  of  a  single  layer  of  compact 
substance ;  the  spongy  substance  being  developed  in  them  subsequent  to 
birth.  The  frontal  and  mastoid  sinuses  are  developed  by  a  resolution  of 
the  spongy  substance. 

SUPERNUMERAKY  BONES  OF  THE  CRANIUM. 

Not  unfrequently  there  are  found  in  the  course  of  the  sutures  of  the 
cranium  supernumerary,  islet-like  bones,4  which  have  originated  frf>m 
distinct  centres  of  ossification.  They  rarely  occur  in  any  other  than 
the  sutures  of  the  vault  of  the  cranium,  and  of  these  are  most  frequent  in 
the  course  of  the  occipito-parietal  suture.  These  bones  vary  much  in 
number  and  size  ;  and  in  hydrocephalic  cases  are  often  numerous  and 
large.  Frequently  they  may  be  found  on  the  two  sides  of  the  cranium, 
alike  or  symmetrical  in  position.  Occasionally  one5  is  found  occupying 
the  former  position  of  the  anterior  fontanel. 

BONES  OF  THE  FACE. 

Of  the  fourteen  bones  of  the  face,  twelve  are  in  pairs :  the  superior 
maxillary,  palate,  lachrymal,  nasal,  turbinated,  and  malar  bones;  the 
remaining  two  are  single  and  symmetrical :  the  vomer,  situated  in  the  par- 
tition of  the  nose,  and  the  inferior  maxillary  bone. 

1  Small,  bregmatic,  or  occipital  font-  4  Ossa  inlercalaria;  o.  suturarum;  o. 
anel.  Wormiana;  o.  triquetra;  o  epactalia;  o. 

2  Sphenoid  fontanel.  raphogeminantia  ;  o.  triangularia  Blasii; 

3  Mastoid  fontanel ;    fonticulus    mas-  claves  calvariae. 
toideus  ;  f.  Casserii.  5  Os  antiepilepticum. 


76 


THE   SKELETON. 


THE  SUPERIOR  MAXILLARY  BONE. 

The  Superior  Max'illary  bone1  forms  with  its  fellow  the  upper  jaw, 
and  contributes  in  the  construction  of  the  roof  of  the  mouth,  the  nasal 
fossae,  the  orbits,  the  cheeks,  and  the  spheno-maxillary  fossa3. 


SUPERIOR  MAXILLARY  BONE  OF  THE  LEFT  SIDE, 
outer  view.  1,  body;  2,  tuberosity;  3,  alveolar 
border;  4,  orbital  plate;  5,  nasal  process;  6,  nasal 
notch;  7,  nasal  spine;  8,  lachrymal  groove;  9,  en- 
trance of  the  infra-orbital  canal ;  10,  infra-orbital 
foramen ;  11,  orifices  of  the  posterior  dental  canals ; 
12,  malar  process ;  13,  articulation  for  the  internal 
angular  process  of  the  frontal  bone;  14,  incisor 
teeth;  15,  canine  tooth;  16,  premolar  teeth;  17, 
large  molar  teeth. 


SUPERIOR  MAXILLARY  BONE  OF  THE  LEFT  SIDE, 
inner  view.  1,  nasal  surface  of  the  body ;  2,  sur- 
face for  the  palate  bone ;  3,  alveolar  border ;  4,  orb- 
ital plate ;  5,  nasal  process ;  6,  ridge  for  the  articu- 
lation of  the  turbinated  bone ;  7,  nasal  spine ;  8, 
groove  contributing  to  form  the  lachrymo-nasal 
duct;  9,  maxillary  sinus;  10,  palate  plate,  its  ar- 
ticulating border  for  the  right  maxillary  bone ;  11, 
incisive  foramen  continuous  with  the  naso-palatine 
canals ;  12,  tuberosity  ;  13,  articular  extremity  for 
the  internal  angular  process  of  the  frontal  bone; 
14.  incisor  teeth;  15,  canine  tooth;  16,  premolar 
teeth  ;  17,  large  molar  teeth. 

The  body  of  the  bone,  independent  of  its  processes,  is  wedge-shaped, 
and  is  hollowed  into  a  large  cavity,  the  max'illary  si'nus,2  which  com- 
municates, by  a  large  irregular  orifice,  through  the  inner  wall,  with  the 
nasal  fossa.  Above  the  orifice  just  mentioned,  the  inner  surface  of  the 
body  articulates  with  the  lachrymal  and  ethmoid  bones,  and  behind  it, 
with  the  palate  bone. 

The  anterior  surface  of  the  body,  forming  part  of  the  cheek,  is 
depressed3  and  is  bounded  above  by  the  infra-orbital  margin.  Just 


1  Os  maxillare  superius ;  upper  jaw- 
bone ;    maxilla   sup. ;    mandibula  sup. ; 
maxilla  syncrania. 

2  S.  maxillaris ;    antrum    Highmoria- 


num ;  nntrum  of  Highmore ;  genyan- 
trum ;  gnathantrum;  sinus  genge  pitui- 
tarius;  antrum  genae. 

3  Fovea  maxillaris ;  canine  fossa. 


THE  SKELETON.  77 

below  the  latter  is  the  in'fra-orb'ital  fora'men,1  which  transmits  the 
infra-orbital  nerve  and  blood-vessels. 

The  posterior  convex  surface  of  the  body  constitutes  the  tuberos'ity,2 
and  contributes  to  form  the  spheno-maxillary  fossa.  It  presents  a  per- 
forated surface ;  and  several  of  the  larger  orifices  are  the  commencement 
of  the  posterior  dent'al  canals',3  which  are  narrow  passages  transmit- 
ting nerves  and  arteries  to  the  molar  teeth. 

The  upper  surface  of  the  body,  or  orb'ital  plate,4  forms  the  floor  of 
the  orbit,  and  terminates  behind  in  an  obtuse  border,  which  is  the  lower 
boundary  of  the  spheno-maxillary  opening.  From  the  latter  border, 
the  infra-orb'ital  canal'5  proceeds  forward  in  the  orbital  plate,  and  term- 
inates at  the  corresponding  foramen.  From  the  canal  two  fine  passages, 
the  anterior  dent'al  canals',6  descend  in  the  outer  wall  of  the  body,  and 
conduct  arteries  and  nerves  to  the  anterior  teeth.  Both  the  anterior 
and  posterior  dental  canals  are  partially  visible  within  the  maxillary 
sinus. 

At  the  lower  part  of  the  superior  maxillary  bone  is  the  thick  pyra- 
midal ridge,  called  the  alve'olar  border,7  which  arches  from  behind  for- 
ward and  inward,  and  projects  obliquely  downward  and  outward.  The 
free  margin  presents  the  orifices  of  a  number  of  deep  conical  pits,  the 
alve'oli,8  or  sockets  for  the  insertion  of  the  teeth.  The  outer  surface  of 
the  border  is  marked  by  alternating  vertical  ridges  and  depressions,  cor- 
responding with  the  alveoli  and  their  intervals.  The  posterior  extremity 
of  the  border  is  rough,  and  abuts  against  the  pyramidal  process  of  the 
palate  bone.  The  anterior  extremity  is  likewise  rough,  and  articulates 
with  the  corresponding  border  of  the  opposite  bone. 

Above  the  anterior  extremity  of  the  alveolar  border  is  a  pointed 
process,  the  na'sal  spine,9  prolonged  backward  into  a  ridge,  to  which 
the  cartilage  of  the  partition  of  the  hose  is  attached.  To  the  outer 
side  of  the  spine  is  a  concave  notch,  which  forms  part  of  the  anterior 
nasal  orifice.  The  margin  of  the  na'sal  notch  in  the  white  race  is  usually 
acute,  but  is  rounded  off  to  the  anterior  surface  of  the  alveolar  border  in 
the  black  race. 

Above  the  notch  just  mentioned  is  a  plate  of  bone,  the  na'sal  proc'ess,10 

1  F.  infra  orbitale.  7  Processus,  or  limbus  alveolaris. 

2  Tuberositas  maxillaris.  8  Alveoli    dentis  ;    cavernae   dentium  ; 

3  Canales,  or  canaliculi  alveolares,  or  odontobothria ;   mortarioli. 
dentales  posteriores.  9  Spina  nasalis ;  s.  nasalis  anterior. 

*  Planum  orbitale.  w  Processus  nasalis ;  p.  frontalis  ;  p. 

5  Canalis  infra-orbitalis.  ascendens. 

6  Canalis  alveolaris,  ordentalismedius 
et  anterior. 


78  THE   SKELETON. 

which  extends  upward  to  join  the  internal  angular  process  of  the  frontal 
bone.  Its  outer  surface  forms  part  of  the  side  of  the  nose ;  and  its  inner 
surface,  directed  toward  the  cavity  of  the  latter,  is  concave  and  bounded 
below  by  a  ridge  for  the  attachment  of  the  turbinated  bone.  Its  ante- 
rior border  is  thick  and  rough  for  junction  with  the  nasal  bone.  Its  pos- 
terior border  joins  the  lachrymal  bone,  and  is  grooved  to  form  part  of 
the  naso-lachrymal  canal. 

From  the  internal  part  of  the  base  of  the  alveolar  border  there  pro- 
jects horizontally  inward,  the  pal'ate  plate,1  which  contributes  to  form 
the  roof  of  the  mouth  and  the  floor  of  the  nose.  Its  nasal  surface  is 
smooth  and  concave  ;  and  its  oral  surface,  continuous  with  the  inner  one 
of  the  alveolar  border,  is  vaulted  and  rough.  Its  inner  border  rises  into 
a  ridge  which  articulates  with  the  vomer,  and  forms  a  thick  rough  surface 
for  junction  with  that  of  the  opposite  bone.  The  posterior  border  is  thin 
and  rough,  and  joins  the  palate  bone. 

From  the  outer  part  of  the  body  there  projects  a  strong  protuberance, 
the  ma'lar  proc'ess,2  which  presents  a  large  trilateral  roughened  surface 
for  the  support  of  the  malar  bone. 

Between  the  anterior  extremity  of  the  alveolar  border  and  the  palate 
plate  of  the  superior  maxillary  bone,  the  na'so-pal'atine  canal'3  descends 
from  the  nasal  fossa,  and,  converging,  forms  with  that  of  the  opposite 
bone,  in  the  intermediate  suture,  the  anterior  pal'atine  fora'men.4 
From  the  canal  and  foramen  a  fine  fissure  may  be  traced  a  short  distance 
outwardly,  which  is  a  vestige  of  the  separation,  existing  in  other 
mammals,  of  that  portion  of  the  bone  containing  the  incisive  teeth,  and 
called  the  intermaxillary  bone.  The  representative  of  the  latter  is  ob- 
scurely indicated  in  the  human  embryo  prior  to  the  third  month ;  the 
line  of  its  separation  dividing  off  the  incisive  portion  of  the  alveolar 
border  and  the  lower  third  of  the  nasal  process. 

THE  PALATE  BONE. 

The  Pal/ate  bone5  is  situated  at  the  back  part  of  the  superior  max- 
illary bone,  between  it  and  the  sphenoid  bone.  It  contributes,  with  its 
fellow,  to  form  the  mouth,  nasal  fossae,  and  orbits.  It  has  the  outline  of 
the  letter  L,  consisting  of  a  horizontal  and  vertical  plate,  together  with 
smaller  processes. 

1  P.  palatinus.  4  F.  palatinum  anterius  ;  f.  incisivum  ; 

2  P.  zygomaticus.  f.  alveolare  anterius  ;  f.  coecum. 

3  Canalis,    or    ductus  naso-palatinus,  5  Os  palatinum ;  o.  palati. 
or  incisivus. 


THE   SKELETON. 


79 


The  horizontal  or  pal'ate  plate1  is  square,  and  contributes  a  smooth 
concave  surface  to  the  floor  of  the  nose,  and  a  smaller  surface  to  the  hard 
palate.  Its  inner  border  rises  into  a  crest2  and  articulates  with  that  of 


FIG.  53. 


POSTERIOR  VIEW  OF  THE  RIGHT  PALATE  BONE.  1, 
palate  plate;  2,  nasal  plate;  3,  pyramidal  process; 
4,  articular  border  for  the  left  palate  bone;  5, 
palate  spine;  6,  ridge  for  junction  with  the  turbi- 
nated  bone ;  7,  spheno-palatiue  notch,  between  8,  the 
orbital,  and  9,  the  sphenoidal  process;  10,  groove 
for  the  internal  pterygoid  process  of  the  sphenoid 
bone ;  11,  position  of  the  posterior  palatine  fora- 
men. 


EXTERIOR  VIEW  OF  THE  RIGHT  PALATE  BONE. 
1,  rough  surface  articulating  with  the  superior 
maxillary  bone,  and  diminishing  the  aperture  of 
the  maxillary  sinus  ;  2,  posterior  palatine  canal ; 
completed  by  the  tuberosity  of  the  superior  max- 
illary bone ;  3,  spheno-palatine  notch ;  4,  5,  6,  orb- 
ital process;  4,  surface  directed  toward  the  ptery- 
go-maxillary  fossa;  5,  orbital  surface ;  6,  maxillary 
border ;  7,  sphenoidal  process  ;  8,  pyramidal  process. 


the  opposite  side;  the  crests  of  the  conjoined  palate  plates  aiding  in  the 
support  of  the  vomer,  and  projecting  backward  into  a  pointed  process, 
the  palate  spine.3  The  anterior  border  of  the  palate  plate  articulates 
with  that  of  the  superior  maxillary  bone ;  and  the  posterior  crescentic 
border  has  the  soft  palate  attached  to  it. 

The  vertical  or  na'sal  plate4  is  thinner  than  the  other,  and  extends 
from  it  to  the  base  of  the  cranium.  Its  inner  or  nasal  surface  is  divided 
into  two  parts  by  a  horizontal  ridge,5  with  which  the  turbinated  bone 
articulates.  Its  outer  surface  is  divided  by  a  vertical  ridge  bounding 
a  groove,6  which,  by  the  approximation  of  the  sphenoid  and  superior  max- 
illary bones,  is  converted  into  the  posterior  pal'atine  canal V  descend- 
ing from  the  pterygo-maxillary  fossa  to  the  hard  palate.  The  posterior 
portion  of  the  outer  surface  of  the  nasal  plate  articulates  with  the  in- 
ternal pterygoid  process,  and  the  anterior  portion  with  the  maxillary 
bone,  partially  closing  the  entrance  of  the  maxillary  sinus. 


1  Pars  palati ;  p.  horizontalis. 

2  Crista  nasalis. 

3  Spina  palatina  ;  s.  nasalis  posterior. 

4  Pars  nasalis  ;  p.  perpendicularis. 


5  Crista  turbinalis  ;  c.  t.  inferior. 

6  Sulcus  pterygo-palatinus. 

T  Canalis  palatina  posterior  ;  c.  ptery- 
go-palatina. 


80 


THE   SKELETON. 


At  the  .upper  border  of  the  nasal  plate  is  a  large,  round  notch,  which, 
in  conjunction  with  the  under  part  of  the  body  of  the  sphenoid  bone, 
is  converted  into  the  sphe'no-pal'atine  fora'men1  communicating  from 
the  pterygo-maxillary  fossa  with  the  nasal  fossa. 

Behind  the  notch  just  mentioned  is  the  sphenoid'al  proc'ess,2  which 
articulates  with  the  under  part  of  the  body  of  the  sphenoid  bone.  In 
the  upper  border  of  this  process  is  a  groove,  which,  in  conjunction  with 
the  latter  bone,  is  converted  into  the  pter'ygo-pal'atine  canal'.3 

In  advance  of  the  notch  indicated,  is  the  orVital  proc'ess,4  which  is 
received  between  the  orbital  plates  of  the  superior  maxillary  and  ethmoid 
bones  at  the  posterior  inferior  part  of  the  orbit,  where  it  closes  the  poste- 
rior ethmoidal  sinuses. 

At  the  posterior  angle  of  conjunction  of  the  nasal  and  palate  plates 
of  the  palate  bone,  there  projects  the  pyramidal  proc'ess,5  which  occu- 
pies the  notch  of  the  pterygoid  processes  of  the  sphenoid  bone.  Some- 
times it  completely  incloses  the  lower  part  of  the  posterior  palatine 
canal ;  and  not  unfrequently  it  is  pierced  by  one  or  two  branches  from 
the  latter  descending  in  the  same  direction. 


FIG.  55. 


THE  LACHRYMAL  BONE. 

The  Lach'rymal  bone,6  the  smallest  of  those  of  the  face,  is  situated 
one  at  the  fore  part  of  the  inner  wall  of  each 
orbit.  It  contributes  to  form  the  latter,  the 
lachrymo-nasal  duct,  the  nasal  fossa,  and  the 
anterior  ethmoidal  sinuses. 

It  consists  of  a  thin,  oblong  square  plate, 
articulating  above,  behind,  and  below  with  the 
orbital  plates  of  the  frontal,  ethmoid,  and 
maxillary  bones,  and  in  front  with  the  nasal 
process  of  the  latter  bone. 

The  outer  surface  forms  part  of  the  inner 
wall  of  the  orbit,  and  in  advance  contributes  a 
fossa  or  groove7  to  the  lach/rymo-na'sal  duct.8 
The  outer  surface  closes  in  the  anterior  eth- 
moidal sinuses. 


EXTERNAL  VIEW  OP  THE  RIGHT 
LACHRYMAL  BONE.  1,  orbital  sur- 
face;  2,  lachrymal  fossa;  3,  small 
process  bounding  the  latter  iufe- 
riorly;  4,  frontal  border;  5,  eth- 
moidal border;  6,  maxillary  bor- 
der; 7,  process  articulating  with 
the  turbinated  bone. 


1  F.  spheno-palatinum. 

2  Processus  sphenoidalis ;    apophysis 
pterygoideus. 

3  C.  pterygo-palatina. 

4  P.  orbitalis. 


5  Pterygoid  process  ;  apophysis  sphe- 
noidalis. 

6  Os  lachrymale  ;  os  unguis  ;    ungui- 
form  bone. 

7  Lachrymal  fossa. 

8  Ductus  ad  nasum. 


THE   SKELETON.  81 

From  the  anterior  inferior  angle  a  process1  projects  downward,  which 
joins  with  one  from  the  turbinated  bone,  and  serves  to  prolong  the  lach- 
rymo-nasal  duct. 

THE  NASAL  BONE. 

The  Na'sal  bone2  projects  from  the  root  of  the  nose  downward  and 
forward,  and  with  its  fellow,  together  with  the  nasal  processes  of  the 
superior  maxillary  bones,  forms  the  bridge  of  the  nose. 

It  is  irregularly  quadrate,  and  thicker  and  narrower  above  than 
below,  and  not  unfrequently  is  so  narrow 
as  to  assume  a  fan-like  shape.  In  its  length 
it  presents  a  sigrnoid  curve,  though  occasion- 
ally it  is  simply  concave  in  this  direction. 
The  outer  surface  is  smooth,  transversely  con- 
vex, and  generally  presents  a  small  but  con- 
spicuous foramen3  near  its  middle.  The  inner 
surface,  directed  toward  the  corresponding  na-  f1$| 

sal  fossa,  is  transversely  concave,  and  presents  Lr  ^ 

a  longitudinal  groove  for  the  accommodation 
of  a  branch  of  the  nasal  nerve.  ANTERI°*  TV"", 1E"  NA' 

SAL  BONE.    1,  frontal  border ;  2,  na- 
The  Upper    border  Of  the  nasal  bone  is  thick      sal  border;   3,  maxillary  border: 

and  roughened  for  articulation  with  the  frontal  4' lower  border ;  5' nasal  foramen' 
bone ;  the  lower  border  is  thin  and  notched,  and  forms  the  superior 
boundary  of  the  anterior  nasal  orifice.  The  inner  border  is  thick  above, 
narrows  off  below,  and  conjoins  with  that  of  the  opposite  bone.  The 
outer  border  is  beveled  off  and  overlapped  by  the  corresponding  border 
of  the  nasal  process  of  the  superior  maxillary  bone. 


THE  TURBINATED  BONE. 

The  Tur'binated  bone*  is  quite  rudimentary  in  comparison  with  the 
corresponding  one  of  most  other  animals,  in  which  it  often  acquires  an 
extraordinary  degree  of  development,  as  the  student  may  observe  in  any 
of  the  common  carnivorous  animals — the  cat,  dog,  weasel,  bear,  etc. 
It  projects  horizontally  from  the  outer  wall  of  the  nasal  fossa,  and 
separates  the  middle  and  inferior  meatus. 

The  bone  presents  the  form  of  an  irregular  scroll,  with  a  rough 
convex  surface  directed  toward  the  partition  of  the  nose,  and  a  con- 

1  Hamulus  lacbrymalis.  *  Os  turbinatum ;  o.  t.  inferius ;  spongy 

2  Os  nasale  ;  os  nasi.  bone;  o.  spongiosum;  concha  inferior;  c. 
8  F.  nasalis.  veneris  ;  buccinum. 

6 


82 


THE   SKELETON. 


cave  surface  directed  outwardly. 


FIG.  57. 


Its  lower  part  is  thick  and  spongy; 
its  anterior  extremity  joins  the 
transverse  ridge  at  the  root  of  the 
nasal  process  of  the  superior  max- 
illary bone ;  and  its  posterior  nar- 
rower extremity  articulates  with  a 
like  ridge  of  the  palate  bone. 

From  the  middle  of  the  upper 
border  a  hook-like  plate1  overhangs 
the  inferior  edge  of  the  entrance  to 
the  maxillary  sinus;  and  a  small 
process2  ascending  from  this  plate 
diminishes  the  aperture  of  the  lat- 
ter, and  frequently  joins  a  process 
from  the  ethmoid  bone.  In  advance  of  the  hook-like  plate,  another  small 
process3  ascends  to  join  one  from  the  lachrymal  bone,  and  assists  in  the 
formation  of  the  lachrymo-nasal  duct. 


EXTERNAL  VIEW  OF  THE  RIGHT  TCRBINATED  BO\E. 
1,  anterior  extremity  articulating  with  the  superior 
maxillary  bone ;  2,  posterior  extremity  articulat- 
ing with  the  palate  bone ;  3,  hook-like  plate  over- 
hanging the  lower  border  of  the  maxillary  sinus. 
The  process  in  advance  of  it  above  joins  the  lachry- 
mal bone  to  contribute  in  the  formation  of  the 
lachrymo-nasal  duct.  4,  inferior,  obtuse  border. 


FIG.  58. 


THE   VOMER. 

The  Vo'mer4  is  a  lozenge-shaped  plate  of  bone,  situated  at  the  back 

part  of  the  partition  of  the  nose. 

Its  lateral  surfaces  form  part  of  the  inner  wall  of  the  nasal  fossa?. 

The  upper  border  is  grooved  to  re- 
ceive the  rostrum  of  the  sphenoid 
bone,  and  its  edges5  are  reflected  to 
join  a  thin  plate  springing  out  of 
the  root  of  the  pterygoid  processes. 
The  lower  border  articulates  with 
the  crest  formed  at  the  conjunction 
of  the  palate  plates  of  both  the 
superior  maxillary  and  palate  bones. 
The  anterior  border  is  grooved  to 
receive  the  cartilage  of  the  nasal 
partition,  and  at  its  upper  part  ar- 
ticulates with  the  nasal  plate  of  the 
ethmoid  bone.  The  posterior  bor- 
der is  thin  and  crescentic,  and 

forms  the  oblique  line  of  separation  of  the  posterior  nasal  orifices. 


LEFT  SIDE  OF  THE  VOMER.  1, 1,  broad  groove  re- 
ceiving the  rostrum  of  the  sphenoid  bone ;  2,  2, 
inferior  border  articulating  with  the  palate  plates 
of  the  superior  maxillary  and  palate  bones;  3, 
posterior  border,  the  dividing  line  of  the  posterior 
Dares;  4,  4,  grooved  border  receiving  a  narrow 
slip  of  cartilage,  situated  between  the  vomer  and 
the  nasal  plate  of  the  ethmoid  bone ;  5,  5,  border 
for  the  cartilaginous  septum  of  the  nose;  6,  6,  na- 
sal surface. 


1  Processus  maxillaris.  2  P.  ethmoidalis.  3  P.  lachrymalis. 

4  Osvomeris;  aratrum.  5  Also  vomeris. 


THE   SKELETON. 


83 


THE  MALAR  BONE. 

The  Ma'lar  or  cheek  bone1  forms  the  most  prominent  part  of  the 
cheek,  and  contributes  to  the  construction  of  the  orbit  and  temporal 
fossa.  It  is  quadrangular,  and  rests  by  a  broad,  trilateral,  rough  surface 
upon  the  malar  process  of  the  superior  maxillary  bone. 

From  the  upper  part  a  strong  front/al  proc'ess  ascends  to  articulate 
with  the  external  angular  process 
of  the  frontal  bone ;  and  from  the 
back  part  projects  a  strong  zygo- 
mat'ic  proc'ess  to  articulate  with 
the  corresponding  process  of  the 
temporal  bone. 

The  upper,  anterior,  concave  bor- 
der forms  the  inferior  and  external 
margin  of  the  orbit.  From  this 
border  there  proceeds  backward 
and  inward  the  orb'ital  plate, 
which  separates  the  orbit  from  the 
temporal  fossa,  articulates  with  the 
corresponding  plates  of  the  max- 
illary, sphenoid,  and  frontal  bones, 
and  contributes  to  the  spheno-maxillary  foramen. 

The  posterior  border  of  the  bone,  included  between  the  frontal  and 
zygomatic  processes,  is  sigmoid,  and  gives  attachment  to  the  temporal 
fascia.  The  inferior  border  is  convex  and  rugged,  and  contributes  about 
one-half  to  the  extent  of  the  lower  margin  of  the  zygoma. 

The  fa/cial  surface,  directed  more  or  less  outwardly  and  forward,  is 
for  the  most  part  convex,  and  pretty  constantly  presents  one  or  two  con- 
spicuous foramina,  which  are  continuous  with  canals2  from  the  orbital  and 
temporal  surfaces.  The  temporal  surface  is  concave,  directed  backward, 
and  forms  the  anterior  part  of  the  temporal  fossa. 


OUTER  VIEW  OF  THE  RIOHT  MALAR  BONE.  1,  ex- 
ternal or  facial  surface;  2,  malar  foramen ;  3,  front- 
al process;  4,  5,  orbital  border;  6,  maxillary  bor- 
der; 7,  zygomatic  process;  8,  temporal  border;  9, 
inferior  border. 


THE  INFERIOR  MAXILLARY  BONE. 

The  Inferior  Max'illary,  or  lower  jaw  bone,3  is  the  second  of  the 
symmetrical  bones  of  the  face,  in  which  it  occupies  the  lower  semi- 


1  Os  malare ;  o.  malse ;  o.  zygomat- 
icum ;  o.  jugale ;  o.  suboculare  ;  o.  hypo- 
pium  ;  o.  pudicum ;  o.  jugamentum  ;  o. 
genoe. 


2  C.  zygomaticus  facialis,   or   tempo- 
ralis. 

3  Maxilla  inferior ;  os  maxillare  infe- 
rius  ;  inferior  maxilla  ;  mandibula. 


84 


THE  SKELETON. 


FIG.  60. 


circumference.     It  is  also  the  largest  and  strongest  bone  of  the  face,  and 
is  the  only  movable  one  of  the  skull.     From  the  other  bones  of  the  face 

it  is  actually  isolated  through  con- 
tact of  the  teeth,  and  it  articulates 
with  the  cranium  at  the  glenoid 
cavities  of  the  temporal  bones.  It 
is  divisible  for  description  into  the 
body,  and  rami  or  branches. 

The  body  is  the  curved  portion 
of  the  bone  supporting  the  teeth. 
Its  outer  surface  is  convex,  and  at 
the  middle  presents  a  prominent 
line,  indicating  the  early  separation 
of  the  bone  into  two  pieces,  and 
hence  called  the  sym/physis.  The 
prominent  portion  of  the  body  in 
front  is  the  chin,1  which  in  the 
negro  is  vertical  or  even  receding. 
Its  lower  protuberant  part  is  the  men'tal  protu/berance,2  on  each  side 
of  which  is  the  men'tal  fora'men,3  the  termination  of  the  inferior  dental 
canal. 

The  inner  surface  of  the  body  presents  at  the  lower  part  of  the  sym- 
physis  the  men'tal  tu/bercle.4  On  each  side,  below  the  position  of  the 
molar  teeth,  is  the  oblique  mo'lar  ridge,5  to  which  is  attached  the  mus- 
cular floor  of  the  mouth,  Beneath  the  ridge  the  surface  is  slightly  im- 
pressed by  the  position  of  the  submaxillary  gland,  and  the  lower  obtuse 
border  of  the  bone  is  its  base. 

The  upper  portion  of  the  body  forms  its  alve'olar  border,6  which  is 
constructed  on  the  same  plan,  and  for  the  same  purpose  as  in  the  superior 
maxillary  bones.  In  relation  with  the  corresponding  part  of  the  latter, 
it  is  usually  vertical  in  position,  though  in  the  negro  it  is  generally 
directed  a  little  forward  and  upward. 

The  ram'i7  are  the  quadrate  plates  ascending  from  the  posterior 
extremities  of  the  body,  reaching  as  high  as  the  zygomatic  arches. 
Their  outer  surface  forms  a  nearly  vertical  plane.  Near  the  middle  of 


INFERIOR  MAXILLARY  BONE.  1,  body ;  2,  ramus ; 
3,  symphysis;  4,  base;  5,  angle;  6,  mental  fora- 
men ;  7,  condyle ;  8,  coronoid  process ;  9,  semilunar 
notch;  10,  inferior  dental  foramen,  the  entrance  of 
the  corresponding  canal;  11,  alveolar  border;  12, 
incisor  teeth;  13,  canine  tooth ;  14,  premolars ;  15, 
large  molars. 


1  Mentum. 

2  Protuberantia  mentalis. 

3  F.  mentale  ;  f.  maxillare  anterius. 

4  Spina  mentalis  interna  ;  spinae  men- 
tales;  internal  mental  tubercle. 


5  Mylo-hyoid    ridge ;     linea   mylohy- 
oidea ;  1.  obliqua  interna. 

6  Processus  alveolaris. 

7  The  name  rami  is  frequently  applied 
by  comparative   anatomists  to  the  two 
halves  of  the  jaw. 


THE   SKELETON.  85 

the  inner  surface  is  the  entrance1  of  the  inferior  dent/al  canal',2  which 
descends  to  the  body  of  the  bone  and  proceeds  beneath  the  alveolar  bor- 
der to  terminate  at  the  mental  foramen.  The  entrance  of  the  canal  is 
bounded  by  a  prominent  crest,3  which  gives  attachment  to  the  spheno- 
maxillary  ligament ;  and  below  it,  there  descends  a  groove  for  the  accom- 
modation of  a  small  nerve. 

The  posterior  border  of  each  rarnus  is  obtuse,  and  terminates  below  in 
the  angle,4  which  is  more  or  less  obtuse  in  its  relation  with  the  base  of 
the  bone.  The  inner  and  outer  surfaces  of  the  angle  are  variably 
rugged,  for  the  attachment  of  two  of  the  masticating  muscles.  The 
anterior  border  of  the  ramus  is  sigmoid  in  its  descent  to  the  outer  side 
of  the  body,  where  it  terminates  just  exterior  to  the  last  tooth. 

The  upper  border  of  the  ramus  exhibits  a  large  semilunar  notch,5 
in  advance  of  which  is  a  flat  conical  eminence,  th.e  cor'onoid  proc'ess,6 
into  which  the  temporal  muscle  is  inserted.  Posterior  to  the  notch  is 
another  process,  which  supports  a  transverse  articular  convexity,  the 
con'dyle,7  and  its  narrow  part  below  constitutes  the  neck8  of  the  jaw, 
the  inner  side  of  which  presents  a  depressed  surface,  directed  forward, 
for  the  attachment  of  the  external  pterygoid  muscle. 


STRUCTURE  AND  ARTICULATION  OF  THE  BONES  OF 
THE  FACE. 

The  bones  of  the  face  are  remarkable  for  their  light  and  laminar  char- 
acter, with  the  exception  of  the  inferior  maxilla,  which  is  the  stoutest  and 
strongest  bone  of  the  skull,  and  contains  within  it,  like  most  of  the  cra- 
nial bones,  a  quantity  of  spongy  substance. 

All  the  bones  of  the  face,  except  the  lower  jaw,  are  firmly  and  immov- 
ably articulated  with  one  another  and  with  the  cranium. 

The  face  and  cranium  together  constitute  the  skull,  or  bony  portion  of 
the  head. 

Across  the  root  of  the  nose,  at  the  external  angular  processes  of  the 
frontal  bone,  and  at  the  zygomatic  arches,  the  face  articulates  by  well- 
marked  serrate  sutures9  with  the  cranium.  Among  themselves  the  bones 
of  the  face  generally  articulate  by  the  mutual  adaptation  of  more  or  less 

1  Foramen  maxillare  internum  ;  infe-  5  Incisura  semilunaris ;  i.  sigmoidea. 
rior  dental  foramen.  6  Processus  coronoideus. 

2  Canalis  maxillaris ;  c.  alveolaris  in-  »  Condylus ;  capitulum. 
ferior.  8  Cervix ;  collum. 

3  Lingula.  4  Angulus  maxillae.  9  The  transverse  facial  suture. 


86 


THE   SKELETON. 


roughened  borders.1  The  different  sutures  are  named  from  the  bones 
they  connect,  or  from  their  position,  and  thus  we  have  a  na'so-front'al 
su/ture,  an  intermaxillary  su/ture,  a  middle  and  transverse  pal'ate 
su/ture,  etc. 

THE  TEMPEKO-MAXILLARY  ARTICULATION. 

The  movable  articulation  of  the  inferior  maxillary  bone  is  formed  be- 
tween the  condyle  of  the  latter  and  the  glenoid  cavity  and  tubercle  of  the 
temporal  bone,  which  are  invested  with  cartilage.  The  motions  of  the 
lower  jaw  are  as  follows :  1.  the  opening  and  shutting  of  the  mouth,  in 
which  the  condyles  roll  on  their  axes  in  the  glenoid  cavities,  as  in  the 
movement  of  a  hinge ;  2.  the  movement  of  the  lower  jaw  forward  and 
backward,  in  which  the  condyles  move  forward  from  the  glenoid  cavities 
upon  the  glenoid  tubercles  and  back  again ;  and  3.  the  movement  from 
side  to  side,  when  the  condyles  move  alternately  and  obliquely  from  the 
glenoid  cavities  to  the  glenoid  tubercles  and  back  again. 

The  hinge-like  or  downward  and  upward  movement  of  the  lower  jaw 
is  the  act  of  biting;  the  movements  of  the  jaw  forward  and  backward, 
and  from  side  to  side,  are  those  of  mastication  or  chewing. 

FIG.  61.  FIG.  62. 


VERTICAL  SECTION  OP  THE  ARTICULATION  OF  THE  EXTERNAL  VIEW  OF  THE  TEMPERO-MAXILLARY  AR- 
LOWER  JAW.  1,  is  placed  above  the  glenoid  cav-  TICULATION.  1,  zygoma;  2,  glenoid  tubercle,  3,  ra- 
ity ;  2,  glenoid  tubercle ;  3,  inter-articular  cartilage  mu8  of  the  inferior  maxillary  bone;  4,  mastoid 
dividing  the  joint  into  two  cavities, 4  and  5 ;  6,  an  process;  5,  external  lateral  ligament;  6,  stylo- 
inter-articular  cartilage  separated  from  a  joint,  to  maxillary  ligament,  a  process  of  the  cervical  fascia, 
exhibit  its  form. 

The  articulation  of  the  lower  jaw  is  rendered  more  movable  by  an 
in'terartic'ular  fi'bro-car'tilage,2  which  is  a  discoidal  plate  horizontally 
dividing  the  joint  into  two  cavities,  each  lined  with  a  synovial  mem- 
brane. The  margin  of  the  fibro-cartilage  is  thickened  and  attached  to 
the  capsular  ligament;  and  it  is  signioid  in  section  antero-posteriorly. 
It  follows  the  movements  of  the  condyle,  and  reduces  the  force  of  its 
impressions. 


1  Suturse  harmonise. 


2  Cartilago-interarticularis. 


THE   SKELETON. 


87 


FIG.  63. 


The  cap'sular  lig'ament,  inclosing  the  joint,  is  thin  and  loose,  and 
is  attached  above  to  the  articular  margin  of  the  glenoid  cavity  and 
tubercle,  and  below  to  the  neck  of  the  lower  jaw. 

The  external  lat'eral  lig'ament1  strengthens  the  former  on  the  outer 
side  of  the  joint.  It  consists  of  a  short,  strong  band  attached  to  the 
root  of  the  zygomatic  process,  and  extending  downward  and  backward 
to  the  neck  of  the  lower  jaw. 

GENERAL  CONFORMATION  AND  POSITION  OF  THE  FACE. 

The  Face  is  placed  beneath  the  fore  part  of  the  cra'nium,  together 
with  which  it  forms  the  skull, 
as  previously  stated.  In  out- 
line it  has  the  shape  of  a 
wedge-like  segment  from  an 
oval  figure.  The  rounded 
portion  of  the  segment  is 
formed  by  the  front  and  sides 
of  the  face;  the  sectional 
surfaces  are  formed  by  the 
conjunction  of  the  latter  with 
the  cranium  and  the  base  of 
the  lower  jaw;  and  the  apex, 
which  is  truncated,  is  formed 
by  the  back  borders  of  the 
rami  of  the  lower  jaw. 

The  face  is  mainly  consti- 
tuted of  a  series  of  receptacles 
for  the  accommodation  and 
protection  of  the  organs  of 
sight,  smell,  taste,  and  others 
belonging  to  the  commence- 
ment of  the  alimentary  appa- 
ratus. In  relation  with  the 
size  of  the  cranium,  it  is 
smaller  than  in  other  mam- 
mals. In  the  white  race  it 
forms  about  one-fifth  of  the 

bulk  Of  the    Skull,  but   in    the       onoid  process ;?,  neck  supporting  the  condyle ;  m,  angle;  n, 

inferior  races  is  considerably     lachrym°-nasal  duct- 

larger.     The  greater  its  size  in  relation  with  that  of  the  cranium,  the 


THE  SKULL,  SEEN  PARTLY  IN  FRONT  AND  ON  THE  RIGHT   SIDE- 

1,  frontal  bone;  2,  parietal  bone;  3,  temporal  bone,  its  squa- 
mous  portion  ;  4,  the  sphenoid  bone,  temporal  surface  of  its 
great  wing ;  5,  ethmoid  bone,  its  orbital  surface ;  6,  superior 
maxillary  bone;  7,  malar  bone;  8,  lachrymal  bone;  9,  nasal 
bone;  10,  inferior  maxillary  bone,  a,  orbital  plate  of  the 
frontal  bone;  ft,  temporal  surface;  c,  orbital  surface  of  the 
great  wing  of  the  sphenoid  bone;  d.  mastoid  portion  of  the 
temporal  bone;  e,  orbital  surface  of  the  malar  bone;  /,  orb- 
ital plate  of  the  superior  maxillary  bone ;  g,  infra-orbital 
foramen;  h, mental  foramen;  t,  symphysis;.;',  ramus;  k,  cor- 


1  Ligamentum  maxilloB  laterale  externum ;  membrana  articularis  ligamentosa. 


88  THE   SKELETON. 

less  does  it  project  in  advance  of  the  latter ;  and  with  its  proportionate 
diminution,  as  its  front  approaches  a  line  vertical  with  the  forehead,  the 
nearer  does  it  approximate  the  ideal  standard  of  an  intellectual  coun- 
tenance. Hence  the  advancing  forehead  and  retiring  face  are  most 
striking  features  in  the  white  race,  especially  in  its  more  cultivated  fami- 
lies ;  while  the  prominent  face,  with  large  jaws,  and  receding  forehead, 
are  coexistent  with  the  less  intellectual  character  of  the  inferior  races 
of  men. 

The  angle  of  inclination  of  the  fore  part  of  the  skull  is  viewed  to  deter- 
mine the  comparative  degree  of  development  of  the  face  and  cranium,  and 
in  some  measure  to  form  an  estimate  of  the  mental  capacity  of  races  and 
individuals.  Though  open  to  many  objections,  such  as  variations  being 
produced  in  the  angle,  from  the  presence  or  absence  of  teeth,  from  the 
different  degrees  of  development  of  the  frontal  sinuses,  from  projection  of 
the  forehead  in  hydrocephalus,  or  its  depression  by  artificial  means,  yet 
independently  of  these  and  similar  reasons,  the  fa'cial  angle1  is  still  looked 
upon,  in  some  measure,  as  an  index  of  intellectual  character.  The  usual 
method  of  estimating  the  angle,  is  by  drawing  a  line  from  the  front  of  the 
forehead  to  the  front  of  the  upper  jaw,  and  crossing  this  line  by  another 
proceeding  from  the  latter  position  to  the  external  auditory  meatus.  In 
the  white  race,  the  facial  angle  ranges  between  75°  and  85°  ;  in  the  negro, 
between  70°  and  80°.  In  idiots  it  is  65°,  or  even  much  less  ;  and  in  the 
adult  orang-outang  it  is  about  30°. 

In  speaking  of  the  bones  which  compose  the  skull,  eight  were  indicated 
as  belonging  to  the  cranium,  and  fourteen  to  the  face.  The  ethmoid 
bone,  included  in  the  account  of  the  former,  really  contributes  more  to 
the  composition  of  the  latter ;  and  the  face,  as  we  usually  refer  to  it, 
includes  the  forehead  as  formed  by  the  frontal  bone. 

THE  SIDE  OF  THE  SKULL. 

The  Tem/poral  fos'sa2  occupies  a  great  portion  of  the  side  of  the 
skull,  and  is  bounded  above  by  the  temporal  ridge,3  and  below  by  the 
zygomat'ic  arch.  The  former  proceeds  from  the  external  angular 
process  of  the  frontal  bone  upward  and  backward  upon  the  parietal  bone 
to  the  dividing  ridge  between  the  squamous  and  mastoid  portions  of  the 
temporal  bone.  The  tem'poral  surface,  which  gives  origin  to  the  tem- 
poral muscle,  is  formed  by  the  frontal,  sphenoid,  parietal,  and  temporal 
bones ;  and  it  terminates  inferiorly  at  a  ridge  proceeding  from  the  root 

1  Facial  angle  of  Camper ;  angulus  faciei  Camperi.  2  Fossa  temporalis. 

3  Linea  temporalis. 


THE  SKELETON. 


FIG.  64. 


of  the  zygomatic  process  of  the  temporal  bone,  across  the  great  wing  of 
the    sphenoid   bone    to    the 
outer  extremity  of  the  spheno- 
maxillary  foramen. 

The  Zygomat'ic  arch,1  be- 
neath which  passes  the  tem- 
poral muscle  to  its  insertion, 
is  formed  by  the  zygomatic 
process  of  the  temporal  and 
the  malar  bone,  and  gives 
support  to  the  cheek. 

The  Sphe'no-max'illary 
fos'sa2  is  the  space  between 
the  bottom  of  the  great  wing 
and  the  external  pterygoid 
process  of  the  sphenoid  bone, 
and  the  back  part  of  the 

VIEW  OF  THE  RIGHT  SIDE  OF  A  PORTION  OF  THE  FACE  AND  CRA- 

maxillary  bone,  and   NIUM.    1,  frontal  bone;  2,  malar  bone,  a  portion  of  its  zygo 


1S    OCCUpied    by   the    external   matic  process  removed;  3,  zygomatic  process  of  the  temporal 

ft  m  bone  ;  4,  glenoid  tubercle,  and  back  of  it  the  glenoid  cavity  ;  5, 

pterygoid  mUSCle.      At  its  Up-   squanious  portion  of  the  temporal  bone  ;  6,  anterior  inferior 

per  part  anteriorly  is  a  large  an«le  of  the  Parietal  bone  ;  7>  temporal  surface  of  the  frontal 

.     bone  ;  8,  temporal  surface  of  the  great  wing  of  the  sphenoid 

aperture,    the    Sphe  nO-maX  -   bone;    9,  inferior  surface  of  the  great  wing;    10,  external 
fbra'men,3  Which  COm-   pterygoid  process;  11,  internal  pterygoid  process  ;  12,  superior 
maxillary  bone;  13,  ptery  go-maxillary  fossa;  14,  spheno-pala- 


.  ,      ,  ,.          T 

With  the  Orbit.      It 


tine  foramen;  15,  spheno-maxillary  foramen;  16,  oval  fora- 


1S    bounded   by  the   Sphenoid,   men;  17,  spinous  foramen;  18,  infra-orbital  foramen.   Figures 
.-,•,  ,          5-8  occupy  the  fore  part  of  the  temporal  fossa;    the  space 

Superior      maxillary,      malar,    between  9>  10,  and  U,  15,  is  the  spheno-maxillary  fossa. 

and  palate  bones;  and  cor- 

responds to  the  free  communication,  or  rather  continuation,  of  the  tem- 

poral fossa  and  orbit  in  most  of  the  inferior  mammals. 

The  Ptery'go-max'illary  fos'sa4  is  the  deep,  wedge-shaped  fissure,  at 
the  bottom  of  the  former  fossa,  extending  from  the  inner  extremity  of 
the  spheno-maxillary  foramen  downward,  between  the  pterygoid  processes 
of  the  sphenoid  bone,  and  the  superior  maxillary  and  palate  bone.  It  is 
beneath  the  apex  of  the  orbit,  and  has,  opening  from  its  upper  part 
backward,  the  pterygoid  canal  ;  and  inward,  the  spheno-palatine  foramen. 


1  Arcus  zygomaticus  ;    zygoma  ;  pons 
zygomaticus. 

2  Fossa  spheno-maxillaris ;  zygomatic 
fossa. 


3  Foramen   spheno-uiaxillare;    fissura 
orbitalis  inferior,  or  spheno-maxillaris ; 
foramen  lacerum  inferius. 

4  Fossa  pterygo-maxillaris ;  f.  pterygo- 
palatina. 


90 


THE   SKELETON. 


THE  BASE  OF  THE  SKULL. 


FIG.  65. 


VIEW    OF   THE   RIGHT     HALF    OF 
THE  BASE  OF  THE  SKULL.     1,  palate 

plate  of  the  superior  maxillary 
bone ;  2,  palate  plate  of  the  palate 
bone;  3,  vomer ;  4,  internal  ptery- 
goid  process;  5,  external  ptery- 
goid  process ;  6,  pyramidal  process 
of  the  palate  bone ;  7,  under  sur- 
face of  the  great  wing  of  the 
sphenoid  bone;  8,  its  temporal 
surface;  9,  zygomatic  arch;  10, 
zygomatic  process  of  the  malar 
bone;  11,  zygomatic  process  of 
the  temporal  bone;  12,  squamous 
portion  of  the  temporal  bone;  13, 
glenoid  tubercle ;  14,  glenoid  cav- 
ity; 15,  vaginal  process,  its  outer 
border  constituting  the  auditory 
process;  16,  styloid  process;  17. 
external  auditory  meatus;  18, 
mastoid  process;  19,  digastric 
groove ;  20,  basilar  process  of  the 
occipital  bone  co-ossified  with  the 
body  of  the  sphenoid  bone;  21, 
condyle;  22,  occipital  protuber- 
ance ;  23,  superior,  and  24,  inferior 
semicircular  ridges ;  25,  occipital 
foramen ;  26,  incisive  foramen  ; 

27,  posterior   palatine  foramen; 

28,  spheno-maxillary    foramen ; 

29,  posterior  naris ;  30,  oval  fora- 
men ;   31,  spinous  foramen ;  32, 
lacerated  foramen;  33,  Eustachian 

tube ;  34,  carotid  canal ;  35,  jugular  foramen ;  36,  stylo-mastoid  fora- 
men ;  37,  38,  foramina  for  veins. 

and  transverse  pal'ate 

su/tures.3  At  the  fore  part  of  the  middle  suture  is  the  anterior  pal- 
atine fora'men,4  which  communicates  above  with  the  two  naso-palatine 
canals  entering  the  nasal  fossa3.  At  the  posterior  part  of  the  hard 
palate,  on  each  side,  is  the  posterior  pal'atine  fora'men,5  from  which 
coarse  grooves  are  directed  forward  for  the  accommodation  of  the  pal- 
atine nerves  and  blood-vessels. 

The  Gut'teral  region,6  so  named  because  it  forms  the  upper  boundary 


The  Base  of  the 
Skull,  included  in  the 
occipital  and  inferior 
maxillary  outline,  is 
ovate  in  form,  and  in- 
cludes the  palatine,  gut- 
teral,  and  occipital  re- 
gions. 

The  Pal'atine  or 
oral  region1  is  inclosed 
by  the  upper  and  lower 
jaws,  and  is  bounded 
above  by  the  vaulted 
hard  palate.  Its  depth 
ordinarily  is  about  two 
and  a  half  inches,  but 
before  the  protrusion 
of  the  teeth,  and  sub- 
sequent to  their  loss, 
it  is  reduced  to  an  inch 
or  less  in  depth.  The 
hard  pal'ate2  presents 
a  roughened  surface, 
divided  by  the  middle 


1  Regio  palatina :  cavum  oris. 

2  Palatum  durum ;  p.  osseum. 

3  Sutura  palatina  cruciata. 

4  F.  palatinum  anterior  ;  f.  incisivum. 
f.  alveolare  anterius  ;  f.  coecum. 


5  F.   palatinum  posterior,    or    descen- 
dens;    f.  palato-maxillare ;  f.    alveolare 
postering. 

6  Regio  gutteralis. 


THE   SKELETON.  91 

of  the  pharynx  or  throat,  has  the  posterior  nares  opening  into  it  in  front, 
and  is  limited  behind  by  the  occipital  foramen  and  condyles.  On  each 
side  are  the  pterygoid  processes,  and  above,  it  is  bounded  by  the  basilar 
process  of  the  occipital  bone  and  the  body  of  the  sphenoid  bone. 

The  Occipital  region  includes  that  part  of  the  base  of  the  skull  pos- 
terior to  the  occipital  foramen  and  condyles. 


THE  ORBITS. 

The  OrVits1  are  quadrately  pyramidal  cavities  situated  beneath  the 
anterior  part  of  the  cranium,  with  their  axes  directed  forward  and 
outward. 

The  apex  of  each  orbit  corresponds  with  the  optic  foramen,  and  the 
base  forms  the  orVital  entrance,2  This  is  situated  beneath  the  forehead, 
and  is  transversely  quadrate-oval,  with  a  slight  obliquity  from  the  median 
line  downward,  and  a  direction  forward  and  a  little  outward. 

The  roof  of  the  orbit  is  vaulted,  and  is  formed  by  the  orbital  plate  of 
the  frontal  bone  and  the  lesser  wing  of  the  sphenoid  bone.  The  floor  is 
slightly  depressed  below  the  infra-orbital  margin,  and  is  formed  by  the 
orbital  plate  of  the  superior  maxillary  bone  and  the  orbital  process  of  the 
palate  bone.  The  inner  wall  is  nearly  vertical  and  parallel  with  that  of 
the  other  orbit,  and  is  formed  by  the  nasal  process  of  the  superior  max- 
illary bone,  the  lachrymal  bone,  the  orbital  plate  of  the  ethmoid  bone, 
and  the  body  of  the  sphenoid  bone.  The  outer  wall  is  also  nearly  vertical, 
but  is  directed  obliquely  outward ;  and  it  is  composed  of  the  orbital  plate 
of  the  great  wing  of  the  sphenoid  bone  and  that  of  the  malar  bone. 

At  the  bottom  or  apex  of  the  orbit  are  the  optic  and  sphenoidal  fora- 
mina, already  described,  and  between  the  outer  wall  and  floor  is  the 
spheno-maxillary  foramen,  also  previously  described. 

At  the  anterior  part  of  the  inner  wall  of  the  orbit  is  the  lach/rymo- 
na'sal  duct'.3  Commencing  as  a  fossa4  or  groove  between  the  nasal  pro- 
cess of  the  superior  maxillary  and  lachrymal  bones,  by  the  addition  of  a 
process  of  the  turbinated  bone,  its  lower  half  forms  a  complete  tube. 
It  descends  with  a  slight  inclination  backward,  and  terminates  at  the 
anterior  part  of  the  inferior  meatus  of  the  nasal  fossa. 

At  the  upper  border  of  the  inner  wall  of  the  orbit,  in  the  suture 


1  Orbitao;  trochiae  ;  conchi;  cavitates,  3  Ductus  or  canalis  lachrymo-nasalis, 
or  fovese,  or  pelviculae  oculorum ;   orb-       or  naso-lachrymalis  ;  ductus  ad  nasum  : 
itarfossoe;  orbitar  cavities.                             lachrymal  duct;  nasal  duct;   ductus  na- 

2  Apertura  orbitalis.  sails  orbitse. 

4  Fossa  lachrymalis. 


92 


THE   SKELETON. 


between  the  ethmoid  and  frontal  bones,  are  the  anterior  and  posterior 
ethmoid'al  fora'mina,1  for  the  transmission  of  a  nerve  and  an  artery. 


FIG.  66. 


THE  NASAL  CAVITIES. 

The  Na'sal  cavities  or  fos'sae2  are  two  complicated  spaces  separated 
by  a  thin  vertical  partition,  the  os'seous  na'sal  sep'tum.3  They  open  on 
the  front  of  the  face  by  the  anterior  na'sal  or'ifice,  and  communicate 
posteriorly  with  the  gutteral  region  by  the  posterior  na'sal  or'ifices  or 
na'res.  Communicating  with  them  are  the  frontal,  ethmoidal,  sphenoidal, 
and  maxillary  sinuses,  which  are  accessory  chambers. 

The  height  and  depth  of  each  nasal  cavity  are  about  two  inches  ;  the 
greatest  width,  which  is  below  the  turbinated  bone,  is  about  half  an 
inch. 

The  anterior  na'sal  or'ifice*  is  pyriform,  and  is  bounded  by  the  supe- 

rior maxillary  and  na- 
sal bones.  Its  border  is 
thin  and  sharp  ;  in  the 
negro,  however,  it  is 
rounded  off  at  the  bot- 
tom. From  the  middle 
of  its  base,  the  na'sal 
spine5  projects,  for  the 
attachment  of  the  column 
of  the  nose. 

The  posterior  na'sal 
or'ifices6  are  quadrate 
apertures  separated  by 
the  vomer,  and,  in  addi- 
tion to  the  latter,  are 
bounded  by  the  body  and 
internal  pterygoid  proc- 


esses 

VERTICAL  SECTION  OF  THE  FACE,  exhibiting  the  osseous  nasal  sep- 
turn.  1,  frontal  bone;  2,  frontal  sinus;  3,  nasal  spine  of  the  frontal  bone 
bone;  4,  nasal  bone;  5,  nasal  spine  of  the  superior  maxillary  bone; 
6,  nasal  process  of  the  same  bone  ;  7,  border  of  the  palate  plate  of 
the  same;  8,  incisive  foramen;  9,  left  posterior  naris;  10,  palate  plate 
of  the  palate  bone  ;  11,  nasal  plate  of  the  ethmoid  bone  ;  12,  ethmoidal 
crest;  13,  vomer;  14,  left  turbinated  bone;  15,  sphenoidal  sinus;  16, 
internal  pterygoid  process  ;  17,  external  pterygoid  process. 


of    the    sphenoid 

r 
and       the       palate 


The  OS  SGOUS  na  Sal 
coYj'fmn.  IS  formed  bv  the 
nasal  plate  Of  the  6th- 


1  F.  ethmoidale  anterius  et  posterius  ; 
f.  orbitale  ant.  et  post. 

2  Cavi  narium  ;  nares  internae. 

3  Septum  narium  osseum. 


*  Apertura  narium  anterior. 

5  Anterior  nasal  spine. 

6  Posterior    nares ;    aperturae  narium 
posteriores. 


THE  SKELETON. 


93 


FIG.  67. 


moid  bone  and  the  vomer,  which  have  between  them  anteriorly  a  deep 
angular  notch  for  the  reception  of  the  cartilaginous  septum.  Frequently 
the  nasal  septum  is  bent  to  one  side,  thus  increasing  the  width  of  one 
cavity  at  the  expense  of  the  other. 

The  roof  of  the  nasal  cavities  is  antero-posteriorly  concave,  and  is 
narrower  and  longer  than  any  other  portion.  It  is  formed  by  the  nasal 
bones,  the  nasal  spine  of  the  frontal  bone,  the  cribriform  plate  of  the 
ethmoid  bone,  and  the  body  of  the  sphenoid  bone. 

The  floor  of  the  nasal  cavities  is  a  little  depressed  below  the  level  of 
the  base  of  the  anterior 
nasal  orifice ;  and  is 
formed  by  the  palate 
plates  of  the  maxillary 
and  palate  bones. 

The  outer  wall  is  the 
most  complicated  portion 
of  the  nasal  cavities. 
From  it  project  inward 
and  downward,  like  three 
scrolls,  the  turbinated 
processes  of  the  ethmoid 
bone  and  the  turbinated 
bone ;  and  below  these 
are  situated  the  na'sal 
mea'tuses.1 

The  superior  mea'tus 
is  the  shortest,  is  situated 


VIEW  OF    THE   OUTER  WALL  OF  THE   RIGHT   NASAL   FOSSA.      1,  frontal 


,,  bone ;  2,  its  orbital  plate ;  3,  its  nasal  spine ;  4,  nasal  bone ;  5,  eth- 
'  DaCK  part  OI   moid  bone;  6j  itg  upper  turbinate(i  pr0cess;  7,  its  lower  turbinated 
each     Cavity,     and    is    di-    process  ;  8,  turbinated  bone;  9,  process  of  the  lachrymal  bone,  within 
,     -,         -,-,•          i         -,  the  position  of  which  is  the  lachrymo-nasal  duct ;  10,  nasal  spine  of 

rected    obliquely   down-  th/superior  maxillary  bone.  £  naso_palati.ne  canal;  12,  palate 

Ward  and  backward  tO  plate  of  the  superior  maxillary  bone;  13,  nasal  process  of  the  latter; 
the  UDDer  Dart  Of  the  14>  external  PteiTg°id  process;  15,  internal  pterygoid  process;  16, 

nasal  plate  of  the  palate  bone ;  17,  its  palate  plate ;  18,  posterior  pal- 

Corresponding  posterior  atine  foramen ;  19,  superior  meatus  of  the  nose ;  20,  middle  meatus ; 
nasal  Orifice  Into  it  21,  inferior  meatus ;  22,  frontal  sinus;  23,  sphenoidal  sinus;  24,  its 

communication  with  the  upper  back  part  of  the  nose ;  25,  spheno- 
the  posterior  and  middle  palatine  foramen ;  26,  orifice  of  the  maxillary  sinus. 

ethmoidal  sinuses  open ; 

and  above  its  posterior  extremity,  the  sphenoidal  sinus  communicates 

with  the  nose. 

The  middle  meatus  is  situated  between  the  ethmoid  and  turbinated 
bones  along  the  middle  of  the  nasal  cavity.      Into  it  open  the  anterior 


1  Meatus  narium. 


94  THE   SKELETON. 

ethmoidal  and  frontal  sinuses  and  the  maxillary  sinus.  The  orifice  of  the 
latter  is  much  reduced  in  size  compared  with  its  condition  in  the  isolated 
maxillary  bone ;  the  ethmoid,  palate,  turbinated,  and  lachrymal  bones 
all  contributing  to  its  diminution. 

The  inferior  mea'tus,  situated  below  the  turbinated  bone,  is  trans- 
verse in  its  direction  from  before  backward  ;  and  it  has  communicating 
with  its  anterior  part,  the  lachrymo-nasal  duct. 

DEVELOPMENT  OF  THE  FACE. 

In  all  mammals  below  man,  that  portion  of  the  superior  maxillary  bone 
•which  supports  the  incisor  teeth  is  separated  from  the  principal  portion, 
and  is  known  as  the  intermaxillary  bone.  It  may  be  observed  in  the 
skull  of  any  domestic  animal.  As  a  distinct  piece,  it  is  obscurely  visible 
in  the  human  embryo  as  late  as  the  third  month,  and  may  be  detached 
from  the  superior  maxillary  bone.  It  soon  becomes  co-ossified  with 
the  latter,  and  its  line  of  separation  is  distinguishable  subsequently 
only  for  a  short  distance  transversely  outward  from  the  incisive  fora- 
men. Occasionally,  as  in  some  cases  of  hare-lip,  the  intermaxillary 
bone  remains  permanently  distinct.  To  the  main  portion  of  the  maxil- 
lary bone,  the  author  has  not  been  able  to  detect  more  than  a  single 
point  of  ossification,  from  which  the  bony  rays  shoot  upward,  backward, 
and  outward. 

The  palate  bone  is  developed  from  a  single  ossific  point,  commencing 
at  the  angle  of  conjunction  of  the  vertical  and  horizontal  portions. 

The  lachrymal,  nasal,  turbinated,  and  malar  bones,  and  the  vomer,  are 
each  developed  from  one  centre  of  ossification. 

In  the  development  of  the  inferior,  maxillary  bone,  each  half  appears 
to  originate  in  a  single  ossific  point,  which  commences  before  any  other 
in  the  skeleton,  except  that  of  the  clavicle.  At  birth  the  lower  jaw  con- 
sists of  two  halves,  united  at  the  symphysis  by  fibro-cartilage,  but  which, 
during  the  first  year,  subsequently  co-ossify. 

CHANGES  OF  THE  SKULL  AT  DIFFERENT  PERIODS  OF  LIFE. 

In  the  embryo  and  early  foetus  the  skull  has  a  spheroidal  figure,  with 
a  comparatively  small  conical  prominence  corresponding  to  the  face.  At 
birth,  and  for  some  time  subsequently,  the  cranium  is  still  more  spher- 
oidal than  afterwards,  and  at  this  early  period  is  much  larger  in  com- 
parison with  the  face  than  at  maturity.  The  facial  angle  also  is  greater 
than  it  is  at  a  later  period. 

The  skull  is  composed  of  a  greater  number  of  pieces  at  birth  than 


THE   SKELETON.  95 

afterwards,  as  already  indicated  in  the  account  of  the  individual  bones. 
The  texture  of  these,  due  to  their  greater  proportion  of  bone  carti- 
lage, is  more  flexible,  and  they  are  rather  disposed  to  bend  than  to  break. 
The  bones  likewise  are  more  readily  movable  upon  one  another,  so  that 
from  this  and  the  preceding  circumstance,  the  head  in  infancy  is  readily 
modified  in  shape  artificially,  as  instanced  in  the  change  of  form  produced 
in  the  cranium,  customary  among  the  Flat-head  Indians,  and  other  savage 
tribes. 

In  the  infant  skull,  the  bones  of  the  vault  of  the  cranium  are  more 
conical  than  concavo-convex,  as  they  afterwards  become.  The  greatest 
transverse  diameter  of  the  skull  is  at  the  parietal  protuberances ;  but 
later,  is  at  the  temporal  fossae.  The  latter  are  proportionately  small, 
in  accordance  with  the  moderate  development  of  the  temporal  muscles, 
which  are  not  yet  required  for  mastication.  The  face  is  low,  and  situated 
entirely  beneath  the  cranium.  The  nasal  cavities  are  small,  and  the 
various  sinuses  communicating  with  them  only  begin  to  be  developed. 
The  mouth  or  palatine  region  in  vertical  depth  is  not  more  than  half  an 
inch  ;  and  the  rami  of  the  lower  jaw  project  comparatively  little  above 
its  body,  and  are  more  oblique  than  afterwards.  As  the  child  grows, 
the  bones  of  the  skull  acquire  greater  hardness,  become  thicker,  and 
gradually  develop  their  spongy  substance  and  their  sinuses. 

With  the  development  of  the  teeth  and  alveolar  processes,  and  the 
protrusion  of  the  former,  the  face  becomes  more  prominent  and  deeper, 
the  facial  angle  declines,  and  the  spaces  occupied  by  the  masticating 
muscles  enlarge.  The  rami  of  the  lower  jaw  lengthen  downward,  and 
become  less  oblique ;  and  the  mouth  increases  to  two  and  a  half 
inches  of  vertical  depth.  With  the  advance  of  the  face,  there  is  also  a 
recession  of  the  cranium;  and  from  the  development  of  the  frontal 
sinuses,  the  superciliary  ridges  become  the  most  prominent  portion  of  the 
forehead,  instead  of  the  frontal  protuberances  as  in  infancy. 

From  puberty  to  adult  age,  but  little  change  occurs  in  the  skull,  except 
a  comparatively  slight  and  very  gradual  increase  in  size  and  strength. 
At  maturity  the  sutures  gradually  disappear ;  and  in  old  age  a  sort  of 
retrograde  metamorphosis  occurs.  The  bones  of  the  skull  become 
thinner  and  more  brittle,  and  the  spongy  substance  decreases,  though  the 
sinuses  enlarge.  With  a  diminution  in  quantity  of  the  brain,  the  cranium 
undergoes  an  actual  reduction  in  size.  The  teeth  drop  out,  and  the  alve- 
olar borders  of  the  jaws  disappear,  reducing  the  depth  of  the  mouth 
almost  to  the  condition  of  that  in  infancy.  In  consequence  of  these 
changes,  the  face  loses  much  of  its  vertical  extent,  and  the  facial  angle 
is  increased.  As  the  body  of  the  lower  jaw  forms  a  much  larger 


96 


THE  SKELETON. 


FIG.  68. 


arch  than  the  upper  jaw,  it  mounts  upon  and  incloses  the  latter,  thus 
bringing  the  prominent  chin  just  beneath  the  nose,  as  so  strikingly 
observed  in  the  aged. 

THE  HYOID  BONE. 

The  Hy'oid  bone1  is  situated  in  the  front  of  the  neck,  at  the  root  of 
the  tongue,  and  is  readily  felt  just  above  the  larynx.  It  consists  of  a 
median  symmetrical  body,  with  a  pair  of  horns  on  each  side. 

The  body2  is  the  middle  piece  in  front,  and  is  quadrate  in  outline. 
Anteriorly  it  is  convex  and  impressed  on  each 
side  by  muscles,  and  posteriorly  is  concave. 

The  greater  horns3  project  backward  from 
the  ends  of  the  body;  and  are  comparatively 
long,  thin  processes  ending  in  a  tubercle.  The 
lesser  horns,4  usually  in  a  cartilaginous  condi- 
tion until  late  in  life,  are  conical,  and  project 
upward  and  backward  from  the  junction  of  the 
body  with  the  greater  horns. 
The  lesser  horns  connect  the  hyoid  bone  with  the  styloid  process  of 
the  temporal  bone,  by  means  of  a  long,  narrow,  fibrous  cord,  the  sty'lo- 
hy'oid  liga'ment,5  Generally  they  are  only  two  or  three  lines  long,  and 
often  vary  in  length  and  degree  of  ossification  on  the  two  sides.  Some- 
times ossification  extends  from  them  up  the  stylo-hyoid  ligament,  and 
rarely,  its  entire  length. 


HYOID  BOXE.     1,  body;  2, 
greater  horn ;  3,  lesser  horn. 


THE  TRUNK. 

That  division  of  the  skeleton  called  the  trunk6  is  composed  of  the 
vertebral  column,  the  ribs,  the  sternum,  and  the  hip  bones.  Its  upper 
extremity  forms  the  bony  axis  of  the  neck ;  below  this  is  the  thorax  or 
chest ;  then  follows  the  axis  of  the  loins ;  and  the  lower  part  of  the 
trunk  forms  the  pelvis. 


1  Os  hyoides  ;  os  linguae,  or  lingualc  ; 
os  ypsiloides ;  os  gutteris,  or  gutterale  ; 
os  bicorne  ;  os  lambdoides. 

2  Basis ;  ossiculum  medium  hyoidis. 

3  Cornua  majora;  branches;  rami. 


*  Cornua  minora  ;  corpuscula,  or  grana 
triticea ;  cornicula ;  ossa  pisiformia  lin- 
gualia ;  styloid  cornua. 

5  Ligamentum  stylo-hyoideum. 

6  Truncus. 


THE  SKELETON. 


97 


THE  VERTEBRAL  COLUMN. 

The  Vert'ebral  column1  is  the  axis  of  sup- 
port of  the  body,  and  is  situated  along  the 
middle  line  of  the  trunk  posteriorly.  It  is 
composed  of  twenty-nine  symmetrical  pieces, 
named  vert/ebrae,2  which  are  divided  into 
twenty-four  true  and  five  false  vertebrae. 

In  front,  the  vertebral  column  is  composed 
of  a  series  of  half  cylindroid  segments  con- 
joined by  fibro-cartilage ;  posteriorly,  of  a  series 
of  arches  supporting  processes  for  mutual  ar- 
ticulation, and  others  for  muscular  attachment. 
From  the  elongated  spine-like  character  of  its 
posterior  median  processes,  the  entire  column 
is  ordinarily  named  the  spine.3 


FIG.  69. 


THE  TRUE  VERTEBRAE. 

The  True  vert'ebrae,4  twenty-four  in  number, 
extend  from  the  skull  to  the  pelvis,  and  gradu- 
ally increase  from  the  first  to  the  last,  which 
rests  on  the  sacrum.  From  their  relative  po- 
sition in  the  trunk  they  are  divided  into  cer- 
vical or  neck  vertebrae,  dorsal  or  thoracic  ver- 
tebrae, and  lumbar  vertebrae. 

The  true  vertebrae  are  composed  of  a  body 
and  an  arch  supporting  seven  processes. 

The  body5  is  at  the  fore  part,  and  usually 
possesses  the  form  of  a  transverse  segment  of 
a  half  cylinder,  concave  posteriorly,  and  con- 
stricted at  the  front  and  sides.  Its  broad  sur- 
face above  and  below  is  generally  flat,  with  a 
slightly  elevated  border;  and  is  conjoined  with 
the  contiguous  vertebral  body  by  means  of  a  8  to  iMorsai  vertebra;  20  to  24, 

lumbar  vertebrae :  25,  sacrum;  26, 

plate  of  nbro-cartilage.  coccyx. 


THE  VERTEBRAL  COLUMN,  lateral 
view;  exhibiting  the  curvatures, 
1  to  24,  true  vertebrae;  25,  26,  false 
vertebrae;  1  to  1.  cervical  vertebrae ; 


1  Columna  vertebralis;  spinal  column; 
columna  spinalis ;  columna  dorsi ;  spine; 
spina  dorsi;  back  bone;  rachis ;  carina; 
dorsum;  tergum;  notos;  acnestis ; 
acantha;  compages  vertebrarum ;  sacra 
fistula;  hiera  syrinx. 


2  Spondyli ;  spondles;  whetle  bones. 

3  Spina. 

4  Vertebrae  veroe. 

5  Corpus  vertebrae;  centrum. 


98 


THE   SKELETON. 


FIG.  70. 


SIDE  VIEW  OF  A  DOBSAL  VERTEBRA.  1,  body ;  2, 
articular  facets  for  ribs ;  3,  arch  ;  4,  5,  interverte- 
bral  notcb.es;  6,  spinous  process;  7,  transverse 
process;  8,  9,  articular  processes. 


The  arch1  is  attached  to  the  sides  of  the  body  posteriorly  by  narrow 
ped/icles,2  and  the  passage  through  it  is  the  spi'nal  fora'men,3  forming 

part  of  the  spinal  canal  for  contain- 
ing the  spinal  cord.  In  form  the 
arch  is  angular,  and  its  sides  ex- 
pand below ;  so  that  in  the  verte- 
bral column  the  arches  together 
present  a  somewhat  imbricated  ap- 
pearance. 

From  the  summit  of  the  arch 
posteriorly  projects  the  spi'nous 
proc'ess,4  and  from  each  side,  the 
trans'verse  proc'ess,5  all  of  which 
serve  as  points  of  attachment  for 
muscles.  Above  and  below,  the 
arch  supports  a  pair  of  artic'ular 
proc'esses,6  which  present  smooth 
discoidal  facets  for  articulation  with  those  of  the  contiguous  vertebra?. 

Between  the  position  of  the  articular  and  spinous  processes,  the  arch 
is  formed  of  a  pair  of  shelving  plates,7  of  which  the  upper  border 
behind  and  the  lower  border  in  front  are  roughened  for  the  attachment 
of  the  elastic  yellow  ligaments. 

Above  and  below  the  pedicles  of  the  arch,  and  between  the  articular 
processes  and  body,  are  the  intervert/ebral  notches,  of  which  the  infe- 
rior pair  is  generally  the  deeper.  By  the  approximation  of  the  notches 
of  the  contiguous  vertebra  they  form  the  intervert'ebral  fora'mina,8 
for  the  transmission  of  the  spinal  nerves  and  blood-vessels. 

In  structure,  the  body  of  the  vertebra?  is  composed  of  a  mass  of 
spongy  substance  covered  with  a  thin  layer  of  compact  substance,  which 
is  perforated  with  numerous  comparatively  large  nutritious  or  vascular 
foramina.  At  the  middle  of  the  body  posteriorly  there  are  two  of  these 
foramina  particularly  conspicuous,  which  communicate  with  channels  for 
conducting  veins  from  the  spongy  substance  to  the  vertebral  sinuses. 
The  vertebral  arch,  together  with  its  processes,  requiring  greater  strength 


1  Arcus    vertebrae;    vertebral     arch; 
neural  nrch. 

2  Neurapophyses. 

3  Foramen  spinale,  or  vertebrale  ;  ver- 
tebral foramen. 

4  Processus  spinosus;  neural  spine. 

5  P.  trans.versus  ;  diapophysis. 


6  P.  articulares;    oblique     processes  ; 
p.  ascendentes  et  descendentes;    zyga- 
pophyses. 

7  Veriebral  plates;  laminae  ;  neurapo- 
physes. 

8  F.  intervertebralia  ;    f.   vertebralia; 
f.  conjugata. 


THE   SKELETON.  99 

than  the  body,  have  a  predominance  of  compact  substance  composing 
them. 

The  characters,  thus  given  of  the  true  vertebrae,  are  modified  in  the 
three  regions  to  which  we  have  referred  ;  so  that  the  cervical,  dorsal,  and 
lumbar  vertebrae  will  now  require  a  special  description.  In  each  region, 
however,  the  characters  are  not  constant  for  all  the  vertebrae,  as  we  find 
those  of  contiguous  regions  assuming  more  or  less  the  appearance  of 
one  another ;  and  in  several  instances  they  are  much  modified,  so  as  to 
be  adapted  to  some  special  function,  as  in  the  case  of  the  upper  pair  of 
the  neck. 

THE  CERVICAL  VERTEBRA. 

The  Cer'vical  vert'ebrae1  are  seven  in  number,  and  form  the  bony  axis 
of  the  neck,  extending  from  the  skull  to  the 
thorax.      The   most    striking   peculiarity,   by  FIG.  71. 

which  they  may  be  distinguished  from  those  of 
the  other  regions  of  the  trunk,  is  the  large 
foramen  in  the  transverse  processes. 

The  body  is  widest  transversely,  and  this 
disposition  increases  from  the  first  to  the  last 
of  the  series.  Its  upper  surface  is  rendered 
transversely  concave  from  the  elevation  of  the 
lateral  borders;  and  its  lower  surface  is  in  a 
less  degree  concave  in  the  opposite  direction  UPPER  VIEW  OF  A  CERVICAL  VERTE- 
from  the  prolongation  of  the  anterior  and  pos-  BRA»  from  tho  naiddle  of  the  series- 

.  1,  body;  2,  3,  arch;  4,  spinous  proc- 

terior   borders.     From   this  arrangement  the  ess;  5,  transverse  process;  6,  its  fo- 

COntlgUOUS    bodies    interlock,    thus    affording    a    ramen;  7,  superior  articular  process; 

8,  inferior  articular  process;  9,  ele- 
prOVlSlOn    against   dislocation  where  the  Verte-    vated  lateral  border  of  the  body. 

brae  are  smallest. 

The  arch  is  less  deep,  but  wider  than  in  the  dorsal  or  lumbar  vertebrae ; 
and  the  spinal  foramen  is  trilateral,  with  rounded  angles,  and  larger  than 
in  the  other  true  vertebrae.  The  upper  and  lower  intervertebral  notches 
are  nearly  equal  in  size. 

The  spinous  process  is  comparatively  short,  and  is  bifid  at  the 
extremity.  The  transverse  processes  are  also  comparatively  short,  and 
they  consist  of  two  portions.  The  posterior  portion,2  springing  from 
the  pedicle  of  the  vertebral  arch,  corresponds  with  the  transverse  processes 
of  the  dorsal  vertebrae,  while  the  anterior  portion  corresponds  with  the  ribs.3 
The  two  portions  being  conjoined  by  an  isthmus,  a  foramen4  is  formed, 

1  Vertebras  colli ;  v.  cervicis.  3  Parapophysis. 

2  Diapophysis.  *  F.  transversarium ;  f.  vertebrate. 


Carbon, 

100  THE   SKELETON. 

which,  in  the  case  of  the  upper  six  vertebrae  of  the  neck,  transmits  the 
vertebral  artery. 

The  upper  articular  processes  have  their  facets  directed  obliquely  back- 
ward and  upward ;  the  lower  ones,  downward  and  forward. 

The  description  thus  given  of  the  cervical  vertebrae  applies  especially 
to  those  from  the  third  to  the  sixth  inclusive ;  the  remaining  three  pos- 
sess peculiarities  requiring  special  notice. 

The  first  cervical  vertebra  is  named  the  Atlas,1  from  its  supporting 
the  head.  It  is  an  irregular  ring,  and  is  broader  than  any  other  of  the 
vertebrae  of  the  neck.  The  large  space  included  by  the  ring  is  divided 
by  the  transverse  ligament  into  two  parts,  of  which  that  anterior  is  the 
smallest,  and  is  occupied  by  the  pivot-like  odontoid  process  of  the  second 
vertebra ;  the  posterior  portion  is  the  true  spinal  foramen. 

Anteriorly,  the  atlas  presents  a  short  transverse  bridge,  with  a  tubercle 

in  front,  and  a  smooth  articular 
facet  behind,  which  moves  on  the 
odontoid  process. 

The  arch  of  the  atlas  is  rounded, 
and  its  rudimental  spinous  process 
is  in  the  form  of  a  small  tuberosity. 
The  transverse  process  is  much 
prolonged  beyond  that  of  the  other 
UPPER  VIEW  OF  THE  ATLAS,  i,  anterior  tubercle;  cervical  vertebrae,  and  ends  in  a 

2,  articular  facet  for  the  odontoid  process;  3,  arch,  ,     .,        , 

with  its  rudimental  spinous  process;  4,  groove  for        founded  tuberOSlty. 

the  vertebral  artery ;  5,  transverse  process ;  6,  its  The     Upper     articular     prOCCSSeS 

form  elliptical  concavities  inclining 
inwardly,  and  having  their  long 
diameter  directed  forward  and  inward.  They  articulate  with  the  occip- 
ital condyles,  and  are  the  centre  of  the  backward  and  forward  motion  of 
the  head.  The  lower  articular  processes  have  oval,  slightly  depressed 
facets,  directed  downward  and  inward. 

The  portions  of  the  atlas  forming  the  articular  processes  are  the 
thickest  and  strongest  of  ths  bone ;  and  they  are  adapted  to  sustain  the 
pressure  of  the  skull,  which  is  subsequently  transmitted,  through  the 
obliquity  of  the  inferior  articular  processes,  to  the  body  of  the  second 
cervical  vertebra,  and  thence  through  all  the  other  vertebral  bodies. 

Between  the  position  of  the  upper  and  lower  articular  processes  intern- 
ally, is  a  tuberosity,  for  the  attachment  of  the  transverse  ligament,  which 
retains  the  odontoid  process  in  its  place. 

1  Atlantion ;  astragalus. 


THE  SKELETON.  101 

The  intervertebral  notches  of  the  atlas  are  behind  the  articular  processes, 
those  below  being  the  smaller.  The  upper  ones  are  continuous  with  a 
groove  from  the  foramen  of  the  transverse  process,  and  transmit  the  ver- 
tebral arteries  in  their  course  to  the  occipital  foramen.  Sometimes 
these  upper  notches  are  converted  by  a  bridge  of  bone  into  foramina. 

The  second  cervical  vertebra  is  called  the  Ax'is,1  from  its  supporting 
the  pivot  upon  which  the  atlas  and  the  skull 
together  rotate.  FlG-  73< 

The  body  of  the  axis  presents  a  median 
prominence  in.  front,  and  its  upper  part  is  pro- 
longed into  the  pivot-like  odontoid  proc'ess,2 
which  projects  within  the  circle  of  the  atlas. 
The  process  is  conical,  has  a  smooth  facet  in 
front  to  articulate  with  the  bridge  of  the  atlas, 
and  another  behind,  against  which  the  trans-  SIDE  VIEW  OF  THE  AXIS,  i,  body; 
verse  ligament  moves.  The  summit  and  sides  ^n^?T^±,t 

are    also    impressed    by    the    attachment    Of    the    transverse  process,  with  its  foramen; 

ligaments  Which    moderate    the    rotation    Of  the    7,  8,  superior  and  inferior  articular 

processes. 

head. 

The  arch  of  the  axis  is  more  robust  than  in  any  other  of  the  cervical 
vertebrae.  The  spinous  process  is  comparatively  very  strong ;  and  it 
has  depressed  sides,  a  deep  groove  below,  and  a  cleft  extremity.  The 
transverse  process  is  the  shortest  in  the  cervical  series,  and  its  foramen 
ascends  at  first  beneath  the  upper  articular  processes,  and  then  turns 
abruptly  outward  and  backward. 

The  upper  articular  processes  are  oval  in  form  and  slightly  convex, 
and  rest  obliquely  upon  the  sides  of  the  body  and  the  pedicles.  They 
are  the  circle  of  the  rotary  movements  of  the  head,  while  the  odontoid 
process  is  the  centre. 

The  upper  intervertebral  notches  are  obsolete ;  while  those  below,  and 
other  parts  of  the  bone  in  this  position,  correspond  with  the  condition 
of  the  other  vertebra?  of  the  neck. 

The  last  cervical  vertebra3  partakes  strongly  of  the  characters  of  the 
dorsal  series,  and  is  particularly  remarkable  for  the  length  of  its  spinous 
process,  which  is  tuberous  at  the  end,  instead  of  being  cleft  as  in  the 
others. 

1  Vertebra     dentata;      epistropheus ;  2  P.  odontoideus,    or  odontoides;    p. 

axon ;  maschalista.  dentatus ;  p.  dentiformis ;  p.  pyrenoides. 

3  V.  prominens. 


102  THE  SKELETON. 


THE  DORSAL  VERTEBRAE. 

The  Dor'sal  vert'ebrse,1  twelve  in  number,  form  the  bony  axis  of  the 
thorax,  and  extend  from  the  neck  to  the  loins. 

The  most  characteristic  marks  by  which  they  may  be  distinguished 
from  other  vertebra  are  the  articular  facets  for  the  ribs. 

The  bodies  decrease  in  breadth  from  the  first  to  the  third,  then  are 

nearly  uniform  in  this  respect  to 

FlG-  74-  the  fifth,  and  afterwards  gradually 

increase  to  the  last.  They  are 
more  demi-cylindroid  in  form  than 
either  those  of  the  neck  or  loins. 
Their  upper  and  lower  surfaces  are 
flat. 

The  arches  are  smaller  and 
stronger  than  in  the  cervical  verte- 
bra. The  spinal  foramen  is  nearly 
circular,  and  is  smaller  than  in  the 

°r 


SIDE  VIEW  OP  A  DORSAL  VERTEBRA.    1,  body  ;  2, 

facets  for  ribs;  3,  arch;  4,  5,  interverte-  The  lower  interVCrtebral  notches 


are  much  lareer  than  the 

ones. 

The  spinous  processes  are  long  and  narrow,  are  trilateral,  and  have  a 
tuberous  extremity.  They  are  directed  backward  and  downward,  suc- 
cessively increasing  in  the  latter  inclination  to  the  lower  ones  of  the 
series.  The  transverse  processes2  are  long  and  strong,  and  terminate 
in  a  thick  tuberosity.  They  are  directed  outward,  with  a  successively 
increasing  inclination  backward.  The  articular  processes  are  nearly  ver- 
tical ;  those  above  being  directed  backward,  those  below  forward. 

The  articular  facets  for  the  ribs  are  situated  one  at  the  upper  and 
lower  margin  of  the  body,  on  each  side  posteriorly,  and  another  in  front 
of  the  extremity  of  the  transverse  processes.  The  facets,  at  the  sides 
of  the  bodies  of  contiguous  vertebrae,  together  form  pits,3  for  the  articu- 
lation of  the  head  of  the  ribs.  The  facet  of  the  transverse  process  articu- 
lates with  the  tubercle  of  the  ribs. 

The  bodies  of  the  first  and  last  two  dorsal  vertebra  present  each  a 
complete  articular  facet  for  the  heads  of  the  corresponding  ribs. 


V.  dorsales;  v.  thoracis  ;  thoracic  vertebrae.  2  Diapopliyses. 

3  Foveae  articulares. 


THE   SKELETON.  103 


THE  LUMBAR  VERTEBRAE. 

The  Lum'bar  vert'ebrae,1  five  in  number,  form  the  bony  axis  of  the 
loins,  and  extend  from  the  thorax  to  the  pelvis.  They  are  the  largest 
of  the  true  vertebrae,  and  are  readily  distinguished  from  the  others  by  the 
absence  of  a  foramen  in  the  transverse  processes  and  articular  facets  for 
ribs. 

The  bodies  are  oval  in  transverse  section,  and  successively  increase 
in  size  to  the  last.     As  in  the  dorsal 
series,  their  upper  and  lower  surface 
is  flat.     The  arches  are  strong,  and 
increase  in  width  from  first  to  last. 

The  spinal  foramen  is  large 
and  trilateral.  The  intervertebral 
notches  are  large,  and  nearly  equal 
in  size  above  and  below. 

The   spinous   process    forms   a        SlDE  VIEW  OF  A  1UMBAR  V£RTEBRA.  i,  body;  2. 

Strong      Vertical      plate      projecting        side  of  the  arch;  3,4,  intervertebral  notches;  5, 
,.  .  ,,.    ,  spinous  process;  6,  transverse  process;  7,  8,  artic- 

backward  and  ending  in  a  thick-     ular  proce8se8. 
ened  extremity. 

The  transverse  processes2  are  narrow,  directed  outwardly,  and  suc- 
cessively increase  in  length  to  the  middle  of  the  series,  and  then  dimmish 
to  the  last.  They  represent  ribs  ;  while  the  part  corresponding  with  the 
transverse  processes  of  the  dorsal  vertebra  is  a  tubercle  projecting  from 
the  outer  side  of  the  upper  articular  process. 

The  articular  processes  are  vertical ;  the  upper  ones  being  directed 
toward,  while  the  lower  ones  are  directed  from  each  other,  by  which 
arrangement  those  of  the  contiguous  vertebrae  interlock,  and  thus  aid  in 
maintaining  the  articular  integrity  of  the  column,  where  it  has  no  lateral 
support  as  in  the  thorax. 

THE  FALSE  VERTEBRAE. 

The  False  vert'ebrae3  are  so  called  because  they  consist  of  nine  seg- 
ments corresponding  with  the  true  vertebrae,  which  in  the  mature  condi- 
tion are  co-ossified  into  comparatively  few  pieces.  The  upper  five  pieces, 
co-ossified,  constitute  the  sacrum  ;  the  lower  four  pieces  form  the  coccyx. 

1  V.  lumbales;  vertebra}  of  the  loins.  2  Purapopliyses.  3  V.  spurite. 


104 


THE  SKELETON, 


SACRUM. 

The  Sa'crum1  is  a  triangular  bone,  inserted  obliquely  backward  and 
downward  between  the  hip  bones,  at  the  posterior  part  of  the  pelvis. 
Its  base  is  upward,  joining  the  last  lumbar  vertebra ;  its  apex  down- 
ward, joining  the  coccyx. 


FRONT  VIEW  OF  THE  SACRUM.  1,  transverse  ridges, 
indicating  the  original  separation  of  the  bone  into 
five  segments;  2,  sacral  foramina;  3,  promontory; 
4,  articular  surface  for  the  hip  bone;  5,  sacral  bor- 
der of  the  sacro-sciatic  notch ;  6,  base  of  the  sa- 
crum, with  its  articular  surface  for  the  last  lumbar 
vertebra ;  7,  wing  of  the  sacrum ;  8,  articular  proc- 
ess ;  9,  apex  of  the  sacrum,  with  its  articular  sur- 
face for  the  coccyx ;  10,  pedicle  of  the  last  verte- 
bral arch  of  the  sacrum ;  11,  notch  for  the  last  sa- 
cral nerve. 


BACK  VIEW  OF  THE  SACRUM.  1,  rudimental  spi- 
nous  processes ;  2, 2,  sacral  canal,  terminating  below 
in  a  notch  between  the  pedicles,  3,  4,  of  the  last 
vertebral  arch;  3,  3,  rudimental  articular  proc- 
esses; 5,  sacral  foramina;  6,  6,  rudimental  trans- 
verse processes;  7,  articular  surface  for  the  hip 
bone ;  8,  sacral  border  of  the  sacro-sciatic  notches ; 

9,  articular  surface  for  the  last  lumbar  vertebra ; 

10,  articular  processes  for  the  latter  bone ;  11,  apex 
of  the  sacrum ;  12,  rough  surface  on  the  wing  of 
the  sacrum,  for  the  sacro-iliac  ligaments. 


It  is  curved  forward,  and  has  a  broad,  smooth,  concave  surface  in 
front,  and  an  irregular,  narrower,  convex  surface  behind.  It  varies  in 
degree  of  curvature  and  relation  of  length  with  breadth  in  different  indi- 
viduals, as  well  as  sexes.  As  a  general  rule,  it  is  more  curved  and 
longer  in  proportion  with  its  breadth  in  the  male. 

The  bone  corresponds  with  five  vertebrae,  whose  elements  are  more  or 
less  obscured  by  co-ossification  and  feeble  development. 

The  front  surface  of  the  sacrum  exhibits  four  transverse  lines,  indi- 
cating the  original  separation  of  the  bodies  of  the  sacral  vertebrae. 
The  first  division  of  the  bone  presents  an  oval  articular  surface  for  the 


1  Os  sacrum;  os  latum;  os  clunium ;  os  basilare;  os  alagas;  vertebra  magna ; 
lus;  luz ;  clunis;  subvertebra;  hieron  osteon;  albagiazi ;  vetula. 


THE  SKELETON.  105 

body  of  the  last  lumbar  vertebra,  and  the  last  division  a  similar  but 
smaller  surface  for  the  first  piece  of  the  coccyx. 

The  posterior  part  of  the  sacrum  is  composed  of  the  co-ossified  arches 
of  the  vertebral  segments.  The  fifth  arch  is  generally  incomplete  or 
open  at  its  back  part;  and  sometimes  this  condition  extends  to  the  arch 
above,  or  even  through  the  others. 

The  continuation  of  the  spinal  canal  is  called  the  sa'cral  canal',1  and 
is  trilateral.  It  diminishes  in  its  descent,  and  terminates  in  the  notch2 
produced  by  the  incompleteness  of  the  fifth  sacral  arch. 

In  front,  and  behind  the  sacrum,  on  each  side,  are  the  four  sa'cral 
fora'mina,3  which  communicate  with  the  sacral  canal,  and  correspond 
with  the  intervertebral  foramina.  They  successively  diminish  in  size 
from  above  downward,  and  transmit  the  sacral  nerves  and  blood-vessels. 
The  anterior  ones  are  the  larger,  and  lead  outwardly  into  grooves. 

The  spinous  processes  successively  diminish  in  size.  The  upper  three 
are  in  the  .form  of  tubercles,  and  more  or  less  confluent  into  a  ridge.  The 
fourth  one  is  usually  cleft  into  two  tubercles,  which  likewise  conjoin  with 
those  above. 

The  upper  articular  processes  of  the  first  sacral  division  form  vertic- 
ally concave  facets  directed  backward  and  inward.  They  are  separated 
by  a  wide  notch,  which  is  occupied  by  the  last  pair  of  the  yellow  liga- 
ments. The  other  articular  processes  are  rudimental,  and  are  obscurely 
distinguishable  bounding  the  inner  side  of  the  posterior  sacral  foramina. 

The  wings4  or  lateral  portions  of  the  sacrum  correspond  with  the 
ribs  and  transverse  processes  of  the  dorsal  vertebrae,  which  are  here 
fused  together,  so  as  to  afford  a  broad  surface  of  articulation  for  the 
hip  bones.  Below  the  surface  for  the  latter,  the  obtuse  margin  of  the 
bone  gives  attachment  to  the  sacro-ischiatic  ligaments.  The  rough  sur- 
face behind  the  articulation  gives  attachment  to  the  sacro-iliac  ligaments. 


THE   COCCYX. 

The  Coc'cyx3  is  situated  at  the  lower  end  of  the  sacrum,  from  which  it 
curves  downward  and  forward.  It  corresponds  with  four  of  the  true 
vertebras,  and  though  described  as  consisting  of  as  many  pieces,  it  pre- 
sents a  very  variable  condition  of  co-ossification  of  these. 

The  four  bones  successively  decrease  in  size,  and  as  vertebras  become 

1  Canalis  sacralis.  5  Os  coccygis;  caudal  vertebrae  ;  crup- 

2  Hiatus  sacralis.  per  bone ;  rump  bone ;  os  alagas  ;  ossis 

3  F.  sacralia.  sacri  acumen  ;  cauda ;  cuculus ;  uropy- 

4  Aloe  sacraliae.  gion. 


10<5 


THE  SKELETON. 


more  rudiinental. 
FIG.  78. 


POSTERIOR  VIEW  OF  THE  COCCYX. 
1,  first  piece;  2,  2,  pedicles  of  a  ver- 
tebral arch ;  3,  transverse  processes; 
4,  5,  6,  lower  three  pieces  of  the 
coccyx,  consisting  of  rudimental 
vertebral  bodies. 


The  first  of  the  series  has  a  compressed  body,  with  oval 
articular  faces  for  conjunction  with  the  sacrum 
and  the  second  bone  of  the  coccyx.  From 
each  side  projects  a  transverse  process.  This 
is  not  unfrequently  co-ossified  with  the  margin 
of  the  sacrum,  giving  rise  to  a  fifth  sacral  fora- 
men. Behind  the  body  on  each  side  is  another 
short  process,1  which  corresponds  with  the 
pedicle  of  a  vertebral  arch. 

The  remaining  three  bones  present  mere 
flattened  bodies  successively  diminishing  in 
size. 

The  pieces  of  the  coccyx  correspond  with 
the  caudal  or  tail  vertebra?  of  lower  animals. 


DEVELOPMENT  OF  THE  VERTEBRAE. 

Ossification  commences  in  the  vertebra  about  the  seventh  or  eighth 
week  of  embryonic  life,  and  is  not  entirely  completed  until  near  the 
twenty-fifth  year  after  birth. 

As  a  general  rule,  each  true  vertebra  is  developed  from  three  principal 
ossific  points,  of  which  one  belongs  to  the  body,  and  one  to  each  side  of 
the  arch  with  its  processes.  To  these  are  added  five  epiphyses,  of  which 
three  arise  at  the  ends  of  the  spinous  and  transverse  processes,  and  the 
remaining  two  appear  as  thin  plates  on  the  articular  surfaces  of  the 
body. 

FIG.  80. 

FIG.  79. 


DEVELOPMENT  OF  THE  VERTEBR.E.  a,  vertebra 
of  a  foetus,  in  a  cartilaginous  condition,  with  three 
centres  of  ossification;  1,  2,  latent!  pieces;  3,  the 
body ;  6,  vertebra  of  an  infant.  The  lateral  pieces, 
1,  2.  are  co-ossified  at  the  spinous  process,  and  join 
the  body  3,  at  the  sutures  4.  The  ends  of  the  trans- 
verse and  spinous  processes  yet  in  a  cartilaginous 
state. 


DEVELOPMENT  OF  THE  EPIPHYSES  TO  THE  VERTE- 
BRA, a,  dorsal  vertebra,  with  the  epiphyses  4,  5, 
to  the  transverse  processes;  6,  to  the  spinous  pro- 
cess; and  7,  to  the  body;  b, arch  with  its  processes; 
and  c,  body  of  a  lumbar  vertebra;  4,  5,  epiphyses 
of  the  transverse  processes;  6,  of  the  spinous  pro- 
cess; 7,  8,  of  the  body;  9,  10,  of  tubercles  of  the 
upper  articular  processes. 


1  Cornua  sacralia. 


THE  SKELETON.  107 

The  atlas  is  usually  developed  from  three  principal  points  only.  The 
axis  has  two  additional  points  for  the  odontoid  process.  The  anterior 
division  of  the  transverse  process  of  the  last  cervical  vertebra  sometimes 
has  a  distinct  ossific  point,  and  this  is  occasionally  developed  into  a  rudi- 
mental  and  movable  rib. 

The  lumbar  vertebrae  have  epiphyses  at  the  ends  of  the  transverse 
processes  corresponding  with  ribs,  as  well  as  those  upon  the  tubercles 
which  represent  the  true  transverse  processes. 

The  sacrum  has  three  principal  points  of  ossification  for  each  division, 
as  in  the  true  vertebra?.  In  addition  to  these,  epiphysial  plates  form  on 
the  articular  surfaces  of  the  bodies ;  points  originate  on  each  side  of  the 
upper  three  divisions  representing  ribs  ;  and  subsequently  two  epiphysial 
plates  originate  at  each  lateral  border  of  the  bone. 

In  the  coccyx  each  bone  is  developed  from  a  single  ossific  centre. 

ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN. 

The  ligaments  which  connect  the  different  pieces  of  the  vertebral 
column  together  and  with  the  skull  are  as  follows  : — 

Twenty-seven  intervertebral  ligaments. 

Twenty-three  pairs  of  yellow  ligaments. 

The  anterior  vertebral  ligament. 

The  posterior  vertebral  ligament. 

Twenty-five  pairs  of  capsular  ligaments. 

The  supra-spinous  ligament. 

The  interspinous  ligaments. 

The  nuchal  ligament. 

The  anterior  and  posterior  occipito-atloid  ligaments. 

The  anterior  and  posterior  atlo-axoid  ligaments. 

The  transverse  ligament. 

Three  odontoid  ligaments. 

The  Intervert'ebral  liga'ments1  or  disks  are  plates  of  fibro-cartilage 
interposed  between  the  bodies  of  the  vertebrae,  except  the  atlas  and 
axis,  constituting  a  most  tenacious  but  pliant  means  of  connection. 
They  vary  in  thickness  in  different  parts  of  the  vertebral  column  ;  being 
thickest  in  the  lumbar  region,  and  thinnest  in  the  coccyx  and  dorsal 
region.  They  also  vary  in  this  respect  in  different  parts  of  themselves  ; 
thus,  the  disks  of  the  cervical  and  lumbar  regions  are  thickest  in  front, 
while  those  of  the  dorsal  region  are  somewhat  thicker  behind.  To  this 

1  Ligmenta  intervertebralia;  fibro-cartilagines  intervertebrales ;  intervertebral 
substance,  cartilages,  or  fibro-cartilages. 


108 


THE  SKELETON. 


arrangement,  together  with  the  more  or  less  wedge-like  condition  of  the 
vertebral  bodies,  the  curves  of  the  vertical  column  are  due,  excepting 
that  of  the  sacrum,  which  belongs  to  the  bending  of  the  bone  itself. 


FIG.  81. 


FIG.  82. 


UPPER   VIEW   OF    A   LUMBAR   VERTEBRA, 

with  a  horizontal  section  of  an  intervert- 
ebral  ligament.  1,  concentric  layers  of 
fibrous  tissue ;  2,  pulpy  fibro-cartilage. 


VERTICAL  SECTION  OF  TWO  LUMBAR  VERTEBRA,  with  the  in- 
tervening intervertebral  ligament.  The  intervening  articular 
processes,  enveloped  by  a  capsular  ligament,  are  also  repre- 
sented. 1, 1,  concentric  layers  of  fibrous  tissue,  curving  out- 
wardly ;  2,  2,  concentric  layers  curving  inwardly ;  3,  pulpy 
fibro-cartilage  in  the  middle. 


Each  intervertebral  ligament  is  composed  at  the  circumference  of  con- 
centric layers  of  fibrous  tissue,  and  at  the  centre  of  a  pulp-like  fibro-car- 
tilage. The  concentric  layers  consist  of  short  bundles  of  fibres  extended 
obliquely  between  the  vertebraB  and  successively  alternating  in  direction 
in  the  different  laye^,  so  that  if  the  first  proceeds  from  left  to  right,  the 
second  take  their  course  in  the  reverse  direction,  and  so  on  through  the 
series.  The  concentric  layers  are  not  quite  vertical,  but  the  more  super- 
ficial ones  bend  outwardly,  while  the  deeper  ones  bend  inwardly. 

The  interior  pulp-like  fibro-cartilage  appears  to  be  closely  compressed 
in  its  position  ;  so  that  when  an  intervertebral  disk  is  cut  through,  the 
fibro-cartilage  rises  above  the  level  of  the  exposed  surface. 

The  intervertebral  ligaments,  while  firmly  associating  the  segments 
of  the  vertebral  column,  at  the  same  time  give  it  a  decided  though 
restricted  flexibility.  The  exterior  concentric  fibrous  layers  strongly 
attach  the  vertebral  bodies,  while  their  alternately  crossing  arrange- 
ment permits  a  slight  degree  of  torsion  or  twisting  motion  ;  and  at  the 
same  time  the  interior  compressed  fibro-cartilage  gives  elasticity  to  the 
structure. 

Under  pressure  of  the  body  in  its  erect  position,  the  curvature  of  the 
concentric  layers  of  the  intervertebral  ligaments  increases,  and  the  fibrous 
bundles  composing  them  become  more  depressed,  so  that  the  trunk 
diminishes  in  length.  In  the  recumbent  position,  pressure  being  removed, 


THE  SKELETON. 


109 


FIG.  83. 


the  condition  is  reversed  ;  and  in  this  manner  may  be  explained  the  fact 
that  a  man  is  slightly  taller  on  rising  from  bed  in  the  morning  than  on 
retiring  at  night. 

In  the  conjunction  of  the  vertebral  bodies  by  means  of  the  interverte- 
bral  ligaments,  we  may  discover  some  analogy  to  the  ball-and-socket 
joint,  which  allows  movement  in  all  directions,  though  in  this  case  it  is 
of  a  very  restricted  character.  The  interior  compressed  fibro-cartilage  of 
the  disks  between  the  resisting  vertebral  bodies  serves  the  part  of  a  ball, 
while  the  exterior  concentric  layers  of  alternately  crossing  fibrous  bun- 
dles act  as  check  ligaments.  The  entire  arrangement  is  an  admirable 
provision,  to  give  a  slight  degree  of  movement  in  all  directions  to  the 
vertebral  column  without  endangering  the  integrity  of  the  delicate  nerv- 
ous cord  which  it  incloses  and  protects. 

The  Yellow  lig'aments,1  of  which  there  are  twenty-four  pairs,  situ- 
ated between  the  vertebral  arches  from  the  axis  to  the  sacrum,  are  most 
distinctly  seen  within  the  spinal  ca- 
nal. They  are  attached  to  the  an- 
terior surface  of  the  lower  part  of 
the  arches  above,  and  the  posterior 
surface  of  the  upper  part  of  those 
below,  between  the  position  of  the 
spinous  and  transverse  processes. 
They  are  composed  of  yellow,  elas- 
tic tissue,  the  fibres  of  which  are 
extended  between  the  vertebral 
arches. 

The  Anterior  vert'ebral  lig'a- 
ment2  is  a  strong  band  extending 
the  entire  length  of  the  vertebral 
column,  from  the  basilar  process  of 
the  occipital  bone  to  the  end  of  the  coccyx.  Its  upper  extremity  forms  a 
rounded  end,  and  is  usually  viewed  as  a  distinct  ligament.3  It  widens  in 
its  descent,  is  thickest  and  most  obvious  opposite  the  vertebral  bodies, 
thinnest  upon  the  sacrum,  and  adheres  most  tightly  to  the  intervertebral 
disks  and  the  contiguous  margins  of  the  vertebral  bodies.  It  is  com- 
posed of  closely  associated  bundles  of  fibres,  of  which  the  superficial 


THREE  VERTEBRAL  ARCHES  REMOVED  FROM  AS  MANY 
DORSAL  VERTEBR.E,  viewed  in  front,  and  exhibiting 
1,  the  yellow  ligaments ;  and  2,  the  capsular  liga- 
ments of  the  articular  processes. 


1  L.  flava;  1.  subflava ;  1.  intercruralia. 

2  Anterior    common    ligament ;    liga- 
mentum  longitudinale   anterius;  1.  cor- 
poribus  vertebrarum  commune  anterius; 


fascia  longitudinalis  anterior.    Its  lower 
end,  the  1.  sacro-coccygeum  anterins. 

3  Anterior  middle  occipito-atloid  liga- 
ment. 


110 


THE   SKELETON. 


extend  the  length  of  three  or  four  vertebrae ;   those  deeper,  the  length 
of  two  or  three ;  and  the  deepest,  between  the  contiguous  vertebra. 


FIG.  84. 


PORTION  OF  THE  OCCIPITAL  BONE,  WITH  THE  ATLAS 
AND  AXIS,  front  view.  1,  origin  of  the  anterior  ver- 
tebral ligament  from  the  basilar  process;  2,  ante- 
rior occipito-atloid  ligament  on  each  side  of  the 
former ;  3,  widening  of  the  anterior  vertebral  lig- 
ament from  the  axis ;  4,  anterior  atlo-axoid  liga- 
ment; 5,  6,  7,  capsular  ligaments  of  the  articular 


THREE  DORSAL  VERTEBRA,  with  the  articulations 
of  the  ribs,  viewed  in  front.  1,  portion  of  the  an- 
terior vertebral  ligament ;  2,  radiating  ligament ;  3, 
anterior  costo-transverse  ligament;  4,  articulation 
of  the  head  of  the  rib,  laid  open,  and  exhibiting 
the  interarticular  ligament  separating  two  synovial 
cavities. 


This  ligament,  besides  forming  a  strong  bond  of  union  to  the  verte- 
brae, also  affords  an  origin  to  the  crura  of  the  diaphragm,  and  gives 
attachment  to  the  pharynx  and  oesophagus,  the  aorta,  thoracic  duct, 
azygos  vein,  and  inferior  cava. 

The  Posterior  vert'ebral  lig'ament1  is  a  strong  fibrous  band,  with  fes- 


FIG.  86. 


FIG.  87. 


PORTION  OF  THE  CRANIUM  AND  OF  THE  ATLAS  AND 
AXIS,  viewed  from  behind ;  the  posterior  portions 
of  the  occipital  and  two  last  bones  removed.  1, 
declivity  of  the  sphenoid  bone;  2,  occipital  bone; 
3,  atlas ;  4,  axis ;  5.  origin  of  the  posterior  verte- 
bral ligament  from  the  basilar  process ;  6, 7,  capsu- 
lar ligaments  of  the  articular  processes. 


BODIES  OF  THREE  DORSAL  VERTEBRA,  connected  by 
the  intervertebral  ligaments,  viewed  from  behind; 
the  vertebral  arches  having  been  removed.  1, 
intervertebral  ligaments ;  2,  pedicles  of  the  verte- 
bral arches;  3,  portion  of  the  posterior  vertebral  lig- 
ament, exhibiting  its  lateral  festooned  borders,  4. 


THE  SKELETON.  Ill 

tooned  margins,  situated  within  the  spinal  canal,  and  extending  from  the 
inner  surface  of  the  basilar  process  of  the  occipital  bone  to  the  end  of 
the  coccyx.  In  its  course  it  widens  opposite  the  intervertebral  disks,  to 
which  and  the  contiguous  margins  of  the  vertebral  bodies  it  tightly 
adheres  ;  and  it  narrows  toward  the  middle  of  the  latter,  from  which  it 
is  separated  by  the  transverse  veins  of  the  spinal  sinuses. 

The  articular  processes  of  the  vertebrae  are  invested  with  cartilage ; 
and  each  joint  possesses  a  synovial  membrane  and  a  thin  capsular  liga- 
ment.2 The  extent  of  motion  in  the  joints  formed  by  the  vertebral  artic- 
ular processes  generally  is  very  feeble,  consisting  only  of  a  slight  gliding 
in  the  bending  of  the  vertebral  column. 

The  Su/pra-spi'nous  lig'ament3  is  a  thin  fibrous  band  connecting  the 
summits  of  the  spinous  processes  from  the  last  cervical  vertebra  to  the 
end  of  the  coccyx.  It  is  strongest  in  the  lumbar  region,  and  is  continu- 
ous at  its  upper  extremity  with  the  nuchal  ligament.  Its  lower  extremity, 
by  expanding,  closes,  in  this  position,  the  spinal  canal. 

The  Interspi/nous  lig'aments4  are  thin  fibrous  membranes  connecting 
the  contiguous  spinous  processes  of  the  vertebra,  and  extending  from  the 
former  ligament. 

The  Nu/clial  lig'ament5  is  a  partition  of  loose  fibrous  tissue,  separat- 
ing the  muscles  of  the  two  sides  of  the  neck,  and  extending  from  the 
cervical  spinous  processes  along  the  median  line  of  the  occipital  bone  to 
the  occipital  protuberance.  In  man  this  ligament  is  a  mere  rudiment  of 
the  powerful  elastic  nuchal  ligament  which  sustains  the  pendant  head  in 
quadrupeds. 

ARTICULATIONS  OF  THE  OCCIPITAL  BONE,  THE  ATLAS,  AND 

THE  AXIS. 

The  Anterior  and  posterior  occip'ito-at'loid  lig'aments6  are  thin,  broad 
fibrous  membranes  extended  between  the  contiguous  borders  of  the 
occipital  foramen  and  atlas,  before  and  behind  the  position  of  the  con- 
dyles  and  articular  processes. 

1  Posterior  common  ligament ;  1.  longi-  4  Lig.  interspiualia ;  membrana  inter- 
tudinale  posterius;   1    corporibus  verte-       spinalis 

brarum  posterius;  fascia  longitudinalis  5Lig.  nuchre;  fascia  nuchalis ;  paxy- 
postica.     The  upper  extremity,  usually  waxy  ;  paxwax  ;  packwax ;  faxwax ;  tax- 
described  as  distinct,  with   the   names  wax  ;  lig.  cervical ;  descending  ligament 
apparatus  ligamentosus,  membrana  liga-  of  Diemerbroeck. 
inentosa,  and  occipito-axoidean  ligament.  6  Membrana  annuli  anterioris  et  pos- 

2  Ligamenta  processuum  obliquorum.  terioris  atlantis;    m.  obturatoria    ante- 

3  Ligamentum  apicum ;  its  lower  end,  rior  et  posterior, 
the  lig.  sacro-coccygeum  posticum. 


112 


THE  SKELETON. 


The  Anterior  and  posterior  at'lo-ax'oid  lig'aments  are  likewise  thin 
fibrous  membranes,  the  former  connecting  the  anterior  bridge  of  the  atlas 
with  the  front  of  the  body  of  the  axis,  and  the  latter  connecting  the 
contiguous  borders  of  the  arches  of  the  atlas  and  axis. 


FIG. 


FIG.  80. 


PORTION  OF  THE  OCCIPITAL  BONE,  WITH  THE  ATLAS 
AND  AXIS,  front  view.  1,  origin  of  the  anterior 
vertebral  ligament ;  2,  anterior  occipito-atloid  liga- 
ment on  each  side  of  the  former ;  3,  widening  por- 
tion of  the  anterior  vertebral  ligament ;  4,  anterior 
atlo-axoid  ligament ;  5,  6,  7,  capsular  ligaments  of 
the  articular  processes. 


PORTION  OF  THE  OCCIPITAL  BONE  AND  THE  UPPER 
THREE  CERVICAL  VERTEBRAE.  1,  atlas ;  2,  axis ;  3, 
posterior  occipito-atloid  ligament;  4,  capsular  lig- 
aments of  the  occipital  condyles  and  articular 
processes  of  the  atlas;  5,  posterior  atlo-axoid  liga- 
ment ;  6,  capsular  ligaments  of  the  articular  proc- 
esses between  the  atlas  and  axis ;  7,  first  pair  of 
yellow  ligaments;  8,  capsular  ligaments  of  the  ar- 
ticular processes  between  the  second  and  third  cer- 
vical vertebrae. 

The  membranes  constituting  the  above  four  ligaments  are  compara- 
tively loose  and  flexible,  so  as  not  to  interfere  with  the  peculiar  move- 
ments of  the  skull  and  first  pair  of  cervical  vertebra?. 

The  capsular  ligaments  of  the  articular  processes  of  the  occiput,  atlas, 
and  axis  are  likewise  comparatively  loose,  so  as  to  permit  rotation, 
flexion,  and  extension  of  the  head. 

The  Trans 'verse  lig'ament1  is  a 
strong  band  extended  between  the 
tubercles  on  the  inner  side  of  the 
atlas,  and  serves  the  purpose  of  re- 
taining the  odontoid  process  of  the 
axis  in  its  proper  position.  To 
render  its  functions  more  effective, 
it  sends  from  its  middle  a  process 
upward,  to  be  attached  to  the  ante- 
rior border  of  the  occipital  fora- 
men, a»d  another  one  downward, 
to  be  attached  at  the  root  of  the 
odontoid  process,  so  that  altogether 
it  has  a  crucial  form.2 


FIG.  90. 


PORTION  OF  THE  SKULL,  THE  ATLAS,  AND  AXIS, 
viewed  from  behind ;  the  posterior  portions  of  the 
occipital  and  two  latter  bones  removed.  1,  up- 
per extremity  of  the  posterior  vertebral  ligament; 
2,  transverse  ligament,  with  its  two  appendices,  3 
and  4;  5,  odontoid  ligaments;  6,7,  capsular  liga- 
ments. 


1  L.  transversum  atlantis;  1.  transversale. 


2  L.  cruciatum. 


THE   SKELETON.  H3 

The  Odon'toid  lig'aments1  are  three  bands  which  ascend  from  the 
sides  and  summit  of  the  odontoid  process  of  the  axis,  to  be  attached  to 
the  anterior  border  of  the  occipital  foramen.  The  lateral  bands  are 
much  stronger  than  the  middle  one.  These  ligaments  serve  to  limit  the 
rotary  movement  of  the  head. 

The  contiguous  surfaces  of  the  odontoid  process  and  atlas  are  invested 
with  cartilage,  and  form  a  joint  lined  with  a  synovial  membrane  and  en- 
circled with  a  capsular  ligament.2  A  similar  joint  is  formed  between  the 
odontoid  process  and  the  transverse  ligament. 

The  movements  of  flexion  and  extension  of  the  head,  as  before  indi- 
cated, occur  between  the  occipital  bone  and  atlas,  for  which  the  pecu- 
liar construction  of  the  condyles  of  the  former  and  articular  processes 
of  the  latter  are  well  adapted ;  while  they  are  limited  in  extent  by  the 
capsular,  occipito-atloid,  and  nuchal  ligaments.  The  rotary  movement 
of  the  head  occurs  between  the  atlas  and  axis ;  the  centre  of  motion 
being  the  odontoid  process,  and  the  circle  of  rotation  the  contiguous 
articular  processes.  It  is  limited  by  the  capsular,  atlo-axoid,  and  odon- 
toid ligaments.  The  general  flexibility  of  the  cervical  portion  of  the 
vertebral  column  permits  a  slight  increase  in  the  movements  indicated. 

THE  VERTEBRAL  COLUMN  VIEWED  ENTIRE. 

The  Vertebral  column  averages  about  two  and  a  quarter  feet  in  length, 
and  varies  but  little  in  this  respect  in  comparison  with  the  stature  of 
persons,  the  difference  depending  more  on  the  proportionate  length  of  the 
lower  extremities. 

The  first  vertebra  forms  a  capital  to  the  column  sustaining  the  head. 
The  other  true  vertebrae  successively  increase  in  bulk,  forming  a  tapering 
column  resting  with  its  base  upon  the  sacrum,  which,  like  the  key-stone 
of  an  arch,  is  inserted  between  the  hip  bones. 

The  breadth  of  the  vertebrae  increases  from  the  second  to  the  seventh, 
then  decreases  to  the  fourth  of  the  dorsal  region,  and  afterwards  grad- 
ually increases  again  to  the  sacrum,  which  rapidly  diminishes  to  the  end 
of  the  coccyx.  The  height  of  the  cervical  vertebra?  is  nearly  uniform ; 
the  others  gradually  increase  in  this  respect  to  the  last. 

The  intervertebral  ligaments  gradually  increase  in  thickness  from  the 
third  dorsal  vertebra  to  the  sacrum.  Above  the  former  point  they 
increase  to  the  middle  of  the  neck,  and  then  again  decrease. 

1  Ligamenta  alaria  and  1.  rectum  medium ;  1.  dentis  suspensorium ;  moderator  and 
middle  straight  ligaments.  2  Vaginal  ligament. 

8 


114  THE   SKELETON. 

The  intervals  between  the  vertebral  arches  are  occupied  by  the  yellow 
ligaments.  They  are  widest  in  the  loins,  and  least  so  in  the  lower  por- 
tion of  the  neck  and  back. 

The  spi'nal  canal71  is  largest  and  is  triangular  in  the  neck  and  loins, 
is  narrower  and  cylindrical  in  the  dorsal  region,  and  is  smallest  and 
triangular  in  the  sacrum. 

The  intervertebral  foramina  increase  in  size  from  the  first  to  the  last ; 
the  sacral  foramina  successively  decrease. 

The  spaces  between  the  spinous  and  transverse  processes  constitute 
the  vertebral  gutters,  and  are  occupied  by  the  extensor  muscles  of  the 
back. 

Viewed  in  profile,  the  vertebral  column  presents  a  series  of  four  curves, 
which,  except  in  the  case  of  the  sacrum,  depend  on  the  difference  in 
thickness  between  the  fore  and  back  parts  of  the  vertebral  bodies  and 
the  intervertebral  disks.  In  the  neck  and  loins  the  convexity  of  the 
curves  is  directed  forward,  in  the  dorsal  region  and  pelvis  backward. 
The  strongest  degree  of  convexity  is  that  presented  in  the  loins ;  its 
lower  part  being  produced  by  the  promontory  of  the  sacrum. 

The  curvatures  commence  to  become  particularly  evident  with  the  first 
efforts  of  the  child  to  stand  or  walk ;  prior  to  this  period  the  vertebral 
column  being  nearly  straight. 

More  or  less  lateral  curvature  is  quite  frequently  observable  in  the 
dorsal  region,  most  usually  with  the  convexity  toward  the  right.  This 
abnormal  character  appears  to  depend  on  the  excess  of  muscular  action 
upon  the  side  to  which  the  convexity  is  directed. 

The  sacrum  is  the  only  portion  of  the  vertebral  column  which  is 
entirely  immovable,  and  it  is  through  this  bone  that  the  weight  of  the 
trunk  is  communicated  to  the  lower  extremities.  The  mobility  in  other 
portions  of  the  vertebral  column  varies,  being  greatest  in  the  cervical 
region,  and  least  in  the  dorsal  region. 

The  motions  of  the  vertebral  column,  though  very  restricted,  occur  in 
all  directions ;  being  those  of  flexion  and  extension,  bending  to  either 
side,  and  rotation  upon  its  axis. 

THE  EIBS. 

The  Eibs,2  of  which  there  are  twelve  pairs,  form  a  series  of  narrow 
arches  on  each  side  of  the  trunk,  extending  from  the  dorsal  vertebrae 
toward  the  sternum.  Anteriorly  they  are  prolonged  by  the  cos'tal  car'- 

1  Vertebral  canal ;    rachidian   canal ;  2  Costae ;     pleurae  ;     pleurapophyses  ; 

canalis   medullaa   spinalis ;    specus  pro      pleuromata. 
medulla  spinali,  or  vertebralis ;  solen. 


THE   SKELETON. 


115 


tilages.1  The  upper  seven  pairs  join  the  side  of  the  sternum  through  the 
latter,  and  are  called  true  or  ster'nal  ribs.2  Of  the  others,  called  false 
or  aster'nal  ribs,3  three  successively  join  one  another  and  the  cartilage 
of  the  last  true  rib,  by  means  of  their  cartilages.  The  remaining  two 
have  their  cartilages  unattached,  and  are  thence  called  free  or  floating 
ribs.4 

The  ribs  successively  increase  in  length  from  the  first  to  the  eighth, 
and  then  decrease  to  the  last  one. 
In  breadth  and  degree  of  curva- 
ture they  gradually  diminish  from 
first  to  last.  In  direction  from  the 
vertebral  column,  they  are  first  di- 
rected from  the  bodies  outward 
and  backward  to  the  transverse 
processes,  from  thence  outward  and 
slightly  forward,  and  subsequently 
more  abruptly  forward  and  inward. 
In  proceeding  from  the  vertebrsB 
they  likewise  incline  downward,  so 
that  their  anterior  extremity  is 
lower  than  the  posterior.  In  the 
latter  direction  the  ribs  exhibit  a 
slight  twist,  so  that  they  will  not 
lie  with  their  whole  length  in  con- 
tact with  a  level  surface. 

The  ribs  have  an  outer  and  inner 
broad  smooth  surface  ;  an  upper 
rounded  border  and  a  lower  sharp 
one.  Within  the  greater  part  of 
the  length  of  the  lower  border 
there  is  a  groove5  for  the  intercostal  blood-vessels. 

The  posterior  extremity  of  a  rib  is  the  head,6  and  this  presents  two 
articular  facets,  separated  by  a  slight  ridge,  which  articulate  with  the 
corresponding  facets  of  a  contiguous  pair  of  vertebral  bodies.  The 
narrow  part  of  the  rib  succeeding  the  head  is  its  neck,7  and  this  is  bounded 
externally  by  the  tu/bercle,8  upon  which  is  an  articular  facet  for  the 
transverse  process  of  the  lower  of  the  two  vertebra?  joined  by  the 


FRONT  VIEW  OF  THE  THORAX.  1,  2,  3,  the  three 
pieces  of  the  sternum;  4,  5,  the  dorsal  vertebrse; 
6,  the  first  true  rib;  7,  its  head;  8,  neck ;  9,  tubercle; 
10,  the  seventh  true  rib ;  11,  costal  cartilages  ;  12, 
the  floating  ribs;  13,  groove  for  the  intercostal 
blood-vessels. 


1  Cartilagines  costarum  ;  haemapophy- 
ses. 

2  Costae  verge ;  c.  genuinae ;  c.  sternales. 

3  Costae  spuriae ;  c.  mendosae ;  c.  aster- 
nales  ;  nothae  costae. 


4  Costae  fluctuantes. 

5  Sulcus  costalis. 

6  Capitulum  costaa. 

7  Cervix ;  collum. 

8  Tuberculum. 


116  THE   SKELETON. 

head  of  the  rib.  Externally  to  the  tubercle  is  a  rough  mark  called  the 
angle,1  corresponding  with  the  point  at  which  the  rib  is  rather  abruptly 
directed  forward.  The  distance  of  the  angle  from  the  tubercle  succes- 
sively increases  from  the  first  to  the  last  rib. 

The  anterior  extremity  of  the  rib  is  the  most  compressed  portion,  is 
obtuse  at  both  borders,  and  is  continuous  with  its  costal  cartilage,  which, 
after  separation  by  maceration,  leaves  an  elliptical  pit  at  the  end  of  the 
bone. 

The  broad  surfaces  of  the  ribs  are  so  arranged  in  succession  that  the 
outer  ones  present  the  periphery  of  an  oval,  and  the  inner  ones  in  the 
same  manner  are  related  to  the  interior  of  an  oval. 

Several  of  the  ribs  present  exceptional  characters  to  those  given  in 
the  general  account.  The  first  rib  has  no  twist,  has  its  broad  surfaces 
directed  upward  and  downward,  and  its  borders,  which  are  narrow,  inward 
and  outward.  The  upper  surface  at  its  fore  part  is  marked  by  two  slight 
impressions  produced  by  the  subclavian  blood-vessels.  The  head  presents 
but  a  single  articular  facet.  The  eleventh  and  twelfth  ribs  are  compara- 
tively feebly  developed;  have  only  one  articular  facet  to  the  head,  and 
have  no  tubercle. 

The  Cos'tal  cartilages2  successively  increase  in  length  from  the  first 
to  the  seventh,  and  then  decrease  to  the  last.  Their  direction  is  one  of 
convergence  toward  the  sternum ;  the  first  one  descends,  that  succeeding 
is  horizontal,  and  the  others  gradually  become  more  and  more  ascending. 

The  outer  extremity  of  the  costal  cartilages  is  absolutely  continuous 
with  the  structure  of  the  ribs.  The  inner  extremity  of  those  of  the  true 
ribs,  except  the  first  pair,  forms  a  movable  articulation  with  the  side  of 
the  sternum.  The  inner  end  of  the  succeeding  three  pairs  of  cartilages 
is  pointed  and  attached  to  the  cartilage  next  above.  The  last  two  pairs 
of  costal  cartilages  are  pointed  and  free. 

Between  the  fifth  to  the  eighth  pair  of  costal  cartilages,  processes 
usually  exist  blending  their  contiguous  borders  together. 

The  ribs  commence  ossification  even  before  the  vertebra?.  They  are 
formed  from  a  principal  piece,  an  epiphysis  for  the  head,  and  another  for 
the  tubercle,  except  in  the  last  two  pairs,  which  have  no  epiphysis  for 
the  latter  process. 

Usually  after  the  prime  of  life,  in  the  male,  the  costal  cartilages 
become  partially  ossified,  but  in  the  female  this  is  much  less  liable  to 
occur,  and  then  only  in  advanced  age. 

1  Angulus,  or  cubitus  costse.  2  Cartilagines  costarum ;  hgemapophyses. 


THE   SKELETON.  H7 


THE  STERNUM. 

The  Ster'num  or  breast  bone1  is  situated  in  the  median  line,  in  front  of 
the  thorax,  sloping  from  above  downward  and  forward.  It  is  long, 
broad,  and  nearly  flat,  and  bears  a  general  resemblance  to  the  ancient 
broad-sword,  from  which  the  older  anatomists  called  its  three  pieces  the 
handle,  the  blade,  and  the  point.  Its  anterior  surface  is  slightly  convex ; 
its  posterior  surface  slightly  concave.  In  structure  it  is  light  and  spongy, 
and  is  invested  with  a  thin  layer  of  moderately  compact  substance. 

The  handle  or  first  piece2  is  the  broadest  and  thickest  bone  of  the 
sternum.  It  is  irregularly  hexahedral ;  slightly  convex  in  front,  and 
slightly  concave  behind.  Its  upper  border  is  thick,  rounded,  and  trans- 
versely concave  ;3  its  lower  border  is  straight,  and  joins  the  second  bone 
of  the  sternum.  The  upper,  short,  lateral  border  slopes  off  and  articu- 
lates with  the  clavicle.*  The  lower,  long,  lateral  border  curves  downward 
and  inward ;  its  upper  end  is  continuous  with  the  first  costal  cartilage ; 
its  lower  end  articulates  with  part  of  the  second  costal  cartilage. 

The  second  piece  or  body5  is  the  longest  portion  of  the  sternum.  It 
is  oblong,  quadrate  in  form,  and  usually  widest  at  its  lower  part.  Its 
anterior  and  posterior  surfaces  are  nearly  flat,  and  are  commonly  more 
or  less  marked  by  several  transverse  lines  indicating  the  original  separa- 
tion of  the  bone  into  parts.  Its  lateral  borders  present  successively,  first, 
at  the  upper  end  an  articular  surface  forming  part  of  the  articulation 
for  the  second  costal  cartilage,  then  four  notches  for  the  third  to  the  sixth 
costal  cartilages  inclusive,  and  finally,  at  the  lower  end  a  surface  for  part 
of  the  seventh  costal  cartilage.  The  distance  between  these  articulations 
successively  decreases  from  above  downward. 

The  third  piece  or  point6  of  the  sternum  is  usually  the  narrowest, 
thinnest,  and  shortest  portion.  It  is  quite  variable  in  shape,  being  flat, 
long  and  pointed,  or  ensiform;  tongue-shaped,  or  discoidal;  or  it  is 
forked.  It  commences  ossification  several  years  after  birth,  and  even  in 
advanced  age  is  rarely  entirely  ossified ;  hence  its  name  of  en'siform 
car'tilage.7  With  the  commencement  of  its  lateral  border,  the  seventh 
costal  cartilage  partially  articulates. 

The  upper  two  pieces  of  the  sternum  commence  ossification  about  the 
fifth  or  sixth  month  of  foetal  life ;  and  they  do  so  from  a  variable  number 

1  Sternon ;  os  pectoris  ;  o.  xiphoides ;  *  Incisura  clavicularis. 

o.  gladioli;   o.  ensiforme;  o.  asser;scu-          5  Corpus;  blade;  mesosternum. 
turn  pectoris,  or  cordis ;  haemal  spine.  6  Processus  xiphoideus;  p.  mucrona- 

2Manubrium;  episternum.  tus  ;  p.  ensiformis  ;  hyposternum. 

3  Incisura  semilunaris ;  os  jugularis.  7  Cartilage  ensiformis. 


118 


THE   SKELETON. 


of  points.  At  puberty  the  handle  forms  a  single  bone  ;  the  body  usually 
presents  five  segments,  which  successively  co-ossify  from  below  upward. 
Generally  the  three  pieces  or  bones  of  the  sternum  remain  separated,  but 
frequently  the  upper  two  become  united,  and  occasionally  in  old  age  all 
three  are  found  co-ossified. 

The  sternum  is  variable  in  its  form  in  different  individuals,  principally 
in  the  proportion  of  length  and  breadth  of  the  different  pieces. 

Articulations  of  the  Sternum. — The  three  pieces  of  the  sternum  are 
conjoined  by  fibro -cartilage,  and  are  much  strengthened  in  their  union 
by  a  thick  fibrous  investment,  partially  derived  from  the  costo-sternal 
ligaments. 

ARTICULATIONS  OF  THE  RIBS  WITH  THE  VERTEBRAE  AND 

STERNUM. 

Costo-vertebral  articulations. — The  articulation  between  the  head  of 
the  ribs  and  the  bodies  of  the  dorsal  vertebra  is  surrounded  with  a  cap'- 
sular  lig'ament,  and,  except  in  the  case  of  that  of  the  first  and  the  last 
two  ribs,  is  divided  into  two  parts  by  an  inter  artic'ular  lig'ament,1 

FIG.  93. 


FIG.  92. 


ANTERIOR  VIEW  OF  THREE  DORSAL  VERTEBRA  AND 

THEIR    ARTICULATION  WITH   THE    RIBS.      1,  portion  of 

the  anterior  vertebral  ligament ;  2,  radiating  liga- 
ment ;  3,  anterior  costo-transverse  ligament ;  4,  ar- 
ticulation of  the  head  of  the  rib  laid  open,  exhibit- 
ing the  cavity  divided  into  two  by  aninterarticular 
ligament. 


POSTERIOR  VIEW  OF  FOUR  DORSAL  VERTEBRAE  AND 

THEIR   ARTICULATION    WITH    THE    RIBS.      1,  SUpni-Spi- 

nous  ligament;  2,  yellow  ligament,  seen  just  below 
the  edge  of  the  vertebral  arches ;  3,  anterior  costo- 
transverse  ligaments ;  4,  posterior  costo-transverse 
ligaments. 


which  is  a  short  band  connecting  the  ridge  on  the  head  of  the  ribs  with 
the  contiguous  intervertebral  disk.  In  front  the  articulation  is  strength- 
ened by  the  ra'diating  lig'ament,2  consisting  of  three  bands  diverging 


1  L.  interarticulare ;  1.  transversum. 


2  L.  capituli  costoe  anterius ;  1.  radiatum. 


THE   SKELETON.  H9 

from  the  head  of  the  rib  to  the  sides  of  the  contiguous  pair  of  vertebral 
bodies  and  the  intervertebral  disk. 

The  slightly  movable  articulation  between  the  tubercle  of  the  upper 
ten  ribs  and  the  neighboring  transverse  processes  of  the  dorsal  vertebrae 
is  likewise  surrounded  with  a  cap'sular  lig'ament  Besides  this,  each  rib 
is  connected  with  the  transverse  processes  by  three  ligaments,  as  follows  : 

The  anterior  cos'to-trans'verse  lig'ament,1 — This  is  a  membranous 
band  connecting  the  neck  of  the  rib  with  the  transverse  process  above. 

The  posterior  cos'to-trans'verse  lig'ament.2 — This  is  a  short  band 
connecting  the  tubercle  of  the  ribs  with  the  end  of  the  contiguous  trans- 
verse process. 

The  middle  cos'to-trans'verse  lig'ament,3 — This  consists  of  short 
fibres  intervening  between  the  neck  of  the  rib  and  the  contiguous  trans- 
verse process. 

Costo-sternal  articulations. — The  costal  cartilages,  except  the  first, 
form  articulations  with  the  side  of  the  sternum  surrounded  by  capsular 
ligaments  and  lined  with  synovial  membranes.  Behind,  and  especially  in 
front,  the  articulations  are  strengthened  by  fibres  radiating  from  the  cos- 
tal cartilages  upon  the  sternum,  constituting  the  anterior  and  posterior 
cos'to-ster'nal  lig'aments.4  Those  of  the  two  sides  blend  together  and 
with  the  aponeurotic  origin  of  the  pectoral  muscles. 

A  thin  fibrous  band  connecting  the  seventh  costal  cartilage  with  the 
third  piece  of  the  sternum  is  called  the  cos'to-xi'phoid  lig'ament.5 

The  contiguous  margins  of  the  costal  cartilages  from  the  sixth  to  the 
ninth,  if  not  blended  together,  have  opposed  articular  surfaces  surrounded 
with  cap'sular  lig'aments. 

THE  THORAX. 

The  Tho'rax  or  chest6  is  a  conical  or  ovoidal  case,  with  its  narrower 
part  uppermost.  It  is  flattened  before  and  behind,  which  is  the  reverse 
of  the  condition  observable  in  the  lower  mammals  generally,  and  hence 
it  is  that  man  can  readily  lie  on  his  back,  while  the  lower  animals  cannot. 

It  is  formed  of  the  dorsal  vertebrae,  ribs,  and  sternum ;  and  its  sides 
are  also  called  its  walls. 

1  L.   costo-transversale    anterius;     1.  3  L.  costo-trans.  medius;  1  colli  costse; 
transversarium    internum;     int.    costo-      1.  cervicum  costse. 

transverse  ligament ;    1.  costo-transver-  *  L.  costo-sternalia  ant.   et  post. ;    1. 

sarium  inferius.  radiata. 

2  L.  costo-transversale   posterius  ;    1.  &  L.  costo-xiphoideum. 
transversarium   externum;     ext.   costo-  6  Pectus ;  stethus;  cassa;  venter  me- 
transverse  ligament.  dius;   citharus;    scutum   pectoris ;   bir; 

chelys. 


120 


THE  SKELETON. 


The  front  wall  of  the  chest,  or  the  breast,  is  flatter  and  shorter  than 
any  other  portion,  and  is  formed  of  the  sternum  and  cartilages  of  the 
true  ribs.  It  slopes  forward  and  downward  to  such  an  extent  that  the 

lower  end  of  the  sternum  is  re- 
moved twice  the  distance  of  the 
upper  end  from  the  vertebrae. 

The  posterior  wall  is  the  back, 
in  the  most  restricted  use  of  the 
term.  It  is  also  flattened,  is  di- 
vided in  the  middle  by  the  imbri- 
cating spinous  processes  of  the  dor- 
sal vertebrae,  and  is  denned  on  each 
side  by  the  angles  of  the  ribs, 
which  indicate  the  extent  to  which 
the  dorsal  extensor  muscles  reach 
outwardly. 

The  lateral  walls  of  the  chest 
are  the  longest,  most  prominent, 
and  convex. 

The  cavity  of  the  tho'rax1  is 
subdivided  posteriorly  by  the  intru- 
sion of  the  bodies  of  the  dorsal 
vertebrae ;  and  it  is  open  above, 
below,  and  between  the  ribs. 

The  superior  opening  of  the 
tho'rax2  is  formed  by  the  first  dor- 
sal vertebra,  the  first  pair  of  ribs,  and  the  first  piece  of  the  sternum.  It 
is  reniform,  with  its  transverse  diameter  more  than  twice  as  great  as  the 
antero-posterior,  and  with  its  plane  inclining  a  little  downward  and 
forward. 

The  inferior  opening,3  by  far  the  largest,  is  formed  by  the  last  dorsal 
vertebra,  the  last  pair  of  ribs,  the  cartilages  of  all  the  false  ribs,  and  the 
last  piece  of  the  sternum.  It  is  likewise  reniform,  with  its  transverse 
diameter  about  one-third  greater  than  the  antero-posterior,  and  with  its 
plane  inclining  upward  and  forward. 

The  intercostal  spaces4  increase  in  width  anteriorly,  and  are  occupied 
by  muscles  of  the  same  name. 

The  greatest  circumference  of  the  thorax  is  just  below  the  middle,  and 
not  at  the  bottom  or  base.  The  ribs  incline  downward  and  forward  in 
such  a  manner  that  the  anterior  extremity  of  the  first  rib  is  on  a  level 


FRONT  VIEW  OF  THE  THORAX.  1,  2.  3,  the  three 
pieces  of  the  sternum ;  4,  5,  the  dorsal  vertebrae ; 
6,  the  first  true  rib;  7,  its  head;  8,  neck;  9,  tu- 
bercle ;  10,  the  seventh  true  rib ;  11,  costal  cartil- 
ages; 12,  the  floating  ribs;  13, groove  for  the  inter- 
costal blood-vessels. 


1  Cavum  thoracis. 

2  Apertura  thoracis  superior. 


3  Apertura  thoracis  inferior. 

4  Spatia  intercostalia. 


THE   SKELETON.  121 

with  the  second  dorsal  vertebra,  the  anterior  extremity  of  the  seventh 
rib  is  on  a  level  with  the  tenth  dorsal  vertebra,  and  the  end  of  the  last 
rib  is  on  a  level  with  the  first  lumbar  vertebra. 

The  movements  of  the  thorax  consist  of  a  moderate  degree  of  eleva- 
tion and  depression  of  the  ribs  and  sternum,  as  in  inspiration  and 
expiration.  From  the  direction  of  the  ribs,  when  their  anterior  part  is 
raised  they  assume  a  more  horizontal  position,  and  the  diameter  of  the 
chest  is  increased. 

The  thorax  is  more  ovoidal  and  less  compressed  antero-posteriorly  in 
the  female  than  the  male.  Tight-lacing  makes  it  still  more  assume  the 
form  of  an  oval. 

THE  HIP  OR  INNOMINATE  BONES. 

The  Hip  or  Innominate  bones,1  though  included  in  the  account  of  the 
trunk,  really  belong  to  the  lower  extremities,  holding  the  same  relation 
to  them  that  the  shoulder  bones  do  to  the  upper  extremities.  In  the 
lower  animals  their  presence  is  observed  to  be  in  a  great  measure 
dependent  on  the  existence  of  hinder  extremities.2  Together  with  the 
sacrum,  they  constitute  the  pelvis,  which  incloses  a  portion  of  the  diges- 
tive and  genito-urinary  apparatus.  For  convenience  of  description  they 
are  viewed  as  consisting  of  three  parts  :  the  il'ium,  is'chium,  and  pu/bis, 
corresponding  with  the  original  divisions  of  the  bones  as  existing  in 
infancy. 

The  Il'ium3  is  a  broad,  thick  plate  forming  the  upper  part  of  the  hip 
bone.  Its  inner  side  presents  three  surfaces :  an  anterior,  broad,  smooth 
concavity,  called  the  il'iac  fos'sa  ;*  a  posterior,  uneven  surface,  partly 
devoted  to  articulation  with  the  sacrum,  and  partly  to  ligamentous 
attachment ;  and  an  inferior,  small,  nearly  plane  surface,  forming  part  of 
the  true  pelvis. 

The  outer  or  dorsal  surface  of  the  ilium  is  convex  at  its  fore  part,  and 
concave  behind.  It  is  marked  by  two  feeble  ridges,  called  the  superior 
and  inferior  curved  lines.5  The  space  between  them  gives  origin  to  the 
small  gluteal  muscle  ;  the  space  above  them  to  the  middle  gluteal  muscle, 
except  a  rough  surface  at  the  posterior  superior  part  of  the  bone,  which 
gives  attachment  to  the  great  gluteal  muscle. 

1  Ossa  innominata  ;    ossa   anonyma ;  3  Os   ilium  ;    os   ilei ;    ileum ;    ileon ; 
o.    coxarum;    o.   lateralia    pelvis;    the      haunch;  haunch  bone. 

haunch  bones.  *  Fossa  iliaca. 

2  In  some  animals  hip  bones  exist  -with-          5  Linese  arcuatse ;  1.  semicircularis  su- 
out  the  presence  of  limbs,  but  in  such      perior  et  inferior. 

cases  they  are  quite  rudimentary;  as  in 
the  dolphin,  whale,  and  glass  snake. 


122 


THE   SKELETON. 


The  upper  border,  or  crest  of  the  il'ium,1  is  thick  and  rounded,  and  is 
convex  and  sigmoid  in  its  course.     It  gives  attachment  to  the  broad 


FIG.  95. 


FIG.  96. 


INNER  VIEW  OF  THE  LEFT  HIP  OR  INNOMINATE  BONE. 
The  dotted  line  indicates  its  division  into  three 
parts :  1,  the  ilium,  2,  the  ischium,  and  3,  thepubis. 
(1,  iliac  fossa:)  4, crest  of  the  ilium;  5,  6,  anterior 
superior,  and  inferior  spinous  processes ;  7,  8,  pos- 
terior superior,  and  inferior  spinous  processes ;  9, 
articular  surface  for  the  sacrum ;  10,  rough  surface 
for  the  attachment  of  ligaments.  (2,  body  of  the 
pubis  :)  11,  symphyses  ;  12,  horizontal,  and  13,  de- 
scending ramus ;  14,  upper  border  of  the  body ;  15, 
spine  of  the  pubis ;  16,  pectineal  line.  (3,  plane  of 
the  ischium :)  17,  ramus  of  the  ischium ;  18,  tuber- 
osity;  19,  spine  of  the  ischium;  20,  ilio-pubic 
eminence;  21,  obturator  foramen;  22,  great  sciatic 
notch ;  23,  lesser  sciatic  notch. 


OUTER  VIEW  OF  THE  LEFT  HIP  OR  INNOMINATE  BONE 
1,  ilium;  2,  ischium;  3,  pubis.  (1,  dorsal  surface 
of  the  ilium  :)  4,  crest  of  the  ilium  ;  5,  6,  superior 
and  inferior  curved  lines  ;  7,  surface  of  the  great 
gluteal  muscle ;  8,  9,  anterior  superior,  and  inferior 
spinous  processes ;  10,  11,  posterior  superior,  and 
inferior  spinous  processes.  (2, body  of  the  ischium:) 
12,  spine  of  the  ischium ;  13,  great  sciatic  notch ; 
14,  lesser  sciatic  notch ;  15,  tuberosity  of  the  is- 
chium ;  16,  ramus  of  the  ischium.  (3,  body  of  the 
pubis :)  17,  horizontal  ramus  of  the  pubis ;  18,  de- 
scending ramus;  19,  acetabulum;  20,  obturator 
foramen. 


muscles  of  the  abdomen,  and  terminates  at  each  end  in  a  prominence, 
called  the  anterior  superior,  and  posterior  superior  spi'nous  proc'ess,2 
Below  these  processes  is  a  notch,  succeeded  by  the  anterior  inferior, 
and  posterior  inferior  spi'nous  proc'ess.3  Following  these  processes 
are  other  notches  :  one  anteriorly,  terminated  below  by  the  ilio-pubic 
eminence ;  the  other  posteriorly  being  the  great  sciat'ic  notch.4 

1  Crista  ilei.  3  P.  s.  ant.  inf.  et  post,  inf.;  spina  ant. 

2  Processus  spinosus  ant.  sup.  et  post.       inf.  et  post.  inf. 

sup.;  spina  ant.  sup.  et  post.  sup.  4  Incisura  ischiadica  major;  incisura 

iliaca;  part  of  the  sacro-sciatic  notch. 


THE   SKELETON.  123 

The  Is'chium1  forms  the  inferior  part  of  the  hip  bone,  and  consists  of 
a  body  and  a  ramus,  united  in  the  form  of  a  hook.  The  body2  is  the 
posterior  thicker  portion  joining  the  ilium.  It  is  trilateral,  one  side 
looking  outward,  another  inward,  and  the  third  backward.  Below,  it 
forms  a  strong  prominence,  the  tuberos'ity,3  upon  which  we  sit,  and  which 
gives  origin  to  the  flexor  muscles  of  the  back  of  the  thigh.  Behind,  the 
ischium  possesses  a  strong  process,  the  spine,4  which  separates  the 
greater  sciat'ic  notch5  above  from  the  lesser  sciat'ic  notch6  below. 

The  ra'mus7  of  the  ischium  proceeds  from  the  lower  extremity  of  the 
body  upward  and  forward  to  the  pubis.  It  presents  an  inner  and  an 
outer  surface,  and  an  anterior  thick  border,  which  gives  attachment  to 
the  crus  of  the  penis. 

The  Pu/bis8  is  situated  at  the  anterior  part  of  the  hip  bone,  and  con- 
sists of  a  body  and  two  ra'mi  or  branches.  The  body  is  the  inner  ex- 
panded part,  flattened  before  and  behind,  and  having  at  its  inner  border 
an  uneven  articular  surface,  forming  part  of  the  sym/physis,  or  junction  of 
both  pubes.  The  upper  part  of  the  body  forms  an  obtuse  ridge9  termin- 
ating externally  in  a  small  eminence,  the  spine,10  which  gives  attachment 
to  the  lower  end  of  Poupart's  ligament. 

The  horizontal  ra'mus  of  the  pubis  proceeds  outward  from  the  body, 
and  at  its  junction  with  the  ilium  forms  the  il'io-pu/bic  eminence.11  It  is 
three  sided,  and  presents  three  margins,  of  which  one  is  inferior,  another 
is  obtuse  and  proceeds  from  the  spine  of  the  pubis  outwardly  to  the 
acetabulum,  and  the  third  is  sharp  and  is  called  the  pecti'neal  line,12 
This  proceeds  from  the  spine  of  the  pubis  to  the  inner  side  of  the  ilio- 
pubic  eminence,  and  at  its  commencement  gives  attachment  to  Gimber- 
nat's  ligament. 

The  descending1  ra'nms  of  the  pubis  proceeds  outward  and  downward 
to  join  the  ramus  of  the  ischium.  It  is  small  and  flattened  from  without 
inward. 

Having  described  the  separate  divisions  of  the  hip  bones,  it  remains  to 
point  out  some  anatomical  characters  formed  by  their  conjunction. 

At  the  union  of  the  three  pieces  of  the  hip  bone,  externally  there  is 

1  Os   ischii;    os   coxendicis;    ischion ;  8  Os  pubis;  os  pectinis;  pecten  ;  epis- 
huckle  bone ;  seat  bone.  chion. 

2  Ramus  descendens.  »  Crest ;  crista  pubis. 

3  Tuberositas  or  tuber  ischii ;  os  seden-  10  Tuberosity  of  the  pubis ;  tuberculum 
tarium.  pubicum ;  spina  pubis. 

4  Spina  ischii :  spinous  process.  n  Ilio-pectineal  protuberance ;    tuber- 
6  Incisura  ischiadica  major.                         culum  ilio-pubicum ;  tub.  ilio-pectineum. 

6  In.  isch.  minor;  luna  Albini.  12  Crista;  pecten;  linea  pectinea;  cris- 

7  Ramus  ascendens.  ta  ilio-pectinea. 


124  THE   SKELETON. 

situated  a  hemispherical  or  cup- shaped  cavity,  the  acetaVulum,1  for 
articulation  with  the  head  of  the  thigh  bone.  To  it,  the  pubis  contributes 
one-fifth,  and  the  ilium  and  ischium  contribute  each  about  two-fifths. 
It  is  bounded  by  a  prominent  margin,2  except  internally,  where  it  is 
deeply  notched.3  The  greater  part  of  the  surface  of  the  acetabulum  is 
smooth  and  covered  with  cartilage,  but  at  its  bottom  there  is  an  irregular 
pit,4  communicating  with  the  notch  of  its  margin,  which  is  occupied  by  a 
cushion  of  fat. 

In  advance  of  the  acetabulum,  between  the  pubis  and  ischium,  is  a 
large  hole,  the  obtura'tor  fora'men,5  which  is  closed  by  a  fibrous  mem- 
brane. It  is  oval,  with  a  tendency  to  assume  a  trilateral  form,  especially 
in  the  female. 

Above  the  position  of  the  acetabulum  is  the  il'io-pu/bic  emi'nence,6 
corresponding  with  the  union  of  the  horizontal  ramus  of  the  pubis 
with  the  ilium.  To  the  inner  side  of  this  eminence  there  proceeds  for- 
ward and  backward  the  ilio-pectineal  line,  which  separates  the  true  and 
false  pelvis. 

Internal  to  the  position  of  the  acetabulum,  within  the  pelvis,  there  is 
a  vertical  surface  formed  by  the  ilium  and  ischium,  and  called  by  obstet- 
ricians the  plane  of  the  is'chmm,  Behind  it,  formed  between  the  poste- 
rior inferior  spinous  process  of  the  ilium  and  the  spine  of  the  ischium,  is 
the  great  sciatic  notch. 

The  hip  bone  is  composed  of  spongy  substance  with  a  moderately  thick 
investment  of  compact  substance,  which  is  perforated  in  many  places 
with  large  foramina  for  nutritious  blood-vessels.  Frequently  the  two 
plates  of  compact  substance  come  into  contact  at  the  middle  of  the  iliac 
fossa,  and  in  this  position  are  so  thin  as  to  be  translucent. 

The  hip  bone  is  ossified  from  three  principal  pieces,  corresponding  with 
its  divisions  indicated,  and  four  epiphyses.  Ossification  commences  early 
in  foetal  life,  and  is  not  completed  until  after  adult  age.  The  epiphyses, 
which  begin  to  appear  subsequent  to  puberty,  consist  of  one  for  the  crest 
of  the  ilium,  another  for  the  tuberosity,  and  small  ones  for  the  anterior 
inferior  spinous  process  and  the  pubic  symphysis. 

1  Cotyle ;  cotyloid  cavity  ;  fossa  coty-  5  F.  obturatum   or   obturatorium ;    f. 
loidea;  sinus  coxae  ;  acetabulum  pyxis.  ovale;  f.  thyroideum;  f.  infra-pubianum; 

2  Supercilium  acetabuli.  f.  amplum  pelvis. 

3  Incisura  acetabuli.  6  Ilio-pectineal  eminence. 

4  Fossa  acetabuli. 


THE   SKELETON. 


125 


ARTICULATIONS  OF  THE  HIP  BONES. 

The  hip  bones  are  immovably  articulated  together  and  with  the  sacrum 
by  means  of  fibre-cartilaginous  plates  and  strong  ligaments. 

The  Pu/bic  sym'physis1  is  formed  by  the  conjunction  of  the  pubes 
through  a  thick  plate  of  fibro-cartilage,  as  in  the  union  of  the  vertebral 
bodies.  It  is  strengthened  by  fibrous  bands  passing  from  one  bone  to  the 
other,  constituting  the  pu'bic  lig'aments,  which  are  named,  from  their 
relative  position  to  the  symphysis,  anterior,  posterior,  etc.  The  inferior 
or  sub-pubic  ligament2  is  the  strongest. 

FIG.  98. 
FIG.  97. 


LIGAMENTS  OF  THE  PELVIS  AND  HIP  JOINT.  1,  pos- 
terior sacro-iliac  ligament;  2,  great  sacro-sciatic 
ligament ;  3,  small  sacro-sciatic  ligament ;  4,  great 
sacro-sciatic  foramen ;  5,  small  sacro-sciatic  fora- 
men; 6,  cotyloid  ligament  surrounding  the  border 
of  the  acetabulum ;  7,  round  ligament ;  8,  cut  edge 
of  the  capsular  ligament ;  9,  obturator  membrane. 


LIGAMENTS  OF  THE  PELVIS  AND  HIP  JOINT.  1,  lower 
part  of  the  anterior  vertebral  ligament ;  2,  pubic 
symphysis;  3,  ilio-lumbar  ligament;  4,  sacro-iliac 
symphysis,  with  the  anterior  sacro-iliac  ligament ; 
5,  obturator  membrane ;  6,  edge  of  the  tendon  of  the 
external  oblique  muscle  of  the  abdomen,  techni- 
cally named  Poupart's  ligament ;  7,  extension  of  the 
latter  along  the  pectineal  line  named  Gimbernat'a 
ligament;  8,  capsular  ligament  of  the  hip  joint;  9, 
a  strong  accessory  band  of  the  latter  ligament. 

The  Obturator  mem'brane3  is  a  fibrous  structure,  closing  the  obturator 
foramen,  except  at  its  upper  and  outer  part,  where  there  is  an  orifice* 
for  the  passage  of  the  obturator  vessels  and  nerve.  The  surfaces  of  the 
membrane  give  origin  to  the  obturator  muscles. 

The  Sa'cro-il'iac  sym'physis5  is  formed  by  the  union  of  the  corre- 


1  Symphysis  pubis.  2  Lig.  arcuatum. 

3  Membrana  obturatoria ;  ligamentum  obturatorium ;  sub-pubic  membrane. 

5  Symphysis  sacro-iliaca. 


*  Canalis  obturatorius. 


126  THE   SKELETON. 

spending  articular  surfaces  of  the  ilium  and  sacrum  through  means  of 
fibro-cartilage,  which  is  separable  by  force  into  two  plates  adhering  one 
to  each  bone.  The  joint  is  strengthened  by  the  anterior  and  posterior 
sa'cro-il'iac  lig'aments.1  The  former  consists  of  short  bands  uniting  the 
contiguous  bones  in  front  of  the  symphysis.  The  latter  is  composed  of 
strong  bands  passing  transversely  and  obliquely  from  the  posterior  spi- 
nous  processes  and  contiguous  uneven  surface  of  the  ilium  to  the  corre- 
sponding surface  of  the  sacrum,  behind  the  symphysis. 

The  Il/io-lum/bar  lig'ament2  is  a  fibrous  band  springing  from  the  end 
of  the  transverse  process  of  the  last  lumbar  vertebra,  and  expanding 
outwardly  to  be  attached  to  the  posterior  part  of  the  crest  of  the  ilium. 

The  Great  sa'cro-sciat/ic  lig'ament3  is  a  strong  triangular  band 
attached  by  its  base  to  the  posterior  inferior  spinous  process  of  the  ilium 
and  the  margin  below  of  the  sacrum  and  coccyx,  and  by  its  apex  to  the 
inner  margin  of  the  tuberosity  of  the  ischium,  along  which  it  presents  a 
narrow  expansion. 

The  Small  sa'cro-sciat'ic  lig'ament,4  IGSS  strong  than  the  preceding, 
springs  in  conjunction  with  it  from  the  margin  of  the  sacrum  and  coccyx, 
and  converges  to  be  attached  to  the  spine  of  the  ischium. 

By  means  of  the  sacro-sciatic  ligaments,  the  sciatic  notches  are  con- 
verted into  the  great  and  small  sciatic  fora'mma,5  The  former  is  oval 
and  transmits  the  pyramidal  muscle,  the  sciatic  nerve,  and  the  gluteal, 
pudic,  and  ischiatic  vessels  and  nerves.  The  latter  foramen  is  more  tri- 
lateral, and  transmits  the  obturator  muscle,  and  the  internal  pudic  vessels 
and  nerve. 

THE  PELVIS. 

The  Pel'vis6  is  the  basin-like  portion  of  the  trunk  formed  by  the  hip 
bones,  the  sacrum,  and  the  coccyx.  It  is  situated  in  an  oblique  position 
from  the  vertebral  column,  downward  and  backward,  so  that  the  end  of 
the  coccyx  is  nearly  on  a  level  with  the  middle  of  the  pubic  symphysis. 

By  means  of  the  il'io-pectine'al  line,7  and  the  upper  projecting  part  of 
the  sacrum,  called  its  promontory,8  the  pelvis  is  divided  into  the  superior 
or  false,  and  the  inferior  or  true  pel'vis. 

1  Lig.  sacro-iliacum  ant.  et  post. ;  the  5  Foramina  sciatica,  or  ischiatica,  or 
posterior  consisting  of  the  lig.  sacro-ili-  ischiadicum  majus  et  minus,  or  major 
acum  longum  et  breve.  et  minor. 

2  L.  ilio-lumbale.  6  Choana;  pyclos  ;  lecane. 

3  L.  sacro-ischiaticum  majus ;  1.  posti-  7  Linea  arcuata  interna ;  1.  innomina- 
cus  ;  1.  tuberoso-sacrum.  ta ;  1.  terminalis. 

4  Lig.  sacro-ischiaticum  minus,  or  an-  8  Promontorium. 
ticus,  or  internum;  1.  spinoso-sacrum. 


THE   SKELETON. 


127 


FIG.  99. 


The  superior  pel'vis1  is  formed  on  each  side  by  the  ilium,  and  is  com- 
pleted by  the  lumbar  verte- 
brae and  the  soft  walls  of 
the  abdomen. 

The  inferior  pel'vis2 
is  composed  of  the  pubes 
and  ischia,  the  sacrum  and 
coccyx.  Its  cavity  is 
curved  cylindrical,  nar- 
rowing below  and  becom- 
ing deeper  from  before 
backward.  Its  inlet  and 
outlet  are  also  called  the 
superior  and  inferior 
straits,  the  ideal  planes  of 
which  converge  anterior- 


The  superior  strait3 
corresponds  with  the  ilio- 
pectineal  line  and  pro- 
montory of  the  sacrum, 


FRONT  VIEW  OF  A  FEMALE  PELVIS.  1,  last  lumbar  vertebra ;  2, 
intervertebral  ligaments;  3,  sacrum,  the  figure  being  placed  on  its 
promontory ;  4,  transverse  lines,  indicating  the  original  separation 
of  the  sacrum  into  five  vertebral  segments ;  5,  end  of  the  coccyx ; 
6,  iliac  fossa;  7, 8,  anterior  superior,  ancl  inferior  spinous  processes; 
9,  acetabulum;  10,  its  notch  on  the  inner  side ;  11,  body  of  the  is- 


the     projection     Of    Which     chium;  12,  tuberosity  of  the  ischium;  13,  spine  of  the  ischium, 

,.„  seen  through  the  obturator  foramen;  14,  body  of  the  pubis;  15, 

gives   It   a  COrdlform    OUt-     Bymphy8i8  of  the  pubis;  16,  arch  of  the  pubis;  17,  upper  part 


m1       .     /.     •  j_       •  j_  A.  • 

The  inferior  strait4  is 


of  the  body  of  the  pubis  ;  18,  spiue  of  the  pubis  ;  19,  pectineal 
line  ;  20,  ilio-pubic  eminence  ;  21,  great  sacro-sciatic  notch. 


bounded  by  three  prominences,  separated  by  as  many  notches.  Of  the 
prominences,  two  are  lateral  and  correspond  with  the  tuberosities  of  the 
ischia,  and  the  other  is  formed  by  the  sacrum  and  coccyx.  Of  the 
notches,  one  is  the  pu'bic  arch,5  bounded  on  each  side  by  the  rami  of  the 
ischium  and  pubis.  It  is  triangular,  and  has  for  its  apex  the  symphysis 
of  the  pubes.  The  other  notches,  called  from  their  position  sa'cro-sci- 
at'ic,  by  means  of  ligaments  of  the  same  name  are  converted  into  fora- 
mina likewise  distinguished  by  the  same  designation. 

The  axis  of  the  inferior  pelvis  constitutes  a  curved  line6  passing  out 
at  the  centre  of  the  straits. 


1  The  great,  or  greater  pelvis ;  false 
pelvis ;  labrum  pelvis. 

2  The  small,  or  lesser  pelvis ;  pelvis 
minor;  p.  vera. 

3  Brim  of  the  pelvis ;  apertura  pelvis 
superior ;    introitus  ;  angustia   abdomi- 
nalis ;  upper  opening. 


4  Apertura  pelvis  inferior ;  lower  open- 
ing ;  exitus ;  angustia  perinaealis. 

5  Arcus   ossium  pubis ;    arch   of   the 
pubis. 

6  The  curve  of  Carus. 


128 


THE   SKELETON. 


In  the  infant  the  capacity  of  the  inferior  pelvis  is  so  small  that  the 
urinary  bladder  for  the  most  part  occupies  the  space,  of  the  superior 
pelvis. 

SEXUAL  DIFFERENCES  OF  THE  PELVIS. 

The  sexual  differences  of  the  pelvis  are  greater  than  in  any  other  por- 
tion of  the  skeleton.  In  the  female  the  pelvis  is  more  capacious  in  its 
breadth  and  less  deep  than  in  the  male.  In  consequence  of  this  most 
important  difference,  the  birth  of  the  infant  is  easier  and  quicker  than  it 
could  be  under  the  opposite  conditions.  The  bones  of  the  pelvis  are 
thinner  and  less  marked  by  muscular  attachments.  The  sides  of  the 
superior  pelvis,  formed  by  the  ilia,  are  more  expanded.  The  promontory 
of  the  sacrum  is  less  projecting,  and  in  consequence  of  this  difference 
the  superior  strait  is  less  cordiform  or  is  more  oval.  The  cavity  of  the 
inferior  pelvis  is  more  uniformly  cylindrical,  from  the  ischia  converging 
less  below  or  from  their  being  more  parallel.  The  depth  of  the  inferior 
pelvis  is  less,  but  its  breadth  is  greater.  The  diminution  in  depth 
depends  on  the  less  extent  of  the  ischia.  The  sub-pubic  arch  is  lower, 
wider,  more  obtuse  at  the  summit,  and  less  everted  at  the  sides.  The 
sacrum  and  coccyx  are  shorter  and  wider;  the  ilio-pectineal  line  is 
longer ;  and  the  obturator  foramen  is  more  trilateral.  The  following 
table  gives  the  comparative  measurements  of  the  inferior  pelvis  in  the 
two  sexes : — 

SUPERIOR  STRAIT.  MALE.  FEMALE. 

Antero-posterior  diameter1         .....      4    inches.      4|  inches. 

Transverse  diameter 4|        "          5^      " 

Oblique  diameter        .        .        .        .        '.        .        .4*       "          4|      " 

Circumference 15         "  16*      " 

CAVITY. 

Antero-posterior  diameter         .        .        .        . 

Transverse  diameter 

Depth  at  the  pubic  symphysis 

Depth  posteriorly 

Depth  at  the  sides 

Circumference 

INFERIOR  STRAIT. 

Antero-posterior  diameter ;  from  the  mobility  of  the 

coccyx  capable  of  being  extended  an  additional 

inch    .........      3|  inches.      4^  inches. 

Transverse  diameter .......      3^        "          4^      " 

At  the  approach  of  the  end  of  pregnancy,  the  symphyses  of  the  pelvis 
undergo  a  slight  degree  of  relaxation,  which  facilitates  child-birth. 


4^  inches.       4*  inches. 
4          "          4*      " 

If  1*       " 
5±         "          5 
4          "          3*      " 

13*        "  15*      " 


Conjugate  diameter. 


THE  SKELETON.  129 


THE   UPPER  EXTREMITIES. 

The  Upper  extremities  are  suspended  from  the  thorax  at  the  sides  of 
the  skeleton,  with  which  they  articulate  only  by  the  inner  end  of  the  clav- 
icle, so  that  when  this  bone  is  absent,  as  in  many  quadrupeds,  the  fore 
legs  have  no  ligamentous  union  with  the  other  part  of  the  skeleton. 

Each  upper  extremity  consists  of  two  bones  to  the  shoulder,  one  to  the 
arm,  two  to  the  forearm,  and  twenty-nine  to  the  wrist  and  hand. 

BONES  OF  THE  SHOULDER. 

The  two  bones  of  the  shoulder  are  the  clavicle  and  scapula.  By  means 
of  the  former  it  is  connected  with  the  sternum  and  first  rib,  and  by  means 
of  the  latter  with  the  arm  bone. 

THE  CLAYICLE. 

The  Clavicle1  or  collar  bone  is  situated  in  front  of  the  upper  part  of 
the  thorax,  extended  transversely  between  the  sternum  and  the  acromion 
of  the  scapula.  It  is  cylindroid,  with  a  sigmoid  curve;  is  more  curved 
and  robust  in  the  male,  and  most  so  in  vigorous  persons. 

The  ster'nal  end2  is  thickened,  and  presents  an  irregular  triangular 
surface,  partly  for  articu- 
lation with  the  sternum, 
and  partly  for  the  attach- 
ment of  ligaments.  The 
acro'mial  end3  is  com- 
pressed from  above  down-  CL^CLE  OF  THE RIGHT  ^  upper  yjew  1?  gternal  end; 

Ward,  and  has  a  Small  ar-    tion  which  joins  the  cartilage  of  the  first  rib;  3,  anterior  convexity 

ticular  rSUrface  for  Union  and  line  °f  attachment  of  the  great  pectoral  muscle;  4,  upper 
surface  of  the  acromial  end;  5,  its  articular  surface;  6,  anterior 

With  the  acromion.  concavity,  giving  attachment  to  the  deltoid  muscle;  7,  posterior 

The  Upper  Surface  Of  convexity>  giving  attachment  to  the  trapezius  muscle;  8,  position 
of  origin  of  the  sterno-mastoid  muscle. 

the    clavicle    is    covered 

only  by  the  skin  and  subcutaneous  fascia.  The  lower  surface  is  directed 
toward  the  first  rib  and  the  coracoid  process  of  the  scapula,  and  is 
marked  by  the  ligamentous  attachments  with  these  bones.  In  the  curva- 
tures of  the  clavicle,  the  convexity  of  its  acromial  extremity  is  directed 
backward  ;  that  of  the  sternal  extremity  forward. 

1  Clavicula;    clavis;   furcula;  ligula;  2  Extremitas  sternalis. 

osjuguli;  jugulum;  cleidion.  8  Extremitas  acromialis. 


130  THE  SKELETON. 

The  clavicle  is  a  most  important  agent  in  maintaining  the  position  of 
the  upper  extremity ;  removing  the  shoulder  joint  a  convenient  distance 
from  the  thorax,  thus  contributing  to  the  greater  range  and  freedom  of 
movement  of  the  limb.  If  it  is  removed  or  broken,  the  shoulder  is  de- 
pressed, and  the  head  of  the  arm  bone  falls  against  the  side  of  the  tho- 
rax and  is  much  restricted  in  its  movements. 

In  animals  which  use  the  fore  legs  only  for  support,  the  clavicle  does 
not  exist,  as  in  the  ruminants  and  the  horse ;  its  degree  of  development 
is  intimately  related  with  the  freedom  of  movement  of  the  fore  extremi- 
ties of  other  animals.  Thus  it  is  well  developed  in  squirrels,  bats,  and 
birds,  and  is  feebly  developed  in  dogs  and  cats. 


THE  SCAPULA. 

The  Scap'ula1  or  shoulder  blade  is  situated  at  the  upper  back  part  of 
the  thorax,  extending  from  the  position  of  the  second  to  the  seventh  rib. 
It  is  broad,  flat,  thin,  and  triangular,  and  presents  two  surfaces,  three 
borders,  three  angles,  and  three  processes. 

Of  the  surfaces,  the  anterior2  forms  the  shallow  subscap'ular  fos'sa,3 
which  is  crossed  by  ridges,4  and  gives  attachment  to  the  subscapular  mus- 
cle. The  posterior  surface5  is  divided  by  a  projecting  plate,  the  spine, 
into  two  unequal  parts,  of  which  the  upper  and  smaller  is  called  the 
su'pra-spi'nous  fos'sa,6  and  the  lower  the  in'fra-spi'nous  fossa;7  both 
being  occupied  by  like-named  muscles. 

Of  the  borders,  the  superior8  is  the  shortest  and  thinnest.  At  its 
outer  part  is  the  cor'acoid  notch,9  which  is  converted  by  a  transverse 
fibrous  band,  the  cor'acoid  lig-ament,10  into  the  cor'acoid  fora 'men.11 
The  posterior  border12  or  base  is  the  longest,  is  irregularly  convex  in 
its  course,  and  gives  attachment  to  muscles.  The  inferior  border13 
inclines  toward  the  axilla,  and  is  thick  and  partially  grooved.  At  its 
upper  part  is  a  rough  impression  produced  by  the  attachment  of  the  long 
head  of  the  triceps  extensor  muscle. 


1  Scapulum ;  spatula ;   scaptula  ;    pla-  6  Fossa  supra-spinatus. 
ta;    omoplata;    pterygium;    chelonium;  7  F.  infra-spinatus. 

epinotion;  os  latum  huireri;  scutum  tho-  8  Costa  superior  ;  cervical  border, 

racis;  latitude  humeri ;  blade  bone;  plate  9  Incisura  coracoidea  ;  i.  scapulae  ;  lu- 

bone;  spade  bone;  shield  bone.  nula;  supra-scapular  notch. 

2  Venter.  10  Lig-  coracoideum. 

3  Fossa  subscapularis.  u  Foramen  coracoideum. 
*  Costse  scapulares.  12  Vertebral  border. 
sDorsum;     dorsal    surface;     testudo  13  Costa  inferior ;  axillary  border. 

scapulae. 


THE  SKELETON. 


131 


Of  the  angles,  the  superior  is  thin,  and  is  formed  at  the  conjunction  of 
the  upper  border  and  base.     The  inferior  angle  is  thick,  and  expanded 


FIG.  101. 


FIG.  102. 


THE  SCAPULA  OF  THE  LEFT  SIDE,  posterior  view.  1, 
supra-spinous  fossa;  2,  infra-spinous  fossa;  3,  supe- 
rior border;  4,  coracoid  notch;  5,  inferior  border; 
6,  glenoid  cavity;  7,  inferior  angle;  8,  neck  of  the 
scapula;  9,  posterior  border  or  base ;  10,  spine;  11, 
its  triangular  commencement,  upon  which  the  ten- 
don of  the  trapczius  muscle  moves ;  12,  acromion  ; 
13,  one  of  the  nutritious  foramina;  14,  coracoid 
process. 


ANTERIOR  VIEW  OF  THE  SCAPULA.  1,  ridges  cross- 
ing the  subscapular  fossa ;  2,  upper  boundary  of  the 
latter ;  3,  superior  border ;  4,  superior  angle ;  5,  co- 
racoid notch;  6,  coracoid  process;  7,  acromion; 
8,  spine  of  the  scapula;  9,  articular  surface  for 
the  clavicle ;  10,  glenoid  cavity ;  11,  elevated  bor- 
der of  the  same;  12,  neck;  13,  inferior  border; 
14,  inferior  angle ;  15,  base ;  16,  position  at  which 
the  spine  commences  posteriorly. 


at  its  outer  part,  where  it  gives  origin  to  the  greater  terete  muscle.  The 
external  angle1  is  massive,  and  supports  a  vertically  ovate,  shallow,  con- 
cave surface,  the  gle'noid  cavity,2  forming  part  of  the  shoulder  joint. 
The  cavity  has  an  obtuse  prominent  border,  and  is  supported  by  a  nar- 
rowed portion  of  the  bone,  named  the  neck  of  the  scap'ula,3 

Of  the  processes,  the  spine*  is  the  most  conspicuous,  consisting  of  a 
strong  triangular  plate  springing  backward  and  a  little  upward  from  the 
posterior  surface  of  the  scapula  and  separating  the  supra-  and  infra-spi- 
nous fossae.  Its  anterior  border  curves  over  the  neck  of  the  scapula,  and 
is  thick  and  rounded.  Its  posterior  border  commences  in  a  triangular 
expansion  at  the  base  of  the  bone,  is  thick  and  strong,  and  has  attached 


1  Corpus  scapulae. 

2  Cavitas,  or  fossa  glenoidea ;  acetabu- 
lum  huraeri ;  cavitas  humeri  glenoicles ; 
omocotyle;  entyposis. 


8  Cervix,  or  collum  scapulj 
*  Spina  scapulae. 


132  THE  SKELETON. 

the  trapezius  and  latissimus  muscles.  The  angle  of  conjunction  of  the 
anterior  and  posterior  borders  is  prolonged  outwardly  and  expanded  into 
a  broad  process,  the  acro'mion,1  which  forms  the  summit  of  the  shoulder 
and  overhangs  the  joint. 

From  above  the  glenoid  cavity  the  strong  hook-like  cor'acoid  proc'ess2 
curves  outwardly  toward  the  front  of  the  shoulder  joint.  Its  end  and 
base  are  tuberous  for  the  attachment  of  ligaments,  and  behind  it  is  the 
coracoid  notch. 

The  scapula  is  almost  completely  enveloped  in  muscles,  and  it  is  only 
the  posterior  border  of  its  spine  and  the  acromion  that  can  be  readily  felt 
beneath  the  skin,  and  which  become  conspicuous  in  emaciated  persons.  The 
processes  and  borders  of  the  bone  are  for  the  most  part  thick  and  strong. 
In  the  position  of  the  infra-  and  supra-spinous  fossa3  the  bone  is  usually 
thin  and  translucent,  and  sometimes  is  even  imperfect.  At  the  base  of 
the  spine  there  are  usually  from  one  to  three  large  nutritious  foramina. 

BONES  OF  THE  AKM  AND  FOREARM. 

A  single  bone,  the  humerus,  enters  into  the  constitution  of  the  arm.3 
It  joins  the  glenoid  cavity  of  the  scapula,  from  which  it  extends  verti- 
cally, with  a  slight  inclination  inward,  to  join  the  bones  of  the  forearm.4 
These  are  the  radius  and  ulna,  which  lie  side  by  side,  separated  by  an 
interspace,  and  extend  downward  to  the  wrist  with  a  slight  inclination 
outward  and  forward. 

THE  HUMERUS. 

The  Hu/merus5  or  arm  bone  is  long  and  cylindroid,  and  presents  for 
special  examination  its  shaft  and  extremities. 

The  shaft  or  body  is  rounded  at  its  upper,  and  trilateral  at  its 
lower  part.  The  posterior  surface  is  smooth,  rounded  above  and  flat- 
tened below,  and  is  occupied  its  entire  extent  by  the  triceps  extensor 
muscle.  The  anterior  surface  below  inclines  on  each  side  to  a  ridge 
separating  it  from  the  posterior  surface,  and  is  occupied  by  the  brachial 
muscle.  Near  the  middle  of  the  shaft  internally,  is  a  slight  roughness 


1  Aeromium ;  acrocolium ;  os  acromii ;  3  Brachium. 
humerus,  or  armus  summus  ;  caput  scap-  *  Antibrachium. 

ulse  ;  mucro  humeri ;  rostrum  porcinum.  5  Os  brachii ;  os  brachiale ;  os  humeri ; 

2  Processus  coracoideus  ;  p.  uncinatus;  os     adjutorium;     brachium  ;    lacertus; 
p.  cornicularis ;  p.  anchoralis ;  p.  rostri-  shoulder  bone. 

formis ;  p.  ancyroides. 


THE  SKELETON. 


133 


produced  by  the  insertion  of  the  coraco-brachial  muscle.     Above  the 

middle,  on  the  outer  aspect,  is  a  broad,  superfi-  ^      ^ 

cial,  rough  eminence,1  into  which  the  deltoid 

muscle  is  inserted.      Between   this   eminence 

and  the  ridge  descending  to  the  outer  condyle, 

the  shaft  presents  a  slight  spiral  tract,  from 

its  upper  back  part   outwardly  to   its  lower 

front  part,  indicating  the  course  of  the  supe- 

rior  profound  artery  and   the  musculo-spiral 

nerve.     At  the  upper  third  of  the   shaft  is 

a  longitudinal  gutter,  the  bicip'ital  groove,2 

which  accommodates  the  tendon  of  the  long 

head  of  the  biceps  muscle.      The   groove  is 

bounded  by  ridges,3  of  which  the  outer  one 

gives  attachment  to  the  great  pectoral  muscle, 

and  the  inner  one  to  the  latissimus  and  greater 

terete  muscles. 

The  upper  extremity  of  the  bone  expands 
and  supports  a  large  hemispherical  eminence, 
the  head,4  which  is  directed  backward  and 
inward,  and  forms  part  of  the  shoulder  joint. 
To  the  outer  side  of  the  head,  and  separated 
from  it  by  a  slight  groove  corresponding  with 

the    neck5    Of    the    bone,  are    the    tliberOS'itieS,    4,  greater  tuberosity;  5,  lesser  tub- 

separated  from  eaeh  other  by  the  bicipital  S^y^'SEfc 

groove.     The  greater  tuberosity6  is  external  ing  attachment  to  muscles  ;  9,  posi- 

to  the  other,  and  at  its  upper  part  presents  £t£^^££ 

three  impressions  for  the  attachment  of  the  men;  11,  articular  eminence  for  the 

supra-  and  infra-spinous  and  lesser  terete  mus-  radius'  12'  trochlea  for  the  ulna;  13> 

x  •  14,  external  and  internal  condyles  ; 

cles.  The  smaller  tuberosity7  gives  attachment  15, 
to  the  subscapular  muscle. 

Surgical  writers   apply  the  term  neck8  to 
that  portion  of  the  bone  just  below  the  tuberosities,  which,  though  not 
anatomically  correct,  is  convenient  for  practical  purposes. 

The  lower  extremity  of  the  humerus  is  expanded  laterally,  and  pre- 
sents at  the  sides   prominent  tuberosities,  the  con'dyles,  from  which 


condyioid  ridges  ascending 
from  the  latter;  17'  f°88a  for  the 

coronoid  process  of  the  ulna. 


1  Tuberositas. 

2  Sulcus,  or  fossa  bicipitalis  ;    sulcus 
intertubercularis. 

3  Bicipital  ridges ;  spina  tuberculi  ma- 
joris  et  minoris. 


4  Caput. 

5  Cervix  humeri  anatomicum. 

6  Tuberculum  majus. 

7  Tuberculum  minus. 

8  Cervix  humeri  chirurgicum. 


134  THE  SKELETON. 

ascend  the  con'dyloid  ridges.  The  internal  con'dyle1  is  more  promi- 
nent than  the  other,  gives  attachment  to  the  internal  lateral  ligament  of 
the  elbow  joint,  and  gives  origin  to  the  short  pronator  and  most  of  the 
flexor  muscles  on  the  inner  part  of  %the  forearm.  The  external  con'- 
dyle2 gives  attachment  to  the  external  lateral  ligament,  and  the  ridge 
above  it,  more  prominent  than  the  opposite  one,  gives  origin  to  the 
supinator  and  extensor  muscles  on  the  outer  and  back  part  of  the 
forearm. 

Between  the  condyles  is  the  articular  surface  for  the  bones  of  the  fore- 
arm. The  outer  portion  of  this  surface  is"  a  convex  eminence3  adapted 
to  the  head  of  the  radius.  The  inner  portion,  the  troch/lea,  as  expressed 
by  the  name,  is  pulley-like,  and  articulates  with  the  ulna.  Above  the 
front  of  the  trochlea  is  a  pit4  which  accommodates  the  point  of  the  coro- 
noid  process  of  the  ulna  in  the  flexion  of  the  forearm;  and  above  it 
posteriorly  is  a  more  extensive  fossa5,  which  receives  the  olecranon  in 
extension  of  the  forearm. 

The  canal  for  the  nutritious  artery  of  the  marrow  descends  at  the 
lower  third  of  the  shaft  internally. 

THE  ULNA. 

The  TJl'na6  occupies  the  inner  side  of  the  forearm,  and  is  a  little  longer 
than  the  radius.  It  is  prisnioid  in  form,  and  diminishes  toward  its  lower 
extremity. 

Its  shaft  presents  three  surfaces  separated  by  prominent  borders.  The 
anterior  surface  is  slightly  depressed,  and  gives  origin  to  the  deep  flexor 
of  the  fingers  The  inner  surface  above  is  expanded  for  the  origin  of 
the  latter  muscle,  and  below  is  rounded  and  subcutaneous.  The  posterior 
surface  above  presents  an  elongated,  shallow  depression,  which  accom- 
modates the  anconeus  muscle,  and  below  this  a  flattened  surface  for  the 
extensor  muscles  of  the  thumb.  Of  the  three  borders,  the  inner  two  are 
obtuse,  and  the  outer  one  is  acute  and  gives  attachment  to  the  inter- 
osseous  membrane. 

The  upper  extremity,  which  is  the  thickest  portion  of  the  ulna,  term- 
inates in  two  robust  processes  inclosing  the  articular  surface  for  the 


1  Condylus  interims ;  c.  flexorius.  5  Fovea    supra-trochlearis   posterior ; 

2  Condylus  extensus ;  c.  extensorius.  greater  sigmoid  cavity. 

3  Eminentia  capitata ;  capitellum  ;  the  6Cubitus;    focile  majus  or  inferius; 
little  head;  rotula.  canna  major  brachii;  os  cubiti  inferius; 

4  Fovea    supra-trochlearis     anterior;  cubit;  os   procubitale;    arundo   brachii 
lesser  sigmoid  cavity.  major;  olene. 


THE  SKELETON. 


135 


FIG.  104. 


humerus.  The  posterior  and  larger  process,  the  olec'ranon,1  is  on  a  line 
with  the  shaft  of  the  bone.  Its  upper  part  is  truncated  and  receives  the 
insertion  of  the  triceps  extensor  muscle.  Its  back  part  presents  a  tri- 
lateral surface,  which  is  subcutaneous.  The  cor'onoid  process2  projects 
from  the  front  of  the  bone,  and  is  roughened3  at  the  fore  part  of  its 
base  for  the  insertion  of  the  brachial  muscle. 

Between  the  olecranon  and  coronoid  processes  is  the  greater  sig'- 
moid  cavity,4  which  articulates  with  the  trochlea  of  the 
humerus.     Its  outer  side  is  continuous  with  the  lesser 
sig'moid  cavity,5  a  transverse  concave  surface,  which  ar- 
ticulates with  the  head  of  the  radius. 

The  lower  extremity  of  the  ulna  is  narrow  and  cylin- 
droid.  It  terminates  in  a  rounded  head  articulating 
with  the  radius,  and  a  coni- 
cal sty'loid  process,6  to  which 
is  attached  the  internal  lat- 
eral ligament  of  the  wrist. 
Between  the  styloid  proc- 
ess and  head  is  a  depression, 
into  which  is  inserted  a  fibro- 
cartilage  separating  the  ra- 
dio-ulnar  from  the  radio-car- 
pal articulation.  Behind  the 
styloid  process  is  a  groove 
which  transmits  the  tendon 
of  the  ulno-carpal  extensor. 


THE  TWO  BONES  OF  THE  LEFT  FORE- 
ARM, viewed  in  front;  the  ulna  to 
the  right  and  the  radius  to  the  left 
of  the  figure.  1,  shaft  of  the  ulna; 
2,  greater  sigmoid  cavity ;  3,  lesser 
sigmoid  cavity  articulating  with 
the  head  of  the  radius;  4,  olecra- 
non; 5,  coronoid  process;  6,  nutri- 
tious foramen ;  7,  sharp  ridges  of 
both  bones  of  the  forearm  for  the 
attachment  of  the  interosseous 
membrane;  8,  head  of  the  ulna; 
9,  styloid  process;  10,  shaft  of 
the  radius ;  11,  head  of  the  same ; 
12,  neck  ;  13,  tuberosity ;  14,  rough- 
ened attachment  of  the  terete  pro- 
nator  muscle;  15, carpal  extremity 
of  the  bone ;  16,  its  styloid  process. 


THE  RADIUS. 

The  Ra'dius7  is  placed  at  the  outer  side  of  the  ulna,  and  extends  a 
little  lower  in  the  forearm. 

Its  shaft  is  trilateral,  with  an  acute  border  internally  for  the  attach- 


1  Olecranon;    o.  mobile;    olecranum; 
acrolenion;  ancon;  processus  anconaeus; 
p.  uncinatus  ulnae  ;  glans  ulnae ;  corona 
ulnae;    corona  posterior  ulnae;    addita- 
mentum  necatum,  or  uncatum  ulnae ;  ver- 
tex cubiti;  patella  fixa;  rostrum  exter- 
num,  or  posterius ;  top  of  the  cubit. 

2  Processus  coronoideus. 

3  Tuberositas  ulnae. 


4  Cavitas  sigmoidea  major;    c.  lunata 
major;  semilunar  fossa:  olecranoid  cav- 

ity- 

5  Cavitas  sigmoidea  minor;    c.  lunata 
minor. 

6  Processus  styloideus. 

7  Manubrium  manus  ;  focile  minus,  or 
superius ;    additamentum  ulnae ;    canna 
minor ;   cercis ;  os  ad  cubitale ;  arunclo 
brachii  minor ;  parapechyon. 


136  THE  SKELETON. 

nient  of  the  interosseous  membrane.  The  external  surface  is  rounded, 
and  near  its  middle  is  impressed  by  the  insertion  of  the  terete  pronator 
muscle.  The  anterior  surface  is  flattened,  expands  below,  and  is  slightly 
grooved  at  the  middle  for  the  origin  of  the  long  flexor  of  the  thumb. 
The  posterior  surface  is  rounded  above,  and  is  flattened  below,  where  it 
accommodates  the  extensor  of  the  thumb. 

The  upper  extremity  of  the  bone  in  front  presents  a  rough  eminence, 
the  tuberos'ity,1  into  which  the  biceps  muscle  is  inserted.  Above  it  is 
the  neck,2  and  this  supports  a  discoidal  head,3  the  wide  margin  of  which 
articulates  with  the  ulna,  and  the  upper  concave  surface  with  the  humerus. 

The  lower  extremity  of  the  radius  is  its  thickest  portion.  In  front,  it 
is  broad  and  depressed,  and  bounded  below  by  a  prominent  ridge  giving 
attachment  to  the  capsular  ligament  of  the  wrist.  Behind,  it  is  irregu- 
larly convex,  and  exhibits  a  narrow  groove  separating  two  broad  ones, 
all  of  which  transmit  extensor  tendons.  Its  outer  side  presents  another 
broad  groove,  which  likewise  transmits  tendons.  Below  the  latter  groove 
is  a  pyramidal  eminence,  the  sty'loid  process,4  with  which  the  external 
lateral  ligament  of  the  wrist  is  connected.  On  the  inner  side  of  the 
lower  extremity  is  a  transverse  excavation,  the  semilunar  cavity,5  for 
articulation  with  the  head  of  the  ulna.  Below  is  a  large  concavity,  the 
carpal  articular  surface,6  which  is  divided  by  a  slight  ridge  into  two 
parts,  corresponding  with  the  position  of  the  scaphoid  and  lunar  bones. 

The  canal  for  the  nutritious  artery  of  the  marrow,  in  both  bones  of 
the  forearm,  ascends  from  the  front  of  their  upper  third. 

BONES  OF  THE  HAND. 

The  bones  of  the  hand  are  situated  in  the  same  general  plane  with 
those  of  the  forearm,  and  are  subdivided  into  those  of  the  carpus,  of 
which  there  are  eight ;  of  the  metacarpus,  of  which  there  are  five  ;  and 
of  the  fingers,  of  which  there  are  sixteen. 

BONES  OF  THE  CAEPUS. 

The  Carpal  bones,'  or  those  of  the  carpus  or  wrist,8  eight  in  number, 
are  arranged  in  two  rows,  of  which  one  joins  the  forearm,  the  other  the 
metacarpus.  Those  of  the  first  row,  indicated  from  the  outer  side  of 

1  Tuberositas ;  bicipital  tuberosity.  5  Incisura  semilunaris. 

2  Cervix;  collum.  6  Fossa  scaphoidea;  f.  navicularis. 

3  Caput.  7  Ossa  carpi. 

4  Processus  styloideus.  8Carpismus;  brachiale;  raseta. 


THE  SKELETON. 


137 


FIG.  105. 


the  wrist,  are  the  scaphoid,  lunar,  cuneiform,  and  pisiform  bones ;  and 
those  of  the  second  row,  in  the  same  direction,  are  the  trapezial,  trape- 
zoid,  capitate,  and  unciform  bones. 

The  Scaphoid  bone1  is  the  largest  of 
the  first  row  of  the  carpus,  and  is  oblique 
in  its  position.  It  is  oblong,  concavo- 
convex,  with  a  tubercle  on  the  outer  end 
for  the  attachment  of  the  annular  liga- 
ment. It  articulates  with  the  radius 
above,  the  lunar  bone  within,  and  the 
trapezial,  trapezoid,  and  capitate  bones 
below. 

The  Lunar  bone2  is  the  second  in  size 
of  the  first  carpal  row,  and  is  square  and 
concavo-convex.  It  articulates  with  the 
radius  above,  the  scaphoid  bone  on  its 
outer,  and  the  cuneiform  bone  on  its  inner 
side,  and  the  capitate  and  unciform  bones 
below. 

The  Cu/neiforin  bone3  is  irregularly 
pyramidal,  and  articulates  with  the  lunar 
and  unciform  bones  on  its  outer  side,  and 
the  pisiform  bone  in  front. 

The  Pisiform  bone,4  irregularly  round- 
ed, is  the  smallest  of  the  first  carpal  row, 
and  articulates  alone  with  the  cuneiform 
bone. 

The  Trape'zial  bone5  is  the  third  in  size  of  the  second  carpal  row, 
and  is  irregular  in  form.  In  front  it  has  a  groove,  which  accommo- 
dates the  tendon  of  the  radio-carpal  flexor,  bounded  by  a  ridge  exter- 
nally, which  gives  attachment  to  the  annular  ligament.  It  articulates 
above  with  the  scaphoid  bone,  below  with  the  first  metacarpal  bone,  and 
on  the  inner  side  with  the  trapezoid  and  second  metacarpal  bones. 

The  Trap'ezoid  bone6  is  the  smallest  of  the  second  carpal  row,  and  is 


BONES  OF  THE  CARPUS,  and  those  with 
which  they  articulate ;  right  hand,  poste- 
rior view.  Of  the  npper  bones  U  is  the 
lower  end  of  the  ulna,  and  II  is  the  lower 
end  of  the  radius ;  F  indicates  the  posi- 
tion of  a  nbro-cartilage  which  separates 
the  radio-carpal  from  the  radio-ulnar  ar- 
ticulation. Of  the  bones  of  the  carpus,  in 
the  first  row,  S  is  the  scaphoid,  L  the  lu- 
nar; C  the  cuneiform,  and  P  the  pisiform 
bone ;  and  in  the  second  row,  T  T  are  the 
trapezial  and  trapezoid  bones,  7  the  capi- 
tate, and  U  the  unciform  bones.  Below, 
are  the  bases  of  the  metacarpal  bones. 


1  Os  scaphoideuin;  os  scaphoides;   os 
naviculare ;     os    cotyloides ;     os    cymbi- 
forme ;  boat-like  bone. 

2  Os  lunatum,  or  lunare  ;  os  semiluna- 
tum,  or  semilunare. 

3  Os  cuneiforme ;    os  triquetrum  ;    os 
pyramidale ;    os   cubitale ;    os   triangu- 
lare. 


4  Os  pisiforme ;   os  subrotundum ;  os 
orbiculare ;  os  lentiforme ;  os  extra  or- 
dinem  carpi. 

5  Trapezium;  os  trapezium,  or  trape- 
zoides;  os  multangulum  majus;  os  rhom- 
boides. 

6  Os  trapezoides ;  os  multangulum  mi- 
nus ;  os  trapezium ;  os  pyramidale. 


138  THE  SKELETON. 

an  irregular  truncated  pyramid,  wedged,  with  its  narrow  end  forward,  be- 
tween the  scaphoid  bone  above  and  the  second  metacarpal  bone  below, 
the  trapezial  bone  on  its  outer  side  and  the  capitate  bone  on  its  inner 
side. 

The  Cap'itate  bone,1  the  largest  of  the  second  carpal  row,  has  a  promi- 
nent convex  head  articulating  with  the  scaphoid,  lunar,  and  unciform 
bones,  and  an  irregular  cubical  base  joining  the  trapezoid  and  unciforrn 
bones  at  the  sides,  and  the  intermediate  three  metacarpal  bones  below. 

The  TJn/ciform  bone,2  the  second  in  size  of  the  second  carpal  row,  is 
irregularly  quadrate,  and  has  a  broad  hook-like  process  in  front  for  the 
attachment  of  the  annular  ligament.  It  articulates  above  with  the  lunar 
and  cuneiform  bones,  on  its  outer  side  with  the  capitate  bone,  and  below 
with  the  last  pair  of  metacarpal  bones. 

All  the  carpal  bones  are  composed  of  spongy  substance,  with  a  thin 
layer  of  compact  substance. 

Associated,  the  bones  of  the  carpus  form  a  convexity  on  the  dorsal 
surface,  and  a  concavity  toward  the  palmar  surface.  The  concavity  on 
the  inner  side  is  bounded  by  the  pisiform  bone  and  the  hook-like  process 
of  the  unciform  bone  ;  on  the  outer  side  by  the  tuberosity  of  the  scaphoid 
bone  and  the  ridge  of  the  trapezial  bone.  Between  the  two  sides  a 
strong  fibrous  band,  the  anterior  annular  ligament,  is  extended,  con- 
verting the  carpal  concavity  into  a  canal,  through  which  the  flexor  ten- 
dons reach  the  palm  of  the  hand. 

The  upper  border  of  the  carpus,  as  formed  by  the  scaphoid,  lunar,  and 
cuneiform  bones,  is  convex,  and  forms  the  lower  part  of  the  radio-ca-rpal 
articulation,  with  which  the  pisiform  bone  has  no  connection.  The 
lower  border  of  the  carpus  forms  an  irregular  transverse  plane,  with 
which  the  metacarpus  articulates.  The  capitate  and  unciform  bones 
together  form  a  convex  prominence  received  into  a  concavity  formed  by 
the  scaphoid,  lunar,  and  cuneiform  bones,  an  arrangement  of  the  two 
rows  of  carpal  bones  which  contributes  to  the  strength  of  their  articu- 
lation. 

BONES  OF  THE  METACAEPUS. 

The  Metacar'pal  bones,3  or  those  which  compose  the  metacarpus,4 
correspond  in  number  with  the  fingers,  which  they  join  below.  They 
belong  to  the  class  of  long  bones,  and  are  slightly  bent  forward. 
Their  shaft  is  trilateral,  convex  behind,  and  sloping  off  on  each  side 

1  Os  capitatum;  os  magnum.    In  some          3  Ossa  metacarpi. 

animals  the  smallest  bone  of  the  wrist.  4  Metacarpion  ;  postcarpium ;  postbra- 

2  Os  unciforme,  or  uncinatum;  os  ha-       chiale;  torsus  manus. 
matum ;  os  cuneiforme. 


THE  SKELETON. 


139 


FIG.  106. 


anteriorly.  Their  upper  extremity  or  base  is  quadrate,  and  varies  in 
character  with  the  difference  of  articulation  with  the  carpus.  Their 
lower  extremity  forms  a  spheroidal  head,1  with  a  pit  and  pair  of  tuber- 
cles on  each  side  for  ligamentous  attachment. 

The  metacarpal  bone  of  the 
thumb2  is  the  shortest  and  most 
robust.  It  is  also  disconnected 
and  divergent  from  the  others.  The 
succeeding  bones  gradually  dimin- 
ish in  size  to  the  last,  and  lie  nearly 
parallel  to  one  another.  They  are 
articulated  at  their  contiguous  ex- 
tremities, and  form  the  least  mov- 
able portion  of  the  hand. 

The  spaces  between  the  meta- 
carpal bones  are  called  inter- 
osseous,  are  numbered  from  with- 
out inward,  and  are  occupied  by 
muscles. 


BONES  OF  THE  FINGERS. 


THE  IEFT  HAND,  viewed  in  front,  or  on  the  palmar 
surface.  1,  scaphoid  bone ;  2,  semilunar ;  3,  cunei- 
form; -J,  pisiform;  5,  trapezial;  6,  groove  in  the 
latter;  7, trapezoid;  8,  capitate;  9,  unciform;  10, 
the  five  metacarpal  bones;  11,  first  row  of  pha- 
langes of  the  fingers;  12,  second  row;  13,  las.t 
row ;  14, 15,  phalanges  of  the  thumb. 


The  Fingers3  are  named,  in  suc- 
cession, the  thumb,4  the  index  or 
forefinger,5  the  middle  finger,6  the 
ring  finger,7  and  the  little  finger.8  Each  has  three  bones,  called  pha- 
lan'ges,9  or  joints,  except  the  thumb,  which  has  two.  The  middle 
finger  is  the  longest,  the  index  and  ring  fingers  are  next  in  length  and 
nearly  equal.  The  three  bones  of  the  little  finger  are  longer  than  the 
two  of  the  thumb,  but  these  are  much  more  robust,  and  the  last  phal'- 
anx  of  the  latter  is  larger  than  the  corresponding  bone  of  any  of  the 
other  fingers. 


1  Capitulum. 

2  Os  metacarpi  pollicis. 

3  Digiti,  dactyli. 

4  Pollex;  allus  pollex;  digit  us  primus, 
or  magnus :  promanus ;  anticheir ;  ma- 
ims parva  majori  adjutrix. 

5  Digitus   index,   secundus,   salutaris, 
or  demonstratorius ;   indicator ;  demon- 
strator ;  lichanos. 


6  Digitus  medius,  tevtius,  famosus,  in- 
famis,  impudicus,  obscoenus,  or  verpus  ; 
long  finger. 

7  Digitus  annularis,  quartos,  medicus, 
or  cordis ;  paramesos  ;  iatricus. 

8  Digitus   parvus,    minimus,    quintus, 
auricularis,  myops,  or  otites. 

9  Phalangial  bones ;  oesa,  nodi,  inter- 
nodia,  articuli,  condyli,  agmina,  acies, 
scutulee,  or  scytalides  digitorum  manus. 


140  THE  SKELETON. 

The  first  row  of  phalan'ges1  are  the  largest.  They  have  a  demi- 
cylindrical  shaft,  convex  behind  and  flattened  in  front,  with  a  ridge  on 
each  side  for  the  attachment  of  the  vaginal  ligaments.  The  upper 
extremity  or  base  is  the  most  expanded  portion  of  these  bones,  and 
supports  a  concave  articular  surface  for  the  head  of  the  metacarpal 
bones,  and  on  each  side  a  tubercle  for  the  attachment  of  lateral  liga- 
ments. The  inferior  extremity  presents  a  pulley-like  articular  surface, 
or  troch'lea,  for  the  second  phalanges,  and  a  slight  fossa  on  each  side 
for  lateral  ligaments. 

The  second  row  of  phalan'ges2  are  constructed  like  those  of  the  first 
row,  except  that  their  upper  extremity  supports  a  double  concavity,  to 
correspond  with  the  trochlea  of  the  former. 

The  third  row  of  phalanges3  are  the  shortest.  Their  base  is  con- 
structed like  that  of  the  second  row,  their  shaft  is  compressed  conical, 
and  they  end  in  a  rough  tuberosity  for  the  attachment  of  the  soft  tips  of 
the  fingers. 

In  front  of  the  head  of  the  metacarpal  bone  of  the  thumb  are  placed, 
side  by  side,  the  two  ses'amoid  bones.4  They  are  oval,  with  a  palmar 
convex  surface  enveloped  in  the  tendon  of  the  short  flexor  of  the  thumb, 
and  with  an  articular  facet  moving  upon  the  head  of  the  metacarpal 
bone. 

THE  HAND. 

The  Hand  at  rest  occupies  the  same  plane  as  the  forearm,  but  by 
means  of  the  mobility  of  the  radio-carpal  articulation  or  wrist  joint  it 
may  be  brought  nearly  to  a  right  angle  before  and  behind,  and  also  may 
be  moved  at  an  obtuse  angle  outward  and  inward. 

The  dorsal  surface  or  back  of  the  hand  is  convex.  When  the  hand 
is  closed  as  in  forming  the  fist,  the  heads  of  the  metacarpal  bones  and 
extremities  of  the  phalanges  become  prominent,  as  the  knuckles.  The 
inner  or  palmar  surface  is  concave,  and  is  rendered  more  so  by  the 
flexion  of  the  fingers.  The  concavity  of  the  metacarpus  is  the  basis  of 
the  palm5  or  hollow  of  the  hand. 

The  fingers  may  all  be  flexed  or  bent  inward  at  a  right  angle  to  the 
metacarpus,  but  cannot  be  extended  or  bent  backward  beyond  the  line 
of  the  latter.  They  are  all  capable  of  convergence  and  divergence,  or 
of  adduction  and  abduction.  The  phalanges  may  be  flexed  at  right 

1  Metacarpal  phalanges ;  procondyli.  *  Ossa  sesamoidea. 

2  Middle  phalanges ;  mesocondyli.  5  Palma;  vola;  platea;  thenar;  pocu- 
8  Phalanges  unguium  ;  metacondyli.          lum;  patera;  supellex  Diogenis. 


THE  SKELETON.  141 

angles  with  one  another,  and  extended  back  to  their  former  straight 
line,  but  have  no  other  movement. 

From  the  mobility  of  the  first  metacarpal  on  the  trapezial  bone,  the 
thumb  is  opposable  to  the  other  fingers,  and  enjoys  a  greater  range  of 
movement.  The  different  length  of  the  fingers  makes  their  tips  cor- 
respond with  the  hollow  of  the  hand  when  this  is  closed,  and  perhaps 
adapts  them  better  for  seizing  objects  of  varied  forms ;  and  thus  when 
a  spherical  body  is  clasped  it  will  be  found  that  the  tips  of  the  fingers 
are  brought  to  the  same  plane. 

DEVELOPMENT  OF  THE  BONES  OF  THE  UPPER  EXTREMITIES. 

The  clavicle  commences  to  ossify  earlier  than  any  other  bone.  It  is 
developed  from  a  principal  piece,  and  an  epiphysis  which  appears  at  the 
sternal  end  on  the  approach  of  adult  age. 

The  scapula  commences  ossification  about  the  same  time  as  the  vert- 
ebrae. It  is  formed  from  a  principal  piece,  and  several  epiphyses  added 
subsequent  to  birth.  The  acromion  and  coracoid  process  are  each 
formed  from  two  epiphyses,  another  is  developed  at  the  lower  angle, 
and  one  along  the  base  of  the  scapula. 

The  humerus  commences  to  ossify  after  the  clavicle,  and  before  the 
vertebrae.  At  birth  the  shaft  is  ossified,  but  the  extremities  are  car- 
tilaginous. The  head  and  tuberosities  are  formed  from  two  ossific  centres ; 
the  condyles  and  lower  articular  extremity  from  four  centres. 

The  radius  and  ulna  begin  to  ossify  shortly  after  the  humerus.  Their 
extremities  are  cartilaginous  at  birth,  and  an  epiphysis  is  formed  for 
each. 

The  carpus  is  cartilaginous  at  birth,  and  ossification  commences  with 
the  capitate  bone  during  the  first  year.  Each  bone  is  developed  from 
a  single  ossific  centre. 

At  birth  the  shaft  of  the  metacarpal  bones  and  phalanges  is  ossified. 
Subsequently  the  head  of  the  inner  four  metacarpal  bones  is  formed  as 
an  epiphysis ;  but  in  the  first  metacarpal  bone  and  the  phalanges,  it  is 
the  base  which  appears  as  an  epiphysis. 

ARTICULATIONS  AND  MOVEMENTS  OF  THE  UPPER 
EXTREMITY. 

THE  STERNO-CLAVICULAR  ARTICULATION. 

The  joint  formed  between  the  upper  angle  of  the  sternum  and  the  end 
of  the  clavicle  is  surrounded  by  a  cap'sular  lig'ament,  the  stronger  por- 


142  THE  SKELETON. 


tions  of  which  constitute   the   anterior  and  posterior  ster'no-clavic'- 
ular  lig'aments.     The  joint  is  divided  into  two  parts  by  a  biconcave 

inter-artic'ular     fi'bro-car'tilage, 

FIG.  107.  which  is  attached  by  its  margin  to 

the  capsular  ligament,  the  firskcos- 
tal  cartilage,  and  the  upper  border 
of  the  clavicle. 

The  sterno-clavicular  articulation 
is  further  strengthened  by  two  ac- 
cessory ligaments:  the  inter-clav- 
ic'ular  lig'ament,1  a  narrow  band 
connecting  both  clavicles  across 

STERNO-CLAVICULAR,  COSTO-CLAVICULAR,  AND  cos-  ,  -,  D  ,-. 

TO-STERNAL  ARTICULATES.    1,  capsular  ligament  the  UPP6r  Part  °f  the  Sternum  J    and 

of  the  sterno-clavicular  articulation ;  2,  inter-clav-  the   COS'tO-Clavic'lllar  ligament,2  a 

icular  ligament ;  3,  costoclavicular  ligament;  4,  ^  ^^     Connecting    the    first 

inter-articular  nbro-cartilage ;   5,  anterior    costo- 

stemai  ligaments.  costal  cartilage  with  the  under  part 

of  the  clavicle. 

Notwithstanding  the  strong  ligamentous  union  of  this  joint,  which  is 
the  only  one  between  the  trunk  and  the  upper  extremity,  it  possesses  a 
considerable  degree  of  mobility  in  every  direction.  In  this  motion  the 
entire  limb  participates,  while  the  sternum  is  passive. 


THE   SCAPULO-CLAVICULAR  ARTICULATION. 

The  joint  formed  between  the  acromion  and  clavicle  is  surrounded  by 
a  cap'sular  lig'ament,  the  stronger  portions  of  which  are  the  superior 
and  inferior  acro'mio-clavic'ular  lig'aments.  It  possesses  but  little 
mobility,  end  is  further  restricted  by  the  cor'aco-clavic'ular  ligament,3 
which  consists  of  two  strong  fibrous  bands  passing  between  the  base  of 
the  coracoid  process  and  the  under  surface  of  the  clavicle. 

In  the  movements  of  the  bones  of  the  shoulder  the  centre  of  motion 
is  the  sterno-clavicular  articulation.  The  clavicle  and  scapula  from  this 
point  move  upward  and  downward,  forward  and  backward.  In  the 
movements  of  the  scapula,  it  glides  upward  and  downward,  or  forward 
and  outward ;  or  it  rotates  on  its  axis,  as  in  the  shrugging  of  the  shoul- 
ders. 

1  L.  interclaviculare.  3  L-  coraco-claviculare  ;  1.  conoides  et 

2  L.  costo-claviculare  ;  1.  rhomboides.         trapezoides  ;    1.  scapulae  commune   con- 

oides et  trapezoides. 


THE  SKELETON. 


143 


FIG.  108. 


THE  SHOULDER  JOINT. 

The  Scapulo-humeral  articulation  or  shoulder  joint  is  surrounded  by 
a  thin,  loose  cap'sular  lig'ament,1  which  is  attached  above  to  the  margin 
of  the  glenoid  cavity,  and  below  to  the  neck  of  the  humerus.  Its 
upper  part  is  much  strengthened  by  a  broad  band,  the  cor'aco-hu'- 
meral  lig'ament,2  which  extends  between  the  coracoid  process  and  the 
greater  tuberosity  of  the  humerus. 

The  shoulder  joint  is  the  most  movable  one  of  the  body;  possessing  a 
wide  range  of  motion  in  every  di- 
rection. From  this  circumstance 
it  is  very  liable  to  dislocation,  not- 
withstanding its  many  means  of 
protection. 

The  head  of  the  humerus  has 
more  than  three  times  as  much  sur- 
face as  the  glenoid  cavity  upon 
which  it  moves.  To  deepen  the 
cavity,  a  prismoid,  fibre-cartil- 
aginous band,  the  gle'noid  lig'- 
ament,3 is  attached  around  its  mar- 
gin. The  upper  part  of  this  lig- 
ament gives  origin  to  the  tendon 
of  the  long  head  of  the  biceps 
flexor  muscle,  which  passes  through 
the  shoulder  joint  to  the  bicipital 
groove  of  the  humerus,  and  acts 
functionally  the  part  of  a  ligament. 
As  it  passes  through  the  joint  it  is 
separated  from  the  cavity  by  a 
reflection  of  the  synovial  membrane. 

A  strong,  triangular,  fibrous  band,  the  cor'aco-acromial  ligament,4  is 
attached  by  its  apex  to  the  acromion,  and  by  its  base  to  the  coracoid 
process.  The  two  processes  thus  associated  form  a  wide  arch  above  the 
shoulder  joint,  which  prevents  the  dislocation  of  the  humerus  in  this  direc- 
tion, unless  the  arch  is  broken.  The  deltoid  muscle  also  contributes  greatly 
to  the  strength  and  protection  of  the  upper  part  of  the  shoulder  joint. 

In  front  and  behind,  the  latter  is  closely  enveloped  by  the  tendons  of 
the  subscapular,  supra-  and  infra-spinous,  and  lesser  terete  muscles,  as 


SCAPULO-CLAVICULAR  AND  SCAPULO-HUMERAL  AR- 
TICULATIONS. 1,  acromio-clavicular  articulation, 
surrounded  with  its  capsular  ligament ;  2,  coraco- 
clavicular  ligament ;  3,  coraco-acromial  ligament; 
4,  coracoid  ligament ;  5,  capsular  ligament  of  the 
shoulder  joint;  t>,  coraco-humeral  liganrent;  7,  ten- 
don of  the  biceps  flexor  muscle. 


1  L.  capsulare  magnum. 

2  L.  ascititium  ;  accessory  ligament. 

3  L.  glenoides. 


*  L.  coraco-acromiale ;   1.  triangulare ; 
1.  scapulae  proprium  anterius. 


144 


THE  SKELETON. 


they  proceed  to  be  inserted  into  the  tuberosities  of  the  humerus.  Infe- 
riorly  the  joint  is  in  relation  with  the  long  head  of  the  triceps  extensor 
muscle.  If  the  muscles  surrounding  the  shoulder  joint  are  detached,  on 
account  of  the  looseness  of  the  capsular  ligament,  the  head  of  the  humerus 
falls  nearly  an  inch  below  its  usual  point  of  contact  with  the  glenoid  cavity. 
The  movements  of  the  shoulder  joint  are  forward,  backward,  outward, 
upward,  and  downward,  and  those  of  circumduction  and  rotation. 

THE  ELBOW  JOINT. 

The  Elbow  joint  is  formed  between  the  humerus  and  both  bones  of 
the  forearm,  is  lined  with  a  single  synovial  membrane,  and  is  inclosed  by 
a  capsular  ligament  strengthened  with  lateral  ligaments. 


FIG.  109. 


FIG.  110. 


THE  ELBOW  JOINT,  right  side,  viewed  antero-inter- 
nally.  1,  the  capsular  ligament  in  front ;  2,  inter- 
nal lateral  ligament;  3,  annular  ligament;  4, round 
ligament;  5,  interosseous  membrane;  6,  internal 
condyle. 


THE  SAME  ELBOW  JOINT,  viewed  externally.  1, 
posterior  surface  of  the  humerus ;  2,  ulna ;  3,  ra- 
dius; 4,  external  lateral  ligament;  5,  6,  annular 
ligament;  7,  8,  capsular  ligament;  9,  interosseous 
membrane. 


The  cap'sular  lig'ament,1  thin  and  loose,  is  attached  above  the  articu- 
lar surface  of  the  humerus,  including  the  pits  for  the  accommodation  of 
the  olecranon  and  coronoid  process ;  and  is  attached  below  to  the  margin 
of  the  sigmoid  cavities  of  the  ulna  and  to  the  annular  ligament.  Its 
back  portion  is  much  weaker  than  its  fore  part. 


Membrana  capsularis  cubiti. 


THE  SKELETON.  145 

The  internal  lateral  ligament1  is  a  strong  band  radiating  from  the 
internal  condyle  of  the  humerus  to  the  inner  margin  of  the  greater  sig- 
moid  cavity  of  the  ulna,  between  the  olecranon  and  coronoid  process.  The 
external  lateral  ligament2  is  a  narrow  band  extended  between  the  external 
condyle  and  the  annular  ligament  surrounding  the  head  of  the  radius. 

The  ordinary  movements  of  the  bones  of  the  forearm  upon  the  humerus 
are  those  of  flexion  and  extension.  The  motions  of  the  ulna  are  restricted 
to  these  alone,  but  the  radius  has  in  addition  a  rotary  movement  occur- 
ring upon  the  ulna  and  humerus  together. 

THE  SUPERIOR  RADIO-ULNAR  ARTICULATION. 

The  superior  radio-ulnar  articulation  forms  part  of  the  elbow  joint, 
one  synovial  membrane  and  capsular  ligament  being  common  to  both. 
The  head  of  the  radius  and  the  lesser  sigmoid  cavity  of  the  ulna  form 
this  articulation,  the  former  being  surrounded  by  a  strong  fibrous  band, 
the  an'nular  ligament,3  the  extremities  of  which  are  attached  to  the 
ulna  before  and  behind  the  latter  cavity. 

THE  MIDDLE  RADIO-ULNAR  ARTICULATION. 

The  lower  four-fifths  of  the  interval  of  the  radius  and  ulna  are  occu- 
pied by  the  interos'seous  membrane,4  which  is  thin  but  strong,  and  is 
composed  of  oblique  fibres  descending  from  the  sharp  edge  of  the  radius 
to  the  opposed  edge  of  the  ulna.  It  is  perforated  by  blood-vessels,  and 
serves  to  give  origin  to  some  of  the  muscles  of  the  forearm,  as  well  as 
to  connect  the  bones. 

At  the  upper  part  of  the  interosseous  space  an  oblique  band,  the  round 
ligament,5  descends  from  the  coronoid  process  of  the  ulna  to  the  radius 
below  its  tuberosity. 

THE  INFERIOR  RADIO-ULNAR  ARTICULATION. 

The  inferior  radio-ulnar  articulation  is  separated  from  the  wrist  joint 
by  a  triangular,  interarticular  fibro-cartilage,  the  base  of  which  is  attached 
to  the  lower  margin  of  the  semilunar  cavity  of  the  radius,  and  the  apex 
to  the  pit  between  the  styloid  process  and  head  of  the  ulna.  This  ar- 
ticulation is  surrounded  by  a  loose  capsular  ligament6  connected  witji 
the  articular  margins  of  the  radius,  ulna,  and  fibro-cartilage. 

1  L.  laterale  internum;   1.  brachio-cu-          4  L.  interosseum;membranainterossea. 
bitale;  1.  radiatum ;  1.  triangulare.  5  L.  teres;  1.  obliquum;  chorda  trans-  ' 

2  L.  laterale  externum  ;  1.  brachio-ra-      versalis. 

6  Membrana  capsularis  sacciformis. 

3  L.  annulare ;  1.  orbiculare. 

10 


146 


THE   SKELETON. 


The  radius  rotates  inwardly  upon  the  ulna  and  becomes  obliquely 
crossed  in  front  of  it.  The  hand  follows  the  motion  of  the  radius,  in 
the  pendant  condition  of  the  upper  extremity  the  palm  becoming  directed 
backward ;  and  this  constitutes  the  movement  of  pronation.  The  reverse 
motion,  by  which  the  radius  assumes  a  position  parallel  to  the  outer  side 
of  the  ulna,  and  the  palm  of  the  hand  is  directed  forward,  is  called  that 
of  supination. 

In  these  movements  of  the  radius,  its  head  rotates  upon  the  humerus 
and  the  lesser  sigmoid  cavity  of  the  ulna  within  the  annular  ligament, 
and  its  lower  extremity  rotates  upon  the  head  of  the  ulna. 


FlG    111 


THE  WRIST  JOINT,  OR  RADIO-CARPAL  ARTICULATION. 

The  Wrist  joint  is  formed  above  by  the  radius  and  triangular  fibro- 

cartilage    connecting     it 

LIGAMENTS  OF  THE  WRIST  AND  .  .,      , 

HAND,  anterior  view.    1,  lower  With  the  Ulna  J   and  belOW 

part  of  the  interosseous  mem-  by    the     Scaphoid,     lunar, 

brane;  2,  lower  radio-ulnar  ar-  j              -f>            •> 

ticulation  inclosed  byacapsu-  &nd  CUneitorm   bonCS.      It 

lar  ligament;  3,  fore  part  of  the  ig      inclosed      by    a     loOSC 

radio-carpal  joint  inclosed  by  .      ,        , .     . 

a  capsular  ligament;  4,  exter-  CaP  SUlar  ilS  ament   COn- 

nal    lateral    ligament  of   the  nCCted    with   the   COntigU- 

wrist;  5  internal  lateral  liga-  margins    Qf    the     ar. 
ment;    6,   palmar   portion  of 

the  capsular  ligament  of  the  ticulai*     SUrfaCCS.          It     is 
carpus;  7,  pisiform  bone  with  strengthened  by  a  strong 
its  capsular  ligament ;  8,  pal- 
mar portion  of  the  capsular  rounded,  internal  lateral 

ligament  connecting  the  car-  Jjp-QTYie 
pus  with  the  base  of  the  meta- 
carpus; 9,  capsular  ligament  StylOlu 
of  the  trapezial  arid  metacar-  ^[^, 
pal  bone  of  the  thumb ;  10,  pal- 

mar  or  anterior  ligament  of  bone  ;    and    a    Strong    CX- 

the  metacarpo-phalangial  ar-  temal  lateral  ligament,3 
ticulation  of  the  thumb;  11, 

external  lateral    ligament  of  extended  between  the  Sty- 

the  same  joint;  12,  palmar  or  10J(J  proCCSS  of  the  1'adlUS 

anterior  ligament  of  the  cor-  ,     ,                 ,      .  ,  , 

responding  joint  of  the  index  &nd  the  SCapllOld  bone, 

finger, represented  as  removed  A  Single  SynOVial  mem- 

in  the  other  fingers;  13, lateral  ligaments  of  the  same  articulation;  ^rane  ]jne§  tjie  ra(Ji0.car. 

14,  transverse  ligaments  connecting  the  heads  of  the  contiguous 

metacarpal  bones;  15, 16,  palmar  or  anterior  ligaments  and  lateral  pal  articulation,  and    nei- 

ligaments  of  the  phalangial  articulations.  tjier     COmmUllicateS     With 

the  radio-ulnar  articulation  nor  extends  between  that  of  the  carpal  bones. 

1  Anterior  and  posterior  radio-carpal  2  L.  laterale  internum;  1.  laterale  ul- 

ligaments ;  1.  accessorium  rectum  et  ob-  nare  ;  funiculus  ligaraentosus. 

liquum  et  rhomboideum  ;  membrana  ar-  3  L.  laterale  externum ;  1.  laterale  ra- 

ticuli  cubiti  et  carpi  capsularis.  diale. 


,2  Connecting  tllC 

& 

prOCCSS      of      the 
Q    cuneiform 


THE  SKELETON.  147 

The  movements  of  the  wrist  joint  are  flexion  and  extension,  abduc- 
tion and  adduction,  and  circurnduction.  The  turning  of  the  hand  de- 
pends on  the  rotation  of  the  radius. 

THE  INTERCARPAL  AND  CARPO-METACARPAL  ARTICU- 
LATIONS. 

The  pisiform  bone  forms  a  distinct  joint  with  the  cuneiform  bone,  sur- 
rounded by  a  strong  capsular  ligament  lined  with  synovial  membrane. 

The  scaphoid,  lunar,  and  cuneiform  bones  of  the  first  row  of  the  carpus 
are  connected  at  their  upper  part  by  intervening  interos'seous  liga- 
ments. In  the  same  manner  the  trapezoid,  capitate,  and  unciform  bones 
of  the  second  row  are  connected  at  their  middle,  and  this  is  likewise  the 
case  with  the  bases  of  the  inner  four  metacarpal  bones. 

All  the  carpal  bones  except  the  pisiform  bone,  and  the  bases  of  all 
the  metacarpals,  except  that  of  the  thumb,  are  connected  with  one 
another  by  short  fibrous  bands  constituting  the  pal'mar  and  dor'sal 
ligaments.  The  association  of  these  ligaments  forms  a  sort  of  capsular 
ligament  investing  the  carpus  and  base  of  the  metacarpus. 

A  single  synovial  membrane  lines  the  intercarpal  and  carpo-metacarpal 
articulations.  These  joints  possess  but  little  mobility,  except  the  one 
between  the  two  rows  of  carpal  bones,  which  has  a  hinge-like  motion. 

The  metacarpal  bone  of  the  thumb  forms,  with  the  trapezial  bone,  a 
freely  movable  joint  surrounded  with  a  capsular  ligament.  Each  articu- 
lating surface  is  convex  in  one  direction  and  concave  in  the  other,  and 
the  two  surfaces  are  applied  in  a  crossing  manner,  allowing  the  meta- 
carpal bone  to  be  moved  backward  or  forward,  inward  or  outward,  thus 
rendering  the  thumb  opposable  to  the  other  fingers. 

The  heads  of  the  inner  four  metacarpal  bones  are  associated  in  front 
by  thin  and  rather  loose  transverse  ligaments, 

THE  METACARPO-PHALANGIAL,  AND  PHALANGIAL  ARTICU- 
LATIONS. 

The  metacarpo-phalangial,  and  phalangial  articulations,  are  con- 
nected by  strong  lateral  ligaments,  which  descend  from  the  sides  of  the 
bones  above,  obliquely  forward  to  the  sides  of  the  bones  below.  The 
fore  part  of  these  articulations  is  protected  by  a  thick,  fibro-cartilaginous 
palmar  ligament,1  extended  between  the  position  of  the  lateral  liga- 
ments. It  is  firmly  attached  to  the  margin  of  the  bone  below  the  joint, 
and  but  slightly  to  that  above ;  and  it  is  grooved  on  its  palmar  aspect 

1  Anterior  ligament. 


148  THE   SKELETON. 

for  the  passage  of  the  flexor  tendons.  The  back  part  of  these  articula- 
tions is  covered  by  the  expanded  extensor  tendons,  which  act  in  this  po- 
sition as  ligaments. 

The  spheroidal  head  of  the  metacarpal  bones,  and  the  single  concavity 
of  the  bases  of  the  first  row  of  phalanges,  permit  the  movements  of 
flexion  and  extension,  abduction  and  adduction. 

The  phalangial  articulations  or  finger  joints  possess  only  the  move- 
ments of  flexion  and  extension. 


THE   LOWER  EXTREMITY. 

The  lower  extremity  extends  from  below  the  pelvis,  with  which  it 
articulates  by  means  of  the  head  of  the  thigh  bone.  Each  consists  of  a 
single  bone  to  the  thigh,  one  to  the  knee,  two  to  the  leg,  and  twenty- 
eight  to  the  foot. 

THE  FEMUR. 

The  Fe'nmr,  or  thigh  bone,1  is  the  largest  and  longest  bone  of  the 
skeleton,  and  extends  from  the  hip  bone  downward,  with  an  inward 
inclination,  to  the  tibia. 

The  shaft  is  cylindrical,  with  a  prominent  crest  behind,  called  the  as'per- 
ous  ridge,  (linea  aspera.)  Its  front  and  sides  are  smooth,  and  occupied  by 
the  quadriceps  extensor  muscle.  The  asperous  ridge,  for  the  attachment 
of  muscles,  is  acute  at  the  middle,  and  is  rough  only  at  its  upper  part, 
which  diverges  in  two  divisions  to  the  trochanters.  Its  lower  part  is 
less  well  developed,  and  diverges  in  two  divisions  to  the  condyles,  in- 
closing a  triangular  surface  forming  the  basis  of  the  popliteal  space. 

The  upper  extremity  of  the  shaft  terminates  in  two  processes,  called 
trochan'ters,2  The  greater  trochan'ter  is  situated  at  the  highest  part 
of  the  shaft  externally.  It  is  convex  and  rugged  on  its  outer  surface, 
and  presents  an  oblique  ridge  for  the  attachment  of  the  middle  gluteal 
muscle.  Its  inner  surface,  less  extensive,  exhibits  a  pit,  the  trochanter'ic 
fos'sa,3  into  which  the  small  rotary  muscles  of  the  thigh  are  inserted. 
The  smaller  trochan'ter4  is  a  rounded  eminence  situated  at  the  posterior 
and  inner  side  of  the  bone,  and  gives  attachment  to  the  tendon  of  the 
psoas  and  iliac  muscles. 

In  front  and  behind,  the  trochanters  are  conjoined  by  the  intertro- 
chanter'ic  ridges,  of  which  the  posterior  is  much  the  most  prominent, 

1  Os  femoris  ;  meriura.'  3  Fossa  trochanterica. 

2  Trochanteres;  rotatores.  *  Lineae  trochantericse. 


THE  SKELETON. 


149 


FIG.  112. 


and  gives  attachment  to  the  quadrate  femoral  muscle.     The  anterior 
ridge  is  feebly  developed,  but  is  longer  than 
the  other. 

From  the  trochanters  and  their  associating 
ridges  the  neck  of  the  femur1  projects  upward 
and  inward  at  an  obtuse  angle  from  the  shaft. 
It  is  cylindrical,  compressed  from  before  back- 
ward, and  joins  the  latter  by  a  strong,  expanded 
base.  It  supports  a  spherical  head,2  which  is 
covered  with  cartilage,  and  articulates  with  the 
acetabulum.  On  the  inner  side  of  the  head  is 
a  pit  for  the  attachment  of  the  round  ligament 
of  the  hip  joint. 

The  lower  extremity  of  the  femur  is  the 
most  expanded  and  massive  portion  of  the 
bone.  It  terminates  in  two  large  eminences, 
the  con'dyles,  which  are  separated  behind  by  a 
deep  notch,  the  intercon'dyloid  fos'sa.3  The 
articular  surfaces  of  the  condyles  are  continu- 
ous in  front  by  a  pulley-like  surface,  the 
troch'lea,  upon  which  the  knee-cap  moves. 
The  internal  con'dyle  is  the  larger,  but  the 
external  con'dyle  projects  most  anteriorly.  On 
the  remote  sides  of  the  condyles  is  a  tuberos'- 
ity4  for  the  attachment  of  the  lateral  ligaments 
of  the  knee  joint.  Below  the  external  tuberos- 
ity is  a  crescentic  fossa,  which  gives  origin  to 
the  tendon  of  the  popliteal  muscle. 

When  the  femur  is  placed  vertically,  the  in- 
ternal condyle  appears  much  longer  than  the 
external,  and  the  summit  of  the  greater  tro- 
chanter  rises  nearly  as  high  as  the  head  of  the 
bone.  The  natural  position  of  the  latter  is 
oblique,  so  that  the  lower  extremities  of  both  thigh  bones  are  brought 
nearly  into  contact,  and  the  upper  extremities  are  the  most  remote  from 
each  other.  In  this  position  the  articulating  surfaces  of  the  condyles 
are  on  a  level,  and  the  summit  of  the  greater  trochanter  is  on  the  same 
line  with  the  centre  of  the  head. 

In  the  female  the  neck  of  the  femur  is  longer  and  more  rectangular 


FEMUR  OF  THE  RIGHT  SIDE,  front 
view.  1,  the  shaft;  2,  head;  3, 
neck;  4,  great  trochanter;  5,  ante- 
rior inter-trochanteric  ridge;  6,  less- 
er trochanter;  7,  external,  and  8, 
internal  condyles;  9,  tuberosity 
for  the  external  lateral  ligament; 

10,  groove  for  the  popliteal  tendon; 

11,  tuberosity  for  the  internal  lat- 
eral ligament. 


1  Cervix,  or  collura  fernoris. 

2  Caput  femoris. 


3  Fossa  intercondyloidea  ;  f.  poplitea. 

4  Tuberositas  condyli. 


150  THE  SKELETON. 

in  its  relation  with  the  shaft  than  in  the  male,  so  that  the  thigh  bones  in 
the  former  sex  are  more  oblique  or  more  divergent  above. 

One  or  two  canals,  for  the  principal  medullary  nutritious  vessels, 
ascend  at  the  inner  side  of  the  asperous  ridge,  in  the  vicinity  of  its 
middle. 

THE  PATELLA. 

The  Patel'la,  or  knee-cap,1  viewed  by  some  anatomists  as  the  repre- 
sentative of  the  olecranon,  by  others  as  a  sesa- 
moid  bone  of  the  tendon  of  the  quadriceps  ex- 
tensor muscle,  is  situated  in  front  of  the  knee 
joint.  It  is  a  chestnut-shaped  bone,  with  its 
apex  downward  and  attached  by  a  strong  lig- 
ament to  the  tibia.  Its  base  is  thick,  and  has 
inserted  into  it  the  tendon  of  the  quadriceps 
extensor.  Its  fore  part  is  convex  and  rough  ; 
PATELLA  OF  THE  RIGHT  SIDE,  pos-  and  its  back  part  presents  a  transversely  oval 

terior  view.     1,  2,  articular  faces      articular    surface,  elevated    from  each    Side  into 
for  the  trocnlea  of  the  femur;  3, 

apex  of  the  bone  roughened  for  the    a  median  ridge  so  as  to  correspond  with  the 
attachment  of  its  ligament.  trochlea  of  the  femur,  upon  which  it  moves. 

The  patella  is  composed  of  a  mass  of  spongy  substance  enveloped 
in  a  thin  layer  of  compact  substance. 

THE  BONES  OF  THE  LEG. 

The  bones  of  the  leg  consist  of  the  tibia  and  fibula,  placed  side  by 
side.  The  tibia  joins  the  femur  above,  and,  together  with  the  fibula,  joins 
the  astragalus  below.  The  former  alone  receives  the  pressure  of  the 
upper  part  of  the  body,  and  transmits  it  to  the  foot ;  while  the  latter 
appears  mainly  of  importance  in  extending  the  surface  of  the  leg  for 
muscular  attachment. 

THE  TIBIA. 

The  TiVia,  or  shin  bone,2  situated  at  the  fore  and  inner  part  of  the  leg* 
extends  in  a  straight  line  from  the  thigh  bone  to  the  tarsus,  and  is  the 
second  largest  and  longest  bone  of  the  skeleton.  Its  shaft  is  a  trilateral 
prismatic  column,  with  sharp  borders,  and  is  most  expanded  toward  the 
upper  extremity.  The  inner  surface,  smooth  and  slightly  rounded,  is 

1Rotula;  epigonis ;  caucaloides;  su-  thyroides,  or  sesamoideum  magnum; 
pergenualis;  acromyle:  mylacris;  myle;  olecranon  mobile. 

mola;    gamba;    concha;    oculus;  orbis,  2  Cneme ;  procnemium  ;  focile  majus; 

orscutumgenu;  088cutiforme,disciforme,       arundo,  or  canna  major;  canna  domes- 

tica  cruris. 


THE   SKELETON. 


151 


FIG.  114. 


subcutaneous.  The  outer  surface,  occupied  by  muscles,  is  slightly 
grooved  above,  and  is  rounded  below,  where  it  inclines  forward.  The 
posterior  surface  is  flat  and  covered  with  muscles,  and  at  the  upper  part 
is  marked  by  a  feeble,  oblique  ridge,  indicating  the  lower  border  of 
attachment  of  the  popliteal  muscle.  The  anterior  border,  called  the 
crest  or  shin,1  is  waving  in  its  course,  and  acute  at  the  middle.  The 
outer  border  gives  attachment  to  the  interosseous  membrane ;  the  pos- 
terior border,  less  sharp  than  the  others,  gives  attachment  to  muscles. 

The  superior  extremity  expands  into  the  head,  which  is  the  most 
massive  portion  of  the  bone,  and  appears  as  if 
it  were  pressed  backward,  so  that  its  front  is 
flattened  and  it  overhangs  the  posterior  sur- 
face of  the  shaft.  Its  prominent  lateral  por- 
tions constitute  the  con'dyles,2  which  have  thick 
porous  borders,  and  support  a  pair  of  smooth, 
oval  surfaces,3  invested  with  cartilage,  for 
articulation  with  the  condyles  of  the  femur. 
The  inner  articular  surface  is  the  longer  antero- 
posteriorly,  and  is  slightly  concave  in  this 
direction  ;  while  the  other  is  slightly  convex. 
Both  are  elevated  at  the  middle  of  their  ap- 
proximate border  upon  a  small  pyramidal  emi- 
nence, the  spi'nous  proc'ess,4  the  base  of  which 
is  the  centre  of  attachment  for  the  semilunar 
cartilages  and  crucial  ligaments.  The  articular 
surfaces  are  separated  by  a  rough,  depressed 
tract,  which  crosses  the  spinous  process  and 
expands  on  the  fore  and  back  part  of  the  head. 
Below  the  back  part  of  the  external  condyle  is 
a  small,  smooth  surface,  covered  with  cartilage, 
for  articulation  with  the  head  of  the  fibula. 

Below  the  head,  in  front,  at  the  commence- 
ment of  the  crest,  is  a  conspicuous  eminence, 
the  tuberos'ity,5  into  which  the  ligament  of  the 
patella  is  inserted. 

The  lower  extremity  of  the  tibia  is  ex- 
panded, and  at  its  termination  is  quadrate.  In 
front  it  is  smooth  and  convex,  and  bounded  below  by  a  prominent  mar- 


TIBIA    AND    FIBULA    OF    THE    LEFT 

LEG.  1,  shaft  of  the  tibia;  2,  3,  con- 
dyles; 4,  spinous  process;  5,  tuber- 
osity ;  6,  crest  or  shin ;  7,  lower  ex- 
tremity of  the  bone ;  8,  internal 
mallcolus;  9,  shaft  of  the  fibula: 
10,  its  head ;  11,  external  mallef >- 
lua. 


1  Crista ;  spina. 

2  Condyli ;  tuberosities. 

3  Condyli. 


4  Acclivitas,  or  erninentia  condyloidea. 
or  intercondyloidea;  spine. 

5  Tuberositas  tibiae  ;  tuberculum  ;  tu- 
bercle. 


152 


THE   SKELETON. 


gin  for  the  attachment  of  the  capsular  ligament  of  the  ankle  joint. 
Behind,  it  slopes  to  an  obtuse  border,  for  the  same  purpose  as  the  latter, 
and  its  outer  side  is  excavated  and  roughened  for  liganientous  attach- 
ment with  the  fibula.  Its  inner  part  is  prolonged  into  a  strong  promi- 
nence, the  internal  malle'olus  or  ankle.1  The  inner  surface  of  this 
process  is  convex  and  subcutaneous ;  and  behind,  is  marked  with  a  groove 
for  the  tendon  of  the  posterior  tibial  muscle. 

At  the  bottom  of  the  tibia  is  the  tar 'sal  articular  surface,  a  quadri- 
lateral concavity,  which  at  its  inner  side  is  prolonged  downward  on  the 
malleolus.  It  is  covered  with  cartilage,  and  joins  the  upper  and  inner 
side  of  the  astragalus. 

The  canal  of  the  medullary  nutritious  vessels  is  situated  at  the  upper 
third  of  the  posterior  surface  of  the  shaft,  and  is  directed  downward. 


FIG.  115. 


THE  FIBULA. 

The  Fib'ula2  is  a  long,  slender  bone,  situated  at  the  outer  side  of  the 
tibia.  Its  upper  extremity  articulates  beneath  the  back 
part  of  the  head  of  the  latter ;  but,  in  descending,  the 
bone  gradually  advances  in  position,  so  that  its  lower 
extremity  is  nearly  as  far  forward  as  the  internal  mal- 
leolus, and  extends  rather  lower  than  this. 

The  shaft  presents  three  irregular  surfaces  separated 
by  prominent  borders.      The  inner  surface  is  divided 
by  an  oblique  ridge,  to  which  the  interosseous  membrane 
is  attached.     The  outer  surface  is  grooved  above  the 
middle ;  at  its  upper  part  inclines  forward,  and  at  its 
lower  part  inclines  backward. 
The  posterior  surface  is  con- 
vex ;  its  upper  part  inclining 
outward,  its  lower  part  in- 
ward. 

The  upper  extremity  ex- 
pands into  the  head,3  which 
is  prominent  at  the  sides  for 
the  attachment  of  ligaments 
and  the  tendon  of  the  biceps 
flexor ;  and  supports  at  its 
inner  part  a  small  smooth 
surface  for  articulation  with  the  external  condyle  of  the  tibia. 


TlBIA    AND  FIBULA   OF   THE  RIGHT 

LEG,  posterior  view.  1,  2,  articu- 
lar surfaces  for  the  condyles  of  the 
femur  separated  by  the  spinous  pro- 
cess; 3,  the  inner  condyle  of  the 
tibia;  4,  surface  occupied  by  the 
popliteal  muscle  defined  by  the  ob- 
lique line  5;  6,  nutritious  foramen ; 
7,  surface  covered  by  the  flexors  of 
the  toes;  8,  internal  malleolus;  9, 
grooves  for  tendons ;  10.  shaft  of  the 
fibula;  11,  its  head;  12,  subcuta- 
neous surface  at  the  lower  part  of 
the  bone;  13,  external  malleolus; 
14,  groove  for  tendons, 


1  Inner  ankle  bone. 

2  Os   perone ;    peroneum ;    canna,    or 
arundo  minor ;  sura ;  fistula  cruris ;  cru- 


ris  radius  ;  focile  minus  ;  tibia  minima  ; 
spell,  or  splinter  bone. 
3  Capitulum. 


THE   SKELETON.  153 

The  lower  extremity,  rather  larger  than  the  other,  is  prolonged,  below 
its  junction  with  the  tibia,  into  the  external  malle'olus  or  ankle.1  This 
is  longer  and  more  prominent  than  the  internal  one,  and  supports  a 
smooth,  triangular,  articular  facet,  which  joins  the  outer  side  of  the 
astragalus  and  forms  part  of  the  ankle  joint.  Behind  the  articular  sur- 
face is  a  fossa  for  the  attachment  of  the  external  lateral  ligament  of  the 
ankle  joint,  and  above  it  is  a  convexity,  which  is  conjoined  with  the  tibia 
by  means  of  a  ligament.  The  fore  part  of  the  malleolus  is  convex  and 
subcutaneous ;  and  its  back  part  is  marked  by  a  groove  for  the  tendons 
of  the  peroneal  muscles. 

The  canal  for  the  medullary  nutritious  vessels  is  situated  near  the 
middle  of  the  posterior  surface  of  the  shaft,  and,  like  that  of  the  tibia,  is 
directed  downward. 

BONES  OF  THE  FOOT. 

The  bones  of  the  foot  are  situated  at  a  right  angle  with  those  of  the 
leg,  and  are  subdivided  into  those  of  the  tarsus,  of  which  there  are    \ 
seven ;  those  of  the  metatarsus,  of  which  there  are  five ;  and  those  of    ) 
the  toes,  of  which  there  are  sixteen. 

BONES  OF  THE  TARSUS. 

The  Tarsal  bones,2  or  those  composing  the  tarsus,  seven  in  number, 
consist  of  the  astragalus  and  calcaneum,  the  scaphoid,  cuboid,  and  three 
cuneiform  bones. 

The  Astragalus,3  or  ankle  bone,  is  the  only  one  of  the  tarsus  which 
articulates  with  those  of  the  leg ;  and  is  the  highest  and  second  in  size 
of  the  former.  Its  posterior  part,  or  body,  is  quadrate,  and  is  received 
between  the  two  malleoli.  Its  upper  articular  surface,  for  the  tibia,  is 
antero-posteriorly  convex,  transversely  slightly  concave,  and  is  continu- 
ous at  the  sides  with  vertical  articular  surfaces  for  the  malleoli.  Be- 
neath the  body,  at  its  back  and  outer  part,  is  a  concave  articular  sur- 
face, which  rests  on  the  calcaneum.  In  advance  of  the  body  is  the  neck 
terminating  in  the  head,  which  supports  an  anterior,  convex,  articular 
surface  for  the  scaphoid  bone,  and  an  inferior  articular  surface  for  the 
calcaneum.  The  latter  surface  and  that  beneath  the  body  are  separated 
by  a  deep  groove,  corresponding  with  a  similar  one  of  the  calcaneum, 
for  an  interosseous  ligament. 

1  Outer  ankle  bone.  3  Talus  ;  quatrio  ;  diabebos ;  cavicula  ; 

2  Ossa  tarsi;  planta  prinia ;  rascetape-       cavilla;   tetroros  ;  astrion ;   os  balistse  ; 
dis ;  pedium ;  caviculse  pedis  nodus.  os  tesserae  ;  sling  bone ;  huckle  bone. 


154 


THE   SKELETON. 


FIG.  116. 


The  Calcan'eum,  or  heel  bone,1  is  the  largest  one  of  the  tarsus.  It  is 
placed  beneath  the  astragalus,  extends  nearly 
as  far  forward,  and  posteriorly  extends  far 
beyond,  where  it  forms  the  basis  of  the  heel. 
It  is  irregularly  oblong  quadrate.  At  its 
upper  part  in  front  is  a  large,  irregular  fossa, 
containing  two  articular  surfaces,  for  the  as- 
tragalus, separated  by  a  rough  tract.2  The 
larger  articular  surface  is  convex,  and  situated 
at  the  back  of  the  fossa ;  the  other  is  narrow 
and  concave,  and  rests  on  a  lateral  process3 
internally.  In  advance  of  the  fossa  is  a  ver- 
tical articular  surface  for  junction  with  the 
cuboid  bone.  Posteriorly,  the  calcaneum 
terminates  in  a  large,  convex  tuberosity,4  the 
lower  part  of  which  gives  attachment  to  the 
"tendon  of  Achilles."  The  upper  surface 
of  the  tuberosity  is  saddle  like,  and  cor- 
responds with  the  depression  above  each  side 
of  the  heel.  The  bottom  of  the  tuberosity 


bone;  5,  6,  7,  internal,  middle,  and 
external  cuneiform  bones ;  8,  cuboid 
bone;  9,  metatarsal  bones;  10,  11, 
phalanges  of  the  great  toe;  12,  13, 
14,  phalanges  of  the  other  toes. 


head;  3,  calcaneum;  4,  scaphoid  attachment  to  the  plantar  fascia  and  mus- 
cles. In  advance  of  the  tubercles,  the  under 
surface  of  the  bone  forms  an  obtuse  ridge. 
The  outer  surface  of  the  calcaneum  is  vertical 
and  rough.  Its  inner  surface  forms,  with  the 
lateral  process,  a  concavity,6  which  transmits  the  tendons  of  the  flexor 
muscles  and  the  plantar  vessels  and  nerves. 

The  Scaph'oid  bone,7  situated  at  the  inner  side  of  the  tarsus,  is  ovoid 
in  outline,  with  a  posterior  concave  articular  surface  for  the  head  of  the 
astragalus,  and  an  anterior  convex  surface,  divided  into  three  facets,  for 
junction  with  the  cuneiform  bones.  Its  upper  and  lower  borders  are 
rough ;  and  its  inner  part  forms  a  tuberosity  for  the  insertion  of  the 
posterior  tibial  muscle. 

The  Cu/boid  bone8  is  situated  at  the  anterior  outer  part  of  the  tarsus, 


1  Os  calcis ;  calcaneus  ;  calcar  pedis ; 
calcia ;  ichnis ;  pternium. 

2  Sulcus  calcanei. 

3  Processus  lateralis  ;    sustentaculum 
tali ;  small  apophysis. 

4  Tuberositas  calcanei ;    talus  ;    calx  ; 
heel. 

5  Greater  and  lesser  tuberosity. 


6  Sinuosity. 

7  Os  scaphoides ;  os  scaphoideum  ;  os 
naviculare ;    os   cymbiforme ;    boat-like 
bone. 

8  Os  cuboides ;   os  cubiforme  ;   os  cu- 
boideum;  os  cyboides ;  oscyrtoides;  os 
grandinosum  ;  os  tesserae  ;  os  varium. 


THE   SKELETON. 


155 


FIG.  117. 


and  is  the  third  in  size  of  the  tarsal  bones.  Its  upper  surface  inclines 
outwardly,  and  is  rough.  Its  under  surface,  also  rough,  presents  a  tu- 
berosity  for  the  attachment  of  the  calcaneo-cuboid  ligament,  and,  in 
advance  of  this,  a  groove  for  the  transmission  of  the  tendon  of  the  long 
peroneal  muscle.  Posteriorly  it  has  a  vertical  articular  facet  for  the 
calcaneum;  and  anteriorly,  another,  which  is  subdivided  to  join  the 
outer  two  metatarsal  bones.  Its  inner  surface  is  rough,  and  near  the 
middle  has  a  small  articular  facet  for  the  internal  cuneiform  bone. 

The  three  Cuneiform  bones1  are  situated  in  a  row  in  front  of  the  sca- 
phoid bone,  with  which  they  articulate. 
As  expressed  by  the  name,  they  are 
wedge  shaped.  The  internal  cuneiform 
bone2  is  the  largest,  and  has  its  base 
downward;  the  middle  cuneiform  bone3 
is  the  smallest,  and  it,  with  the  external 
cuneiform  bone,4  have  their  base  upward. 
The  three  bones  together  contribute  to 
the  dorsal  convexity  of  the  tarsus,  and  to 
its  plantar  concavity.  Anteriorly  they 
articulate  with  the  inner  three  metatarsal 
bones,  and  the  external  one  also  articu- 
lates with  the  cuboid  bone. 

All  the  tarsal  bones  are  composed  of 
masses  of  spongy  substance  with  a  com- 
paratively thin  investment  of  compact 
substance,  which  presents  many  perfora- 
tions for  the  transmission  of  vessels. 

The  tarsus  forms  one-half  of  the  length 
of  the  foot,  and  is  connected  near 
its  middle  with  the  leg.  Behind  the 
bones  of  the  latter,  a  small  portion  of 
the  astragalus  and  about  one-half  the 
length  of  the  calcaneum  project,  and  in 
front  of  them  project  the  head  of  the 
astragalus,  a  small  portion  of  the  calca- 
neum, and  the  five  smaller  tarsal  bones. 

The  portion  of  the  tarsus  in  front  of  the  ankle  joint,  or  the  instep,5  is 
convex  on  its  dorsal  surface  and  concave  on  its  plantar  surface.  On  the 


SOLE  OF  THE  LEFT  FOOT.  1,  concavity  of 
the  calcaneum ;  2,  outer  face  of  the  same ; 
3,  groove  for  the  tendon  of  the  long 
flexor  of  the  toes ;  4,  head  of  the  astragalus; 
5,  scaphoid  bone;  6,  its  tuberosity ;  7,8,9, 
internal,  middle,  and  external  cuneiform 
bones ;  10,  cuboid  bone ;  11,  its  groove  for 
the  tendon  of  the  long  peroneal  muscle ; 
12,  metatarsal  bones ;  13,  first  row  of  pha- 
langes; 14,  second  row;  15,  last  row;  16, 
last  phalanx  of  the  great  toe. 


1  Ossa  cuneiformia ;  ossa,  or  ossicula 
chalcoidea. 

2  Os  cuneiforme  internum,  primum,  or 
magnum. 


3  Os  cuneiforme  medium,  secundum,  or 
minus. 

4  Os  cuneiforme  externum,  or  tertium. 

5  Collum  pedis ;  neck  of  the  foot. 


156  THE   SKELETON. 

outer  part  of  the  tarsus,  between  the  astragalus  and  calcaneum,  is  a  large 
space  or  sinus,1  which  narrows  into  a  canal,  proceeding  obliquely  inward 
and  backward  to  the  inner  side  of  the  tarsus.  Both  sinus  and  canal  are 
occupied  by  interosseous  ligaments  connecting  the  astragalus  and  cal- 
caneum. Back  of  the  astragalus  a  groove  is  observable,  leading  toward 
another  beneath  the  lateral  process  of  the  calcaneum,  both  of  which 
accommodate  the  tendon  of  the  long  flexor  of  the  great  toe. 

The  articulation  of  the  astragalus  and  calcaneum  with  the  other  bones 
of  the  tarsus  is  so  nearly  in  a  direct  line,  that  it  affords  a  convenient 
position  for  disarticulation,  when  necessary,  from  injuries  of  the  foot. 

BONES  OF  THE  METATARSUS. 

The  Metatar'sal  bones,2  or  those  composing  the  metatarsus,3  corre- 
spond in  number  with  the  toes,  which  they  join  in  front.  They  are 
enumerated  from  within  outward,  have  the  same  general  construction  as 
the  metacarpal  bones,  and  are  slightly  bent  in  their  length  so  as  to  con- 
tribute to  the  concavity  of  the  sole  of  the  foot. 

The  shaft  is  trilateral ;  one  surface  presenting  downward,  another  out- 
ward, and  the  third  inward  and  upward.  The  shaft  of  the  outer  four 
bones  gradually  narrows  to  its  head ;  that  of  the  great  toe  is  more  uni- 
form in  diameter. 

The  posterior  extremity,  or  base,  is  the  most  expanded  part,  is  quad- 
rate, and  varies  in  form  with  the  different  bones.  The  base  of  the  first, 
at  its  lower  part,  has  a  tubercle  for  the  insertion  of  the  long  peroneal 
tendon ;  the  bases  of  the  succeeding  three  are  wedge  shaped,  and  by 
their  lateral  adaptation  contribute  to  the  convexity  of  the  back  and  the 
concavity  of  the  sole  of  the  foot.  The  base  of  the  last  metatarsal  is 
prolonged  outward  and  backward  into  a  tuberosity  for  the  insertion  of 
the  short  peroneal  tendon.  The  bases  of  the  outer  four  metatarsals  ar- 
ticulate with  one  another  by  opposed  smooth  surfaces :  those  of  the  inner 
three  metatarsals  articulate  with  the  cuneiform  bones ;  and  those  of  the 
outer  two  with  the  cuboid  bone. 

The  anterior  extremity,  or  head,  is  constructed  like  the  correspond- 
ing part  of  the  metacarpal  bones,  but  is  smaller,  in  proportion  with  the 
length  of  the  bones,  except  in  the  case  of  that  of  the  great  toe. 

The  first  metatarsal  bone  is  the  shortest,  but  is  twice  as  robust  as  the 
others ;  the  second  and  fifth  metatarsals  are  the  longest,  and  are  nearly 
equal ;  the  third  and  fourth  are  next  in  length,  and  are  also  nearly  equal. 
All  the  metatarsals  lie  parallel  to  one  another,  and  they  contribute  in 

1  Sinus  tarsi.  2  Ossa  metatarsi. 

3  Metatarsium;  metapedium ;  prsecordium,  solum,  or  vestigium  pedis. 


THE   SKELETON.  157 

their  union  to  the  convexity  of  the  back  and  the  concavity  of  the  sole  of 
the  foot.  The  interos'seous  spaces  are  enumerated  from  within  out- 
ward. 

BONES  OF  THE  TOES. 

The  Toes1  are  enumerated  from  within  outward,  as  the  first  or  great 
toe,2  the  second,  third,  fourth,  and  fifth  or  little  toe.  They  diminish 
in  length  from  first  to  last,  and  possess  the  same  number  of  bones  as 
the  fingers.  The  phalanges,3  or  joints,  of  the  toes  have  the  same 
general  form  as  those  of  the  fingers,  but  are  smaller,  except  those  of  the 
great  toe,  which  are  as  long  and  of  more  robust  proportions  than  those 
of  the  thumb. 

In  the  first  row  of  phalanges,  except  in  the  great  toe,  the  shaft  resem- 
bles that  of  the  corresponding  bones  of  the  fingers,  but  compressed  later- 
ally so  as  to  assume  a  more  cylindroid  form. 

In  the  second  and  third  rows  of  phalanges  of  the  outer  two  or  three 
toes,  the  characteristic  extremities  are  so  nearly  approached  that  the 
shaft  is  more  or  less  obsolete.  The  second  and  third  phalanges  of  the 
little  toe  are  frequently  co-ossified. 

The  two  ses'amoid  bones  of  the  great  toe  are  like  those  of  the  thumb, 
and  occupy  a  corresponding  position  in  the  sole  of  the  foot. 

THE  FOOT. 

The  Foot  is  placed  at  a  right  angle  with  the  leg,  and  rests  upon 
the  ground  with  the  tuberosity  of  the  calcaneum,  the  heads  of  the 
metatarsal  bones,  and  the  under  parts  of  the  phalanges.  The  heel  pro- 
jects behind  the  leg  at  the  outer  part  of  the  foot,  of  which  it  is  the  nar- 
rowest portion.  From  the  fore  part  of  the  tarsus,  or  the  instep,  the  foot  in 
advance  gradually  expands  in  breadth  and  becomes  thinner.  The  upper 
or  dorsal  surface,  or  back  of  the  foot,  is  convex  in  its  length  and 
breadth  ;  and  the  under  or  plantar  surface,  or  sole,  in  the  same  direction 
is  concave.  The  arch  formed  by  the  foot  is  higher  and  more  open  on  the 
inner  side.  When  covered  with  soft  parts,  the  heel,  outer  border  of  the 
foot,  and  the  under  part  of  the  toes  touch  the  ground  ;  the  inner  archway 
constituting  the  hollow  of  the  foot.  The  feet  of  the  two  sides  diverge 
from  each  other  in  front,  in  consequence  of  the  rotary  muscles  of  the 
thigh  directing  the  limbs  outwardly.  The  hinge-like  joint  of  the  ankle 


1  Digiti  pedis.  2  p0Uex  pedis ;  hallux,  or  hallus. 

3  Ossa,  articuli,  or  internodia  digitorum  pedis. 


158  THE   SKELETON. 

allows  flexion  and  extension  of  the  foot.  In  the  former  movement  the 
foot  is  bent  forward ;  in  the  latter  the  back  of  the  foot  approaches  the 
same  line  as  the  front  of  the  leg.  The  movement  of  the  foot  directing 
its  sole  inward  and  in  a  feebler  degree  outward,  occurs  between  the  astra- 
galus and  the  tarsal  bones  with  which  it  articulates.  The  bones  of  the 
tarsus  and  metatarsus  together  exhibit  but  very  little  movement  among 
themselves,  with  the  exception  just  mentioned.  The  toes  present  a 
greater  degree  of  extension  upon  the  metatarsus  than  the  fingers  on  the 
metacarpus,  but  their  power  of  flexion  is  much  more  limited,  and  that 
of  abduction  and  adduction  are  feeble.  The  phalanges  of  the  toes  have 
the  same  movements  among  themselves  as  those  of  the  fingers,  but  are 
restricted  from  their  comparatively  feeble  development.  A  continuance 
of  extension  of  the  toes  flexes  the  foot ;  the  reverse  action  of  the  toes 
extends  the  foot.  When  the  toes  are  covered  with  their  soft  parts,  the 
second  appears  a  little  longer  than  the  first,  a  feature  which  has  not 
escaped  the  attention  of  artists,  but  the  great  toe  of  the  skeleton  is 
actually  the  longer. 

DEVELOPMENT  OF  THE  BONES  OF  THE  LOWER  EXTREMITY. 

The  femur  begins  to  ossify  about  the  middle  of  the  second  month  of 
embryonic  life,  being  earlier  than  the  vertebral  column.  At  birth  its 
shaft  is  formed,  and  an  ossific  centre  has  appeared  in  the  lower  extremity 
as  an  epiphysis.  Subsequently  the  head,  the  greater  and  the  smaller 
trochanter  successively  ossify  as  epiphyses. 

The  patella  is  formed  from  a  single  centre  of  ossification,  appearing 
several  years  after  birth. 

The  shaft  of  the  tibia  commences  ossification  about  the  same  time  as 
that  of  the  femur,  and  the  shaft  of  the  fibula  begins  the  process  a  little 
later.  In  both  bones,  after  birth,  the  extremities  ossify  as  epiphyses. 

The  astragalus  and  calcaneum  begin  to  ossify  before  birth  ;  the  other 
tarsal  bones  subsequently.  An  epiphysis  is  developed  upon  the  tuber- 
osity  of  the  calcaneum.  The  metatarsal  and  phalangial  bones  are  ossi- 
fied in  the  same  manner  as  the  corresponding  bones  of  the  hand. 

ARTICULATIONS   AND   MOVEMENTS   OF  THE   LOWER 
EXTREMITIES. 

The  support  of  the  trunk  of  the  body  requires  that  the  articulations 
of  the  lower  extremities  should  be  more  extensive,  and  stronger  than 
those  of  the  upper  extremities,  a  condition  which  has  been  gained 
at  the  expense  of  comparative  freedom  in  movement.  The  hip  bones, 


THE   SKELETON. 


159 


described  as  part  of  the  trunk,  but  which  correspond  with  the  bones  of 
the  shoulder,  are  entirely  immovable. 


FIG.  118. 


THE  HIP  JOINT. 

The  Hip  joint,1  formed  between  the  acetabulum  and  the  head  of  the 
thigh  bone,  is  the  strongest  articulation  of  the  body,  and  the  best  instance 
of  a  ball-and-socket  joint.  Though  admitting  of  movement  in  every 
direction,  it  is  nevertheless  much  restricted  in  this  respect  in  comparison 
with  the  shoulder  joint. 

The  acetabulum  is  deepened  by  a  prismatic  fibro-cartilaginous  ring, 
the  eot'yloid  lig'ament,2  at- 
tached around  its  margin. 
As  the  ligament  passes  over 
the  cotyloid  notch,  this  is 
converted  into  a  foramen, 
which  transmits  articular  ves- 
sels into  the  joint. 

From  the  pit  on  the  head 
of  the  femur,  a  strong  fibrous 
cord,  the  round  lig'ament,3 
diverges  inwardly  to  be  at- 
tached to  the  margins  of  the 
cotyloid  notch. 

The  cap'sular  lig'ament4 
of  the  hip  joint  is  the  strong- 
est one  of  the  body.  It  is 
attached  by  its  upper  extrem- 

ity  around   the  border  Of  the    iliac  ligament;  2,  the  greater  sacro-sciatic  ligament;  3,  the 

acetabulum,  inclosing  the  CO-    lesser  8^ro-sciatic  ligament;  4,  the  greater  sacro-sciatic  fora- 

0  f         men;  5,  the  lesser  sacro-sciatic  ligament;  6,  the  cotyloid  liga- 

tyloid  ligament;  aild  by  its  ment  surrounding  the  acetabulum;  7,  the  round  ligament  ;  8, 
lower  extremitV  is  attached  attacnment  of  the  capsular  ligament  of  the  hip  joint  to  the 

neck  of  the  femur  ;  9,  obturator  membrane. 

to  the  anterior  mter-trocnan- 

teric  ridge  of  the  femur,  and  less  strongly  to  the  neck  of  the  latter  just 
above  the  posterior  inter-trochanteric  ridge.  In  front  of  the  joint  it  is 
strengthened  by  a  broad  fibrous  band,  the  accessory  lig'ament,5  which 
is  extended  between  the  anterior  inferior  spinous  process  of  the  ilium  and 
the  anterior  inter-trochanteric  ridge.  The  capsular  ligament  is  surrounded 


portion  of  the  pogterior  gacr(> 


1  Coxo-  or  ilio-femoral  articulation. 

2  Labrum  cartilagineum. 

3  Lig.  teres ;  interarticular  ligament. 


4  Membrana  capsularis  femoris. 

6  Superior  ligament;  ilio-femoral  liga- 


ment. 


160 


THE   SKELETON. 


with  large  muscles,  which  contribute  to  the  strength  of  the  joint.  Intern- 
ally it  is  lined  with  synovial  membrane,  which  also  invests  the  neck  of  the 
femur,  and  is  reflected  upon  the  round  ligament. 

Even  when  all  the  muscles,  together  with  the  capsular  ligament  sur- 
rounding the  hip  joint,  are  cut  away,  it  requires  considerable  force  to 
remove  the  head  of  the  femur  from  its  socket,  in  consequence  of  the 
pressure  of  the  atmosphere  retaining  it  in  position. 


FIG.  119. 


THE  KNEE  JOINT. 

The  Knee  joint  is  the  largest  and  most  complex  of  the  articulations. 
It  is  hinge  like  and  slightly  rotary  in  its  movements.     It  allows  the  leg 

to  be  almost  doubled  in  flexion  on  the 
back  of  the  thigh,  but  permits  its  exten- 
sion only  to  a  straight  line  with  the  latter. 
When  the  leg  is  flexed  the  articulation  of 
the  knee  permits  it  to  rotate  moderately 
on  its  axis  from  side  to  side,  but  not  when 
in  the  extended  condition. 

The  condyles  of  the  femur  and  tibia, 
with  a  pair  of  interposed  fibro-cartilages, 
and  the  patella,  form  the  basis  of  the 
joint;  the  contiguous  surfaces  of  the 
bones  being  invested  with  cartilage.  It 
is  enveloped  in  a  thin  capsular  ligament 
lined  with  an  extensive  synovial  mem- 
brane, and  is  strengthened  by  strong  cord- 
like  ligaments  and  the  contiguous  ten- 
dons of  muscles. 

Upon  the  condyles  of  the  tibia  rest  the 
semilu'nar  fi'bro-cartilages,1  a  pair  of 
prismoid,  C-like  plates,  with  their  ex- 
tremities attached  in  front  and  back  of 
the  spinous  process.2  Their  exterior 
border  is  thick,  and  they  slope  off  to  a 

thin  interior  edge,  by  which  arrangement  they  deepen  the  shallow  ar- 
ticular surfaces  of  the  tibia  into  suitable  concavities  for  the  play  of  the 


THE  RIGHT  KNEE  JOINT,  laid  open  from 
the  front.  1,  articular  surface  of  the  fe- 
mur; 2,  3,  crucial  ligaments;  4,  inser- 
tion of  one  of  these  ligaments  into  the 
tibia;  5,  attachment  of  the  alar  folds  of 
the  synovial  membrane  to  the  femur ;  6, 
7,  internal  and  external  sernilunar  fibro- 
cartilages;  8,  ligament  of  the  patella 
turned  down,  so  as  to  exhibit  the  syno- 
vial bursa  (9)  beneath;  10,  superior  ti- 
bio-fibular  articulation ;  11,  interosseous 
membrane. 


1  Fibro-cartilagines,  or  cartilagines 
semilunares,  interarticulares,  falcatse, 
lunatae,  meniscoideae,  or  sigraoideae. 


2  The  attachments  of  these  fibro-carti- 
lages constitute  the  ligamenta  cartilagi- 
num  serailunatarum.  A  connection  of 
the  two  in  front,  the  lig.  transversum. 


THE  SKELETON. 


161 


FIG.  120. 


condyles  of  the  femur.  The  inner  fibro-cartilage  is  adherent  by  its  cir- 
cumference to  the  capsular  and  lateral  ligaments ;  the  outer  one  is  not  so 
much  adherent,  and  therefore  glides  more  freely  to  and  fro  with  the  move- 
ments of  the  femur.  Besides  adapting  the  condyles  of  the  tibia  to  those 
of  the  femur,  the  semilunar  nbro-cartilages  protect  the  condyles  from 
attrition,  act  as  elastic  cushions  to  reduce  the  force  of  concussions,  and 
prevent  the  atmosphere  from  pressing  the  capsular  ligament  between,  the 
bones. 

From  the  sides  of  the  intercondyloid  fossa  of  the  femur  a  pair  of 
strong,  fibrous  cords,  the  cru/cial  lig'a- 
ments,1  cross  each  other  and  descend  to 
be  attached  in  front  and  behind  the  spinous 
process  of  the  tibia.  These  ligaments  re- 
strict the  flexion  and  extension  of  the  leg, 
and  give  firmness  to  the  joint,  especially 
when  the  limb  is  flexed. 

The  cap'sular  lig'ament2  is  a  thin,  capa- 
cious envelope,  attached  to  the  rough  borders 
of  the  condyles  of  the  femur  and  tibia,  and 
the  sides  of  the  patella,  and  associated  with 
the  tendons  of  the  various  muscles  attached 
in  the  vicinity  of  the  articulation.  It  is  so 
thin  as  to  appear  to  be  a  mere  continuation 
of  the  periosteum  of  the  contiguous  bones 
strengthened  at  particular  points  with  pro- 
cesses from  neighboring  tendons.  A  pro- 
cess3 of  this  kind,  at  the  back  of  the  joint, 
is  derived  from  the  tendon  of  the  semi-mem- 
branous muscle,  and  is  extended  between  the 
external  condyle  of  the  femur  and  the  internal  condyle  of  the  tibia. 

Above  the  patella,  the  tendon  of  the  quadriceps  extensor  occupies 
position  and  function  of  a  strong  ligament  to  the  knee  joint;  below  is 
the  lig'ament  of  the  patella,4  a  broad,  thick,  fibrous  band,  which  is 
an  extension  of  the  tendon  of  the  muscle  just  mentioned  descending 
from  the  apex  and  front  of  the  patella  to  the  tuberosity  of  the  tibia. 
Just  above  its  insertion  the  ligament  is  separated  from  the  head  of  the 
tibia  by  a  synovial  bursa,  not  communicating  with  the  knee  joint. 


FRONT  VIEW  OF  THE  RIGHT  KNEE 
JOINT.  1,  tendon  of  the  quadriceps 
extensor  muscle ;  2,  patella ;  3,  liga- 
ment of  the  patella,  or  tendinous  in- 
sertion of  the  muscle  just  mentioned ; 
4,  capsular  ligament;  5,  6,  internal 
and  external  lateral  ligaments;  7, 
superior  tibio-fibular  articulation. 


1  L.  cruciata. 

2  Membrane  capsularis  genu. 


3  Lig.  posticum  Winslowii ;    1.  popli- 
teum ;  posterior  ligament. 

4  Lig.  patellae. 


11 


162 


THE  SKELETON. 


FIG.  121. 


The  internal  lateral  ligament1  of  the  knee  joint  is  a  long,  broad,  and 

strong  band,  extended  between  the 
tuberosity  of  the  internal  condyle 
of  the  femur  and  the  upper  part  of 
the  inner  border  of  the  tibia.  The 
external  lateral  ligament2  is  a 
rounded  cord,  extended  between 
the  tuberosity  of  the  external  con- 
dyle of  the  femur  and  the  head  of 
the  fibula.  These  ligaments  sus- 
tain the  firmness  of  the  articulation, 
more  especially  in  the  extended  con- 
dition of  the  leg. 

The  synovial  membrane  of  the 
knee  joint  lines  the  capsular  liga- 
ment, and  is  reflected  upon  the 
semilunar  nbro-cartilages  and  cru- 
cial ligaments.  It  is  also  reflected 
upon  a  mass  of  fat  intervening  be- 
tween the  ligament  of  the  patella 
and  the  front  of  the  head  of  the 
tibia,  and  is  extended  along  the 
sides  of  the  joint  as  two  crescentic 
appendages  named  the  a'lar  folds.3 
These  unite  and  are  prolonged  in 
a  conical,  cord-like  process,4  ascending  obliquely  backward,  to  be 
.attached  to  the  front  margin  of  the  intercondyloid  fossa  of  the  femur. 
Above  the  patella  and  its  trochlea  the  synovial  membrane  is  reflected  as 
a  pouch  for  several  inches  upward,  between  the  tendon  of  the  quadriceps 
extensor  and  the  femur.  In  the  flexion  of  the  leg  this  pouch  is  drawn 
down  to  the  edge  of  the  trochlea  of  the  femur ;  and  in  extension  is  again 
drawn  up  by  fleshy  slips5  of  the  quadriceps  muscle.  Behind  the  joint, 
the  synovial  membrane  extends  upward  between  the  condyles  of  the 
femur  and  the  tendinous  heads  of  the  origin  of  the  gastrocnemius  muscle. 


LONGITUDINAL  SECTION  OF  THE  LEFT  KNEE  JOINT. 
1,  femur;  2,  tendon  of  the  quadriceps  extensor 
muscle;  3,  patella;  4,  ligament  of  the  patella;  5, 
tibia ;  6,  synovial  bursa ;  7,  cushion  of  fat  occupy- 
ing the  angular  interval  between  the  patella  and 
head  of  the  tibia;  ******  reflections 
of  the  synovial  membrane ;  8,  pouch  of  this  mem- 
brane extending  upward  between  the  tendon  of  the 
quadriceps  extensor  and  the  front  of  the  femur ;  9, 
the  outer  alar  fold  of  the  synovial  membrane;  10, 
connection  of  the  alar  folds  with  the  femur;  11, 
crucial  ligament;  12,  back  of  the  capsular  liga- 
ment. 


1  L.  laterale  internum. 

2  L.  laterale  externum. 

3  Ligamenta  alaria ;  1.  alare  majus  in- 
ternum et  minus  externum. 


4  Mucus   ligament;    ligamentum  mu- 
cosum. 

5  Musculi  subcrurales  ;  m.  articulares 
genu. 


THE  SKELETON. 


163 


FIG.  122. 


THE  TIBIO-FIBULAR  ARTICULATIONS. 

The  fibula  articulates  immovably  with  the  tibia. 
"he  superior  tib'io-fib'ular  articulation,1  between  the  head  of  the 

>r  and  the  outer  condyle  of  the  kfct- 
£er,  has  the  opposed  surfaces  covered  with 
cartilage.  It  is  inclosed  in  a  capsular  liga- 
ment, the  stronger  portions  of  which  consti- 
tute the  anterior  and  posterior  ligaments. 

The  wide  interval  between  the  two  bones 
of  the  leg  is  occupied  by  an  interos'seous 
membrane,2  composed  of  parallel  fibres  de- 
scending obliquely  from  the  outer  border  of 
the  tibia  to  the  opposed  border  of  the  fibula. 
The  membrane  is  perforated  above  for  the 
passage  of  the  anterior  tibial  vessels.  It 
gradually  narrows  below,  and  between  the 
inferior  extremities  of  the  bones  consists  of 
short,  strong  fibres3  firmly  connecting  them 
together. 

The  inferior  tib'io-fib'ular  articulation 
is  strengthened  by  the  anterior  ligament,4 
which  is  an  oblique  band  extending  from 
the  front  of  the  tibia  downward  to  the  ex- 
ternal malleolus;  and  the  posterior  ligament,5  which  consists  of  two 
bands  pursuing  the  same  course  behind  the  bones. 


POSTERIOR  VIEW  OF  THE  INFERIOR 

TIBIO-FIBULAR  AND   ANKLE  JOINTS.      1, 

interosseous  membrane;  2,  3,  two 
fasciculi  of  the  posterior  tibio-fibular 
ligament;  4,  iuternal  lateral  liga- 
ment of  the  ankle  joint ;  5,  6,  poste- 
rior and  outer  fasciculi  of  the  exter- 
nal lateral  ligament;  7,  capsular 
ligament  of  the  ankle  joint;  8,  cal- 
caueum. 


THE  ANKLE  JOINT. 

The  Ankle  joint6  is  formed  by  the  transverse  arch  between  the  malleoli 
and  the  body  of  the  astragalus.  It  is  a  simple  hinge-like  articulation, 
permitting  flexion  and  extension. 

The  joint  is  surrounded  by  a  thin  cap'sular  lig'ament,  connecting  the 
contiguous  borders  of  the  articular  surfaces  of  the  bones,  strengthened 
by  lateral  ligaments. 


1  Pereneo-tibial  articulation. 

2  Membrana  interossea ;  septum  longi- 
tudinale  interosseum. 

3  Inferior  interosseous  ligament. 

4  L.  tibio-fibulare  anticum  superius  et 
inferius;  1.  malleoli  interni  anticum. 


5  L.  tibio-fibulare  posticum  superius  et 
inferius;    the  posterior  and  transverse 
ligaments ;  1.  malleoli  interni  anticum. 

6  Articulatio  pedis  ;    articulatio  talo- 
cruralis. 


164 


THE  SKELETON. 


The  external  lateral  ligament1  consists  of  three  strong  fibrous  bands 
diverging  from  the  outer  malleolus;  one  proceeding  backward  to  the 
posterior  border  of  the  astragalus,  a  second  descending  to  the  outer  part 
of  the  calcaneum,  and  the  third  passing  forward  to  the  anterior  border  of 
the  astragalus. 


FIG.  123. 


FIG.  124. 


EXTERNAL  VIEW  OF  THE  RIGHT  ANKLE  JOINT.    1,  INTERNAL  VIEW  OF  THE  ANKLE  JOINT.    1,  internal 

tibia;  2,  external  malleolus  of  the  fibula ;  3,  astra-  malleolus  of  the  tibia;   2,  astragalus;   3,  calca- 

galus ;  4,  calcaneum ;  5,  cuboid  bone ;  6,  7,  8,  three  neum ;   4,  scaphoid  bone ;   5,  internal  cuneiform 

fasciculi  of  the  external  lateral  ligament;  9, front  bone;  6,  internal  lateral  ligament;  7,  capsular  lig- 

of  the  capsular  ligament.  ament ;  8,  Achilles'  tendon. 

The  internal  lateral  ligament2  is  a  strong  band  diverging  from  the 
lower  border  of  the  inner  malleolus  to  the  corresponding  side  of  the 
astragalus  and  the  lateral  process  of  the  calcaneum. 


THE  INTERTARSAL  AND  TARSO-METATARSAL  ARTICULA- 
TIONS. 

ARTICULATIONS   OP   THE   ASTRAGALUS,  CALCANEUM,  AND   SCAPHOID   BONE. 

The  astragalus  and  calcaneum  are  conjoined  by  a  thick  interos'seous 
lig'ament,  occupying  the  sinus  formed  by  the  contiguous  grooves  of 
those  bones.  The  ligament  separates  two  joints,  of  which  the  poste- 
rior is  surrounded  by  a  short,  thin  cap'sular  lig'ament,  lined  with  a 
synovial  membrane.  The  other  joint  is  continuous  inferiorly  with 
that  between  the  head  of  the  astragalus  and  the  scaphoid  bone ; 
both  being  enveloped  in  a  common  cap'sular  lig'ament,  and  lined 
with  a  continuous  synovial  membrane.  This  articulation  is  strength- 
ened above  by  a  broad  fibrous  band,  the  astrag'alo-scaph'oid  lig'a- 


1  L.  laterale  externum  ;  1.  fibulare  tali 
posticum  et  anticum  et  1.  fibulare  calca- 
nei;  1.  malleoli  extern!  posticum,  medium, 


et  auticum ;  1.  fibulae  posticum,  medium, 
et  anticum. 

2  L.  laterale  internum  ;  1.  deltoides  ;  1. 
tibio-tarsium. 


THE  SKELETON. 


165 


ment  i1  at  its  outer  side  by  the  external  calcan'eo-scaph'oid  ligament,2 
connecting  the  corresponding  bones  in  the  interval  between  the  astraga- 
lus and  cuboid  bone.  Below  the  articulation  is  the  inferior  calcan'eo- 
scaph'oid  ligament,3  which  is  a  strong,  broad  band  proceeding  from  the 
lateral  process  of  the  calcaneum,  beneath  the  head  of  the  astragalus,  to 
the  scaphoid  bone. 

ARTICULATION  OF  THE  CALCANEUM  AND  CUBOID  BONE. 

The  intervening  articulation  of  the  calcaneum  and  cuboid  bone  is  sur- 
rounded by  a  short  cap'sular  lig'ament,  strengthened  above  and  below 
by  a  broad  band  of  fibres  constituting  the  superior  and  inferior  calcan'- 
eo-cu/boid  lig'ament.4 


LIGAMENTS  OF  THE  SOLE  OF  THE 
FOOT.  1,  calcaneum;  2,  astraga- 
lus; 3,  scaphoid  bone  ;  4,  long 
plantar  ligament;  5,  inferior  cal- 
caneo-cuboid  ligament;  6, inferior 
calcanec-scaphoid  ligament;  7, 
plantar  ligaments  between  the 
cuneiform  bones  and  base  of  the 
metatarsus ;  8,  tendon  of  the  long 
peroneal  muscle  passing  through 
a  groove  of  the  cuboid  bone 
above  the  long  plantar  ligament 
to  be  inserted  into  the  first  meta- 
tarsal  bone;  9,  capsular  ligament 
between  the  latter  and  the  inter- 
nal cuneiform  bone;  10,  plantar 
ligaments,  having  the  same  rela- 
tionship with  the  metatarso-pha- 
langial  and  phalangial  articula- 
tions that  the  palmar  ligaments 
have  with  the  corresponding 
joints  of  the  fingers ;  11,  lateral 
ligaments;  12,  transverse  liga- 
ments; 13,  lateral  ligaments  of 
the  phalangial  articulations. 


FIG.  125. 


ARTICULATION  OF  THE  SCAPHOID,  CUBOID,  AND  CUNEIFORM 
BONES  TOGETHER  AND  WITH  THE  BASES  OF  THE  META- 
TARSAL  BONES. 

All  the  bones  here  mentioned,  with  the  exception  of  the  first  metatar- 
sal,  are  joined  with  one  an- 
other, on  the  back  and  sole 
of  the  foot,  by  fibrous  bands 
associating  those  contiguous, 
and  constituting  the  dor'sal 
and  plan'tar  lig'aments,5 
which  together  form  a  sort 
of  capsular  ligament. 

Interos'seous  lig'aments,6 
consisting  of  short  interven- 
ing fibres,  conjoin  the  scaph- 
oid with  the  cuboid  bone,  the 
latter  with  the  external  cunei- 
form bone,  the  three  cunei- 
form bones  with  one  another, 
and  the  bases  of  the  outer 
four  metatarsal  bones. 

The  synovial  membrane  of 
the  articulation  of  the  scaphoid  and  cuneiform  bones  is  prolonged  to  that 


1  L.  astragalo-scaphoideum. 

2  L.  calcaneo-scaphoideum  externum, 
interosseum,    or    dorsale ;    1.  calcaneo- 
naviculare  interosseum. 

3  L.  calcaneo-scaphoideum  inferius  ;  1. 
calcaneo-naviculare  plantare. 


4  L.  calcaneo-cuboideum   superius   et 
inferius,  or  dorsale  et  plantare,  or  breve. 

5  L.  dorsalia  et  plantaria. 

6  L.  interossea. 


166  THE  SKELETON. 

of  the  cuboid  and  external  cuneiform  bone,  and  also  to  the  articulation 
between  the  outer  two  cuneiform  and  the  second  and  third  metatarsal 
bones.  Another  synovial  membrane  lines  the  joint  of  the  cuboid  and 
outer  pair  of  metatarsal  bones. 

The  first  metatarsal  bone  and  internal  cuneiform  bone  form  a  separate 
joint  surrounded  by  a  capsular  ligament  with  a  distinct  synovial  mem- 
brane. 

The  Long  Plan'tar  lig'ament,1  the  most  conspicuous  of  the  ligaments 
of  the  foot,  commences  on  the  under  surface  of  the  calcaneum,  and 
proceeds  forward,  gradually  expanding,  to  be  attached  to  the  tuberosity 
of  the  cuboid  bone  and  the  bases  of  the  last  two  metatarsal  bones.  It 
converts  the  groove  of  the  cuboid  bone  into  a  canal,  through  which 
passes  the  tendon  of  the  long  peroneal  muscle. 

METATARSO-PHALANGIAL  AND  PHALANGIAL  ARTICULA- 
TIONS. 

The  metatar'so-phalan'gial  and  phalan'gial  articulations  are  con- 
structed exactly  like  the  corresponding  joints  of  the  hand. 

1  L.  longum-plantae ;  1.  calcaneo-cuboideum  plantare ;  inferior  or  long  calcaneo- 
cuboid  ligament. 


CHAPTER  III. 

THE    FIBROUS,   CARTILAGINOUS,    FIBRO-CARTILAG1NOUS,  ELASTIC,    AND 
ADIPOSE    TISSUES. 

IN  describing  the  articulations  of  the  skeleton,  many  structures  were 
mentioned,  which  enter  into  their  composition,  in  addition  to  the  bones.  As 
these  structures  likewise  enter  into  the  constitution  of  many  other  parts 
of  the  body,  it  has  appeared  to  us  convenient  to  defer  an  examination 
of  their  nature  until  the  present  moment.  Those  to  which  we  espe- 
cially refer  are  the  fibrous,  cartilaginous,  fibro-cartilaginous,  and  elastic 
tissues.  To  these  we  might  add  the  serous,  adipose,  and  muscular  tissues, 
but  an  account  of  the  former  and  latter  will  be  deferred  to  other  oppor- 
tunities ;  while  the  adipose  tissue,  which  appears  to  be  unessential  to  the 
constitution  of  any  organ,  may  be  conveniently  described  in  the  present 
chapter. 

FIBROUS  TISSUE. 

Fi'brous  tis'sue1  is  one  of  the  most  abundant  and  extensively  diffused 
materials  of  structure  of  the  body.  It  mainly  composes  the  dermis  or 
true  skin;  the  superficial  and  deep  fascia;  the  periosteum  and  perichon- 
drium ;  nearly  all  the  ligaments  ;  the  sheaths  of  blood-vessels  and  nerves ; 
the  tendons,  aponeuroses,  and  sheaths  of  muscles ;  the  dura  mater,  sclero- 
tica,  and  the  outer  layer  of  the  pericardium ;  the  capsules  of  the  spleen, 
kidneys,  testes  and  ovaries ;  the  submucous,  subserous,  and  subglandular 
tissues  ;  and  the  general  connective  or  areolar  tissue  of  most  organs  of 
the  body. 

Fibrous  tissue  is  white,  bluish  white,  or  yellowish  white,  and  more  or 
less  glistening.  When  dried  it  becomes  hard,  yellow,  and  transparent ; 
but  assumes  its  former  appearance  on  the  imbibition  of  water.  It  is 
the  strongest  and  most  tenacious  of  all  animal  tissues,  is  very  inex- 
tensible,  but  highly  flexible.  From  these  physical  properties  it  is  admi- 
rably adapted  to  the  various  purposes  for  which  it  is  employed  in  the 

1  White  fibrous  tissue. 

(167) 


168 


THE   TISSUES. 


body,  viz.,  the  protection,  sustaining,  and  connection  of  other  tissues  and 
organs. 


FIG.  127. 


FIG.  126. 


EXAMPLE  OF  FIBROCS  TISSUE.  Portion  of  one  of 
the  lateral  ligaments  of  a  phalangial  articulation, 
exhibiting  its  composition  of  bundles  of  parallel 
filaments  of  fibrous  tissue ;  highly  magnified. 


EXAMPLES  OF  FIBROUS  TISSUE.  1,  a  small  tendin- 
ous cord  from  the  right  ventricle  of  the  heart.  The 
upper  extremity  exhibits  its  division  and  expan- 
sion into  the  edge  of  the  tricuspid  valve.  2,  a  por- 
tion of  the  dura  mater  of  the  spinal  cord. 


The  great  strength,  tenacity,  and  durability  of  fibrous  tissue  have  ren- 
dered it  of  important  service  in  the  arts.  The  so-called  "cat-gut,"  fiddle 
strings,  and  the  like,  are  the  twisted  fibrous  structure  of  the  small  intes- 
tine of  the  sheep.  All  varieties  of  leather  consist  of  the  fibrous  derm 
of  the  skins  of  animals,  rendered  less  liable  to  the  ordinary  causes  of 
decay  by  union  with  certain  chemical  substances,  such  as  tannin.  Parch- 
ment is  likewise  derived  from  the  same  source ;  and  the  savage  finds  it 
invaluable  as  a  bow-string. 

By  boiling  fibrous  tissue  it  is  resolved  into  gelatin ;  and  hence  frag- 
ments of  skin,  tendons,  and  ligaments  are  the  chief  source  of  the  glue  of 
commerce. 

Fibrous  tissue  is  mainly  composed  of  exceedingly  fine  homogeneous 
filaments,  measuring  from  the  3^3  to  tne  TDUOTJ  °f  an  incn  *n  diameter, 
collected  into  minute  inextensible  bundles,  which  may  be  associated  into 
larger  bundles,  as  in  the  formation  of  tendons  and  ligaments,  or  they 
may  interlace  with  one  another  into  more  or  less  extensible  membranes. 
The  intervals  of  the  bundles  of  filaments  of  fibrous  tissue  are  occupied 
by  a  colorless  homogeneous  liquid  resembling  serum,  but  its  exact  nature 
has  not  been  positively  determined. 


THE   TISSUES. 


169 


FIG.  128. 


All  structures  of  fibrous  tissue  contain  more  or  less  intermingled 
elastic  tissue  in  the  char- 
acter of  slender  fusiform 
fibres,  or  as  fine  net- 
works. The  elastic  tis- 
sue is  rendered  evident, 
on  treating  portions  of 
any  of  the  fibrous  struc- 
tures with  acetic  acid, 
beneath  the  microscope. 
By  this  process  the 
fibrous  tissue  is  ren- 
dered so  transparent  as 
to  appear  indistinct, 
while  the  fibres  of  the 
elastic  tissue  become 
sharply  defined. 

In    the   formation   of 
tendons,     the     primary 
bundles  of  fibrous  tissue  are  closely  associated  parallel  to  one  another, 
thus    producing    strong    inexten- 
sible  cords,  admirably  adapted  to 
convey  the  muscular  power  to  the 
bone  or  other  part  to  be  moved. 
Likewise  in  the  construction  of  the 
band-like   ligaments,    intended    to 
unite  the  bones   in  the  strongest 
manner,  the  fibrous  tissue  is   col- 
lected into  parallel  bundles,  per- 
mitting   free    flexibility,    but    no 
stretching  or  extensibility. 

In  the  constitution  of  aponeu- 
roses,  the  deep  fascia,  and  the 
dura  mater,  bundles  of  fibrous  tis- 
sue are  arranged  parallel  to  one 
another  in  layers,  and  crossed  by 
bundles  which  closely  associate  the 
former  together. 

In  most  other  fibrous  structures, 
the  filaments  and  bundles  of  fibrous 
tissue  interlace  with  one  another  in 
such  a  manner  as  to  permit  of  more  or  less  extensibility. 


1,  PORTION  OF  CONNECTIVE  TISSUE,  from  that  which  envelops 
the  flexor  tendons  of  the  fingers  as  they  pass  beneath  the  annular 
ligament,  treated  with  acetic  acid.  The  pale,  dotted  portion  is  in- 
tended to  represent  the  fibrous  element  fading  away ;  the  blacker 
tortuous  lines  and  nets  represent  the  mixture  of  elastic  tissue.  2, 
3,  simple  tortuous  fibres,  and  a  net  of  elastic  tissue,  isolated  from 
the  preceding  specimen. 


FIG.  129. 


FIBROUS  TISSUE.  1,  portion  of  tendon  exhibiting 
its  composition  of  prismatic  bundles  of  fibrous  tis- 
sue, the  filaments  all  parallel  to  one  another ;  2, 
a  few  bundles  drawn  from  the  others,  exhibiting 
their  union  by  delicate  crossing  filaments  of  con- 
nective tissue,  (3)  one  of  the  varieties  of  fibrous  tis- 
sue; 4,  a  single  bundle,  more  highly  magnified, 
with  a  portion  (5)  of  the  filaments  fretted  out. 


This  property 


170 


THE   TISSUES. 


is,  however,  entirely  dependent  on  the  arrangement  alone  of  the  fibrous 
tissue,  as  it  is  in  all  cases  entirely  inextensible  in  the  direction  of  its  fila- 
ments. The  fact  may  be  easily  understood  by  referring  to  a  familiar 
illustration :  thus,  while  a  handkerchief  or  other  similar  fabric  is  inexten- 
sible in  the  direction  of  its  threads,  it  is  quite  extensible  and  contractile 
diagonally  to  the  course  of  those  threads,  or  in  the  bias  direction,  as  it  is 
usually  termed. 

Simply  by  the  arrangement  then  of  the  filaments  of  fibrous  tissue,  we 
find  in  the  body  structures  composed  of  it  exhibiting  every  degree  of 
softness  and  extensibility,  from  the  delicate,  cottony  connective  tissue,  to 
the  unyielding  tendon. 

Connective  or  are'olar  tis'sue,1  found  almost  everywhere  in  the  body 
in  the  form  of  a  moist,  tough,  white,  downy  substance,  is  composed  of 


FIG.  130. 


FIG.  131. 


PORTION  OF  CONNECTIVE  TISSUE,  from  the  axilla, 
exhibiting  its  composition  of  bundles  and  filaments 
of  fibrous  tissue  crossing  in  every  direction.  The 
rounded  bodies  represent  a  single  row  and  a  por- 
tion of  a  small  group  of  fat  cells. 


CROSSING  BANDS  OF  FIBROUS  TISSUE,  from  the  ex- 
ternal, or  fibrous  coat  of  the  facial  artery.  Inter- 
vals are  left  in  the  drawing  to  exhibit  clearly  that 
there  are  two  layers  of  fibrous  tissuo,  of  which  the 
filaments  cross  one  another  in  their  spiral  course 
around  the  vessels. 


interlacing  bundles  of  fibrous  tissue,  and  of  all  materials  is  the  best 
adapted,  from  its  combined  strength,  softness,  and  yielding  character,  to 
connect,  sustain,  and  strengthen  organs,  while  it  permits  a  certain  degree 
of  mobility  among  them.  Thus  it  tenaciously  holds  together  the  vessels, 


1  Cellular  tissue ;  tela  cellulosa,  or  cellularis;  reticulated,  filamentous,  laminated, 
or  porous  tissue ;  cellular,  or  reticular  substance ;  context  us  cellulosus ;  ethmyphe, 
tela  Hippocratis  cribrosa. 


THE  TISSUES.  171 

nerves,  muscles,  bones,  and  skin,  fills  up  intervals  and  forms  soft  beds  of 
support  for  them,  and  yet  allows  them  moderate  freedom  of  movement. 
In  like  manner  it  holds  together  the  muscular  fibres,  the  nerve  fibres,  and 
the  constituents  of  other  tissues,  and  gives  them  strength  without  incon- 
veniently impeding  their  movements.  Comprising  as  it  does  the  submu- 
cous  and  subserous  layers  of  the  hollow  viscera,  while  these  derive  from 
it  their  main  strength,  it  yet  permits  their  expansion. 

In  the  sheath  of  blood-vessels  and  muscular  fasciculi,  the  filaments 
of  fibrous  tissue  cross  one  another  diagonally  to  the  course  of  the 
former  in  a  most  beautiful  manner,  and  while  they  give  strength  they 
allow  movement  in  all  directions.  While  the  band-like  ligaments,  com- 
posed of  parallel  bundles  of  fibrous  tissue,  firmly  unite  the  bones  and  are 
simply  flexible,  the  capsular  ligaments,  composed  of  interlacing  bundles 
of  the  same  material,  are  moderately  extensible.  The  tendon,  composed 
of  closely  parallel  bundles  of  fibrous  tissue,  does  not  stretch,  but  follows 
the  contraction  of  the  muscle  whose  swelling  form  is  observed  through 
the  more  yielding  fasciae  and  skin. 

The  fibrous  tissues  are  furnished  with  comparatively  few  and  small 
blood-vessels ;  the  large  arteries  and  veins  frequently  observed  in  them, 
as  for  instance  in  the  submucous  tissues  and  the  dura  mater,  being  des- 
tined to  supply  the  contiguous  structures.  The  nerves  are  also  few,  and 
hence  the  sensibility  of  these  tissues  is  of  the  feeblest  character.  The 
dermis  would  appear  to  be  an  exception  in  comparison  with  other  fibrous 
structures,  but  the  vessels  and  nerves  in  this  case  are  rather  intended  for 
the  functions  of  various  accessory  parts,  as  for  example  the  papilla  of 
touch  and  of  the  hairs,  the  glands,  and  the  epidermis. 

Fibrous  tissue,  of  all  others,  appears  to  be  the  most  easily  reproduced 
in  cases  where  it  has  been  destroyed.  It  forms  the  structural  element  of 
most  cicatrices,  false  membranes,  adhesions,  etc. 


CARTILAGE  AND  FIBRO-CAETILAGE. 

Car'tilage  or  gristle1  is  a  dense  substance,  of  less  hardness  than  bone, 
of  a  bluish-white  or  yellow  color,  with  an  opalescent  or  pearly  appear- 
ance. It  is  elastic,  flexible  but  inextensible,  and,  though  of  firm  consist- 
ence, is  less  tough  than  fibrous  tissue.  Easily  cut  or  sliced  with  the 
knife,  in  thin  pieces  it  is  translucent  j*ttird  to  the  naked  eye  appears 
homogeneous  in  structure.  By  drying  it  becomes  very  hard,  yellow,  and 

1  Cartilage ;  chondros. 


172 


THE  TISSUES. 


FIG.  132. 


CARTILAGE;  section  through  the  thickness  of  the 
oval  cartilage  of  the  nose.  1,  toward  the  exterior ; 
2,  toward  the  interior  surface ;  highly  magnified. 
It  exhibits  groups  of  cartilage  cells  imbedded  in  a 
homogeneous  or  faintly  granular  matrix. 


transparent,  but  readily  assumes  its  former  condition  through  the  imbibi- 
tion of  water. 

From  its  physical  properties  cartilage  is  admirably  adapted  to  con- 
tribute to  the  formation  of  the  joints 
of  the  skeleton,  and  to  give  form 
and  strength  to  other  organs,  with- 
out too  great  a  degree  of  rigidity. 
It  constitutes  the  articular  carti- 
lages, the  cartilages  of  the  ribs, 
those  of  the  larynx,  except  the  epi- 
glottis, those  of  the  trachea  and  its 
divisions,  and  those  of  the  nose. 
In  association  with  fibrous  tissue  it 
forms  the  fibro-cartilages,  as  the 
intervertebral  disks,  the  fibro-car- 
tilages of  the  symphyses,  the  inter- 
articular  fibro-cartilages,  the  epi- 
glottis, the  cartilages  of  the  ear  and  Eustachian  tube,  and  those  of  the 
eyelids. 

The  bones  originate,  for  the  most  part,  in  the  condition  of  cartilage, 
and  to  a  much  less  degree  in  the  form  of  fibrous  tissue ;  and  their  subse- 
quent development  and  growth  are  step  by  step  preceded  by  a  produc- 
tion of  the  latter  tissues.  The  cartilages  which  ossify  and  form  part  of 
the  skeleton  are  commonly  termed  temporary  cartilages ;  although  the 
others,  named  in  contradistinction  permanent  car'tilages,  in  many  cases 
at  a  later  period  of  life  become  ossified,  or  show  more  or  less  disposition 
to  do  so.  Thus  the  cartilages  of  the  larynx  may  become  completely 
ossified,  and  the  costal  cartilages  are  liable  to  partial  ossification.  The 
articular  cartilages,  the  cartilages  of  the  nose,  and  the  fibro-cartilages 
exhibit  no  tendency  to  ossification,  at  least  under  ordinary  circum- 
stances. 

In  structure,  cartilage  consists  of  a  solid  matrix  with  imbedded  nucleated 
cells.  The  matrix  is  colorless  and  translucent,  or  resembles  in  appearance 
ground  glass,  or  it  is  faintly  amber  colored.  It  is  amorphous,  indis- 
tinctly granular,  or  obscurely  filamentous,  passing  into  a  distinctly  fib- 
rous condition.  The  nucleated  cells  may  be  single,  but  are  usually  in 
compressed,  elongated  oval  groups,  which  seem  as  if  they  had  origin- 
ated through  the  division  of  simple  cells,  as  they  are  seen  in  the  earliest 
condition  of  cartilage.  In  the  deeper  part  of  the  articular  cartilages, 
and  the  more  interior  part  of  the  others,  the  groups  of  cells  are  ar- 
ranged vertically  to  the  direction  of  the  free  surfaces ;  but,  approaching 
the  latter,  they  become  more  numerous  and  parallel  to  them.  The  car- 


THE   TISSUES. 


173 


tilage  cells  are  observable  from  single  ones  up  to  groups  of  twenty  or 
more.  They  have  more  or  less  thickened  walls,  with  faintly  granular 
contents,  usually  a  nucleus,  and  frequently  one  or  more  oil  globules. 


FIG.  134. 


FIG.  133. 


VERTICAL  SECTION  OP  ARTICULAR  CARTILAGE,  from 
the  carpal  surface  of  the  radius.  1,  2.^3,  articular 
cartilage;  below  this  is  a  portion  of  the  hone,  5,  6, 
7.  1,  exterior  portion  of  the  cartilage,  exhibiting 
the  groups  of  cells  lying  parallel  to  the  slightly 
irregular  free  surface ;  2,  3,  the  cells  arranged  ver- 
tically in  the  deeper  part  of  the  cartilage ;  4,  groups 
of  cells  obscured  by  osseous  deposits  ;  5,  structure 
of  the  bone,  exhibiting  the  concentric  laminae,  and 
lacuna?;  6, a  vascular  canal;  7,  a  marrow areola  of 
the  spongy  substance  of  the  bone.  The  specimen 
is  highly  magnified,  but  the  depth  of  the  articular 
cartilage  is  proportionately  reduced,  so  as  to  ex- 
hibit the  relation  of  all  the  parts  without  making 
too  large  a  figure. 


SECTION  OF  COSTAL  CAHTILAGE.  The  upper  part  is 
toward  the  exterior  surface,  where  the  groups  of 
cells  are  arranged  parallel  to  it;  the  lower  part 
is  toward  the  interior,  where  the  groups  are  ar- 
ranged vertically  to  the  free  surfaces ;  highly  mag- 
nified. 


Fi'bro-car'tilage  consists  of  a 
more  or  less  dense  fibrous  matrix, 
with  imbedded  cartilage  cells.  Be- 
tween pure  fibrous  tissue  and  pure 
cartilage  we  may  distinguish  very 
various  degrees  of  intermixture  of 
the  two  elements  in  the  constitution  of  the  fibro-cartilages.  Thus  the 
cartilages  of  the  eyelids,  and  the  semilunar  and  other  interarticular  carti- 
lages, are  almost  entirely  composed  of  fibrous  tissue.  This  is  likewise 
the  case  with  the  exterior  of  the  intervertebral  disks,  but  the  more 
pulp-like  central  portion  contains  numerous  mingled  cartilage  cells.  In 
the  cartilages  of  the  ear  and  the  epiglottis  a  more  equal  admixture  of 
the  two  elements  is  observable,  groups  of  cells  being  contained  in  the 
meshes  of  an  intricate  intertexture  of  fibres.  Even  in  the  costal  carti- 
lages, classed  with  the  pure  cartilages,  portions  of  the  interior  not  un- 
frequently  present  a  decidedly  fibrous  matrix,  including  the  cell  groups. 


174 


THE   TISSUES. 


Fibro-cartilages  combine  the  elasticity  of  cartilage  with  the  tenacity 
of  fibrous  tissue,  and  are  well  adapted  for  the  firmest  union  of  bones, 
accompanied  with  a  moderate  degree  of  flexibility. 


FIG.  135. 


FIG.  136. 


SECTION  OF  COSTAL  CARTILAGE,  crossing  the  free  surfaces,  but  tiiken  from  near  the  centre.  To  the 
left,  which  was  toward  the  exterior  surface,  the  groups  are  imbedded  in  a  homogeneous  matrix;  toward 
the  right,  the  matrix  has  assumed  a  decidedly  fibrous  character.  Specimen  from  an  adult  of  about  forty 
years  of  age. 

By  long  boiling  cartilage  is  resolved  into  chondrin,  a  substance  resem- 
bling gelatin,  but,  unlike  it,  is  precipitable  by  the  mineral  acids.  The  mine- 
ral salts  of  cartilage  are  like  those 
of  bone,  and  amount  to  about  three 
and  a  half  parts  in  the  hundred. 
Fibro-cartilage  by  boiling  is  re- 
solvable, into  gelatin. 

The  articular  cartilages  consist 
of  thin  layers  covering  the  artic- 
ular surfaces  of  bones  in  the  con- 
struction of  movable  joints.  They 
are  entirely  non-vascular,  and  de- 
void of  nerves;  but  they  derive 
nourishment  from  the  blood-vessels 
in  contact  with  their  surface  beneath 
or  continuous  with  the  bones.  The 
other  cartilages  are  invested  with  a  fibrous  membrane,  named  the  peri- 
chon/drium,  which  serves  as  a  means  of  attachment  with  contiguous 
parts,  and  as  a  nidus  to  the  blood-vessels  nourishing  the  cartilages.  The 
comparatively  thick  costal  cartilages  are  pervaded  with  vascular  canals, 
continuous  with  those  of  the  ribs,  and  contain  nutrient  vessels  com- 
municating with  those  of  the  latter  and  of  the  perichondrium.  Fibre- 
cartilages  receive  more  vessels  than  the  true  cartilages,  but  the  num- 
ber of  them  is  very  small. 


SECTION  OF  FIBRO-CARTILAGE  FROM  THE  AURICLE 
OF  THE  EAR.  The  cells  are  seen  imbedded  in  a 
fibrous  matrix.  1,  exterior  surface,  where  the  cells 
are  parallel  to  it ;  2,  toward  the  middle.  Highly 
magnified. 


THE  TISSUES. 


175 


FIG.  137. 


ELASTIC  TISSUE. 

The  Elas'tic  tissue,1  though  widely  distributed  in  the  body,  seldom  forms 
masses  of  any  important  size.  It  composes  the  yellow  ligaments  of  the  ver- 
tebral arches ;  is  the  chief  component  of  the  thyro-hyoid  ligament,  the 
vocal  membrane,  and  the  structure  conjoining  the  rings  of  the  trachea 
and  bronchia ;  and  it  enters  largely,  in  association  with  muscular  tissue, 
in  the  formation  of  the  middle  coat  of  the  blood-vessels.  In  small  quan- 
tity it  is  found  mingled  with  most  of  the  fibrous  structures,  as  the  der- 
mis,  the  superficial  fasciae,  etc. 

In  its  most  striking  condition  of  development  it  is  observed  composing 
the  nuchal  ligament  of  quadrupeds,  especially  the  more  bulky  ones,  as 
the  elephant,  elk,  and  the  ox,  in  which,  through  its  elasticity,  it  sustains 
the  weight  of  the  head,  and  thus  economizes  muscular  power.  In  the 
same  animals  it  also  constitutes  a  strong  layer  in  the  abdominal  wall, 
where  it  sustains  the  pressure  of  the  contained  viscera. 

Elastic  tissue  in  its  ordinary  condition  is  dull  yellow,  opaque,  tough, 
and  coarsely  fibrous.  Yiewed  by  means  of  the 
microscope,  it  is  found  to  be  composed  of  re- 
ticulating fibres,  the  abruptly  broken  ends  of 
which  appear  curled.  The  fibres  vary  exceed- 
ingly in  diameter  in  different  parts  of  the 
body.  Those  found  in  the  subserous  or  sub- 
mucous  tissues  form  nets  of  filaments  almost  as 
fine  as  those  of  fibrous  tissue.  Those  of  the 
yellow  ligaments  of  the  vertebrae  measure 
about  the  goVo  °f  an  ^ncn  ^n  diameter.  Fi- 
nally, in  the  middle  coat  of  the  blood-vessels 
the  elastic  tissue  in  part  consists  of  wide  reticu- 
lar  bands,  together  having  the  appearance  of  a 
perforated  membrane.2 

In  the   formation  of  ligaments  and   mem- 
branes, the  bundles  of  elastic  tissue  composing     ELASTIC  TISSUE' highly  masnifled> 

0    from  the  yellow  ligaments  of  the 

them  are  associated  by  areolar  tissue,  and  the  vertebra.  The  specimen  is  observed 
former  also  are  invested  with  the  same  material  to  be  composed  of  coarse  anastomos- 

ing  fibres. 

as  the  latter. 

Long  boiling  resolves  elastic  tissue  into  a  brownish  liquid,  which  smells 
like  glue,  but  does  not  form  a  jelly  on  cooling. 

The  structures  composed  of  elastic  tissue  are  furnished  with  few  blood- 
vessels, the  capillaries  of  which  pursue  the  general  course  of  the  fibres 


1  Yellow  elastic  tissue.       2  Perforated,  or  fenestrated  membrane ;  striated  membrane. 


176 


THE   TISSUES. 


of  the  former.     The  supply  of  nerves  is  small,  and  little  is  known  in 
regard  to  them. 


FIG.  138. 


FIG.  139. 


ELASTIC  TISSUE,  from  the  middle  coat  of  the  pul- 
monary artery  of  the  horse;  highly  magnified. 


ELASTIC  TISSUE,  from  the  middle  coat  of  the  ca- 
rotid artery  of  the  horse;  highly  magnified. 


ADIPOSE  TISSUE. 

Ad'ipose  or  fat  tis'sue  is  remarkable  as  a  physical  element  of  the  body, 
from  the  fact  that  it  does  not  appear  to  be  essential  to  the  constitution 
of  any  organ.  'Its  quantity  depends  much  upon  the  condition  of  health, 
habits  of  life,  and  other  circumstances  of  the  individual ;  in  certain  dis- 
eases, or  from  starvation,  disappearing  almost  entirely ;  in  healthy  per- 
sons frequently  adding  greatly  to  the  bulk  of  the  body,  and  sometimes 
accumulating  to  such  an  extent  as  in  the  condition  itself  to  be  viewed  as 
a  disease.  It  exists  generally  wherever  connective  tissue  is  found,  occu- 
pying the  areolae  of  the  latter,  and  filling  the  interspaces  of  organs,  thus 
contributing  to  the  symmetry  of  form  of  the  body. 

Examined  microscopically,  adipose  tissue  is  observed  to  consist  of 
masses  of  delicate,  transparent  vesicles,  distended  with  a  liquid,  yellow- 
ish fat.  From  mutual  pressure  the  fat  vesicles  are  polyhedral,  but  when 
isolated  are  spherical  and  of  variable  diameter,  but  average  the  7  J^  of 
an  inch.  They  consist  of  nucleated  cells,  the  nuclei  of  which  are  attached 
to  the  walls  of  the  latter,  and  are  rendered  invisible  by  the  presence  of 
the  contained  oil.  In  emaciated  or  dropsical  subjects  these  cells  may 
often  be  detected  with  the  nucleus  distinctly  visible,  and  with  the  cell 
contents  consisting  of  a  serous  liquid  and  one  or  more  drops  of  yellow  oil. 

Adipose  tissue  forms  a  considerable  and  continuous  layer1  beneath  the 
skin,  lodged  in  the  meshes  of  the  dermis  and  in  the  adjacent  connective 
tissue.  In  this  position  it  is  most  abundant  in  the  female,  contributing 


1  Panniculus  adiposus. 


THE   TISSUES. 


177 


mainly  to  her  characteristic,  rounded  symmetry  of  form.  It  is  especially 
thick  beneath  the  skin  of  the  breast,  abdomen, 
and  buttocks.  In  the  palms  of  the  hands  and 
soles  of  the  feet,  it  serves  as  an  elastic  cushion 
to  relieve  the  influence  of  pressure,  and  is 
always  present,  even  under  the  greatest  ex- 
tent of  emaciation.  Mostly  it  is  confined  to 
the  subcutaneous  layer  of  the  superficial  fascia, 
and  only  when  excessive  does  it  pervade  the 
deeper  layer  of  the  same  fascia. 

The  adipose  tissue  also  occupies  the  inter- 
vals of  muscles,  the  hollows  of  the  temples  and 
cheeks,  and  the  interspaces  of  the  important 
organs  of  the  orbits.  The  disappearance  of 
this  material  in  disease  gives  rise  to  the  sunken 
appearance  of  the  eyes,  the  cheeks,  and  the 

temples.  ADIPOSE  TISSUE,  WITH  CONNECTIVE 

Adipose  tissue  also  collects  along  the  course  TISSUE> from  the  8UPerficial  fascia  of 

r  .  the    abdomen;     highly    magnified. 

of  the  blood-vessels  and  nerves,  especially  those  The  groups  of  fat  vesicles  are  ob- 
of  the  heart  and  intestines.  It  often  accumu-  served  contained  **  the  meshes  of 

connective  tissue. 

lates  in  large  quantity  around  the  kidneys  and 

the  lower  extremity  of  the  rectum,  and  between  the  folds  of  the  perito- 
neum ;  according  to  its  extent  in  these  positions  producing  in  a  great 
measure  the  protuberant  abdomen  of  fat  persons.  It  likewise  constitutes 
the  marrow  of  the  medullary  cavities  of  bones,  fills  up  intervals  about 
the  joints,  and  occupies  the  synovial  folds  ;  but  surrounding  the  articula- 
tions it  is  usually  in  less  quantity  than  elsewhere  subjacent  to  the  skin. 

In  the  healthy  condition,  no  adipose  tissue  exists  in  the  subcutaneous 
connective  tissue  of  the  eyelids,  and  of  the  penis  and  scrotum.  It  also 
does  not  exist  in  the  submucous  connective  tissue ;  nor  is  it  found  in  the 
interior  of  the  cranium,  the  dura  mater  of  the  spinal  cord,  the  eyeball, 
or  the  lungs. 

The  blood-vessels  of  the  adipose  tissue  form  a  capillary  net,  with 
polyhedral  meshes,  including  the  fat  vesicles.  Nerves  are  transmitted  to 
important  structures  through  adipose  tissue,  but  appear  to  give  it  no 
branches. 


12 


FIG.  141. 


CHAPTER  IV. 

THE   MUSCULAR   SYSTEM. 

THE  Mus'cles1  are  the  principal  organs  of  motion  in  animals.  They 
constitute  the  greater  portion  of  the  human  body,  and  in  an  important 
degree  contribute  to  the  production  of  its  outward  form.  They  are 
numerous,  of  very  different  sizes,  and  of  various  shapes,  dependent  in 
some  measure  upon  the  position  they  occupy.  They  consist  of  a  soft, 
red,  fleshy  part,  named  the  belly,2  usually  attached,  by  means  of  ten'dons, 
between  two  or  more  points  of  the  skeleton.  The  substance  of  the  mus- 
cular belly,  named  flesh  or  mus'cle,  is  the  active  agent  of  motion,  while 

the  tendons  are  entirely 
passive,  simply  communi- 
eating  the  power  of  the 
former  to  the  part  to  be 
moved. 

FIG.  142. 


TRANSVERSE  SECTION  or  THE  LOWER  END  OF  THE  ULNO-CARPAL 
FLEXOR,  moderately  magnified,  a,  section  of  tendon  appearing  as 
two  crescents,  composed  of  prismatic  fasciculi  of  fibrous  tissue; 
ft.  a  secondary  fasciculus  of  crescentic  shape,  consisting  of  primary 
bundles  of  muscular  fibres;  c,  a  flattened  cylindrical  secondary 
fasciculus,  consisting  of  primary  bundles  of  muscular  fibres;  d, 
secondary  and  primary  bundles  in  outline ;  e,  sheath  of  the  mus- 
cle, composed  of  fibrous  tissue. 


TRANSVERSE  SECTION  OF  A  MUSCULAR 
FASCICULUS,  exhibiting  its  prismoid 
form,  and  its  composition  of  pris- 
matic muscular  fibres.  From  the 
biceps  flexor  of  the  arm.  Highly  mag- 
nified. 


The  belly  of  a  muscle  is  composed  of  an  aggregation  of  peculiar,  soft, 
red  fibres,  named  mus'cular  fi'bres.3  These  are  collected  into  primary 
bundles,  or  fascic'uli,4  which  are  associated  into  larger  or  secondary 
fascic'uli,  and  these  again  may  unite  in  the  formation  of  still  coarser 
bundles,  as  those  of  the  great  gluteal  muscle.  The  fibres  and  fasciculi 


1  Musculi.  Singular :  musculus ;  lacer- 
tus ;  torus ;  mys. 

2  Venter,  or  medium  musculi. 

(178) 


3  Fleshy  fibres.    Sing.:  fibrum  muscu- 
lare ;  fibrilla  muscularis. 

4  Lacerti  musculorum. 


THE   MUSCULAR   SYSTEM. 


179 


FIG.  143. 


are  held  together  and  enveloped  with  delicate  connective  tissue,  the  fila- 
ments of  which  cross  one  another  diagonally  to  the  direction  of  the 
former,  as  represented  in  figure  143,  so  as  to  interfere  in  the  least  degree 
with  muscular  movement.  The  prismatic  form  of  the  fibres  and  fasciculi 
enables  them  to  give  the  most  com- 
pact condition  to  the  muscles,  and 
thus  economize  space. 

In  some  muscles  the  fasciculi  run 
parallel  to  one  another  through- 
out the  length  of  the  former,  as  in 
the  sartorius  and  gracilis  muscles. 
In  others,  they  converge  from  one 
attachment  to  the  other,  producing 
a  triangular  or  ra'diated  mus'cle,1 
as  in  the  temporal  and  pectoral 
muscles.  In  some,  the  fasciculi 
converge  toward  both  attachments, 
as  in  the  biceps  flexor  of  the  arm. 
In  others,  the  fasciculi  converge 
from  each  side  of  a  muscle  to  a 
median  tendon,  producing  what  is 
called  a  pen/niform  mus'cle,2  from 
its  resemblance  in  arrangement  to 
a  feather,  as  in  the  rectus  muscle  of 
the  thigh,  or  the  dorsal  interosseous 
muscles  of  the  hand.  When  the 
fasciculi  of  a  muscle  proceed  ob- 
liquely from  one  attachment  to  a 
tendon  on  the  other  side,  a  semi-pen/niform  mus'cle  is  produced,3  as  in 
the  case  of  the  peroneal  muscles  of  the  leg. 

From  their  extent,  muscles  are  often  mentioned  as  long,  short,  and 
broad  muscles;  from  their  form,  as  triangular,  quadrate,  terete  or 
rounded,  fusiform,  and  ribbon-like  muscles ;  and  from  the  direction  of 
their  fasciculi,  as  straight,  oblique,  and  transverse  muscles. 

The  point  of  attachment  of  a  muscle  from  which  it  ordinarily  acts  is 
called  its  origin,  and  the  corresponding  extremity  of  the  muscle  is  named 
its  head,  The  point  of  attachment  which  is  to  be  moved  is  called  the  in- 
sertion. Generally,  the  origin  is  the  point  of  attachment  nearest  the  vert- 
ebral column.  Functionally,  the  origin  and  insertion,  if  these  be  viewed 
as  the  fixed  and  moving  points,  will  vary  according  to  the  circumstances  in 


TWO   PORTIONS  OP  A  MUSCULAR  FASCICULUS,  from 

the  trapezius  muscle;  highly  magnified.  1,  two  por- 
tions of  a  muscular  fasciculus,  composed  of  pris- 
matic striated  fibres  terminating  below,  in  rounded 
extremities,  among  the  fibrous  tissue  of  the  com- 
mencing tendon ;  2,  cut  extremities  of  the  fibres, 
showing  their  prismatic  form;  3,  delicate  sheath 
composed  of  obliquely  crossing  filaments  of  fibrous 
tissue ;  4,  the  fibres  of  the  commencing  tendons. 
Partly  a  diagram. 


1  M.  radiatus.  2  M.  penniformis ;  m.  pennatus.  3  M.  semi-penniformis. 


180  THE   MUSCULAR   SYSTEM. 

which  the  body  is  placed.  Thus,  the  muscles  emanating  from  the  trunk 
and  shoulders,  which  ordinarily  raise  the  arms,  by  fixing  the  latter,  may 
be  made  to  raise  the  body,  as  instanced  in  the  experiment  of  elevating 
the  head  to  the  level  of  a  horizontal  bar  placed  above  it. 

The  number  of  points  of  attachment  of  muscles  varies,  and  thus  the 
latter  are  said  to  arise  by  one,  two  or  more  heads,  as  the  case  may  be. 
Prom  the  number  of  heads,  the  muscles  are  mentioned  as  single  headed, 
biceps,  triceps,  and  many  headed.  The  number  of  insertions  likewise 
vary,  a  muscle  with  a  single  head  not  unfrequently  ending  in  a  number 
of  tendons  of  insertion,  as  in  the  common  extensor  of  the  fingers. 

The  names  of  the  muscles  are  derived  from  some  prominent  character, 
as  the  position,  direction,  form,  attachments,  number  of  heads,  or  physi- 
ological action. 

The  ten'dons  or  sinews1  vary  in  character,  some  consisting  of  the 
shortest  attachment  of  the  muscular  belly  to  the  points  of  origin  and 
insertion,  while  some  are  spread  out  in  broad  membranous  expansions, 
named  aponeuro'ses,2  and  others  form  strong,  flattened,  cylindrical  cords. 
They  are  bluish  or  yellowish  white,  longitudinally  striated,  and  glisten- 
ing; and  are  very  flexible  but  entirely  inextensible.  In  their  connection 
with  the  muscular  bellies  they  usually  commence  in  the  interior  as  a  wide 
expansion,  or  upon  the  exterior  as  an  aponeurotic  facing.  From  the 
belly,  the  tendons  may  continue  with  the  same  width  to  their  origin  and 
insertion,  but  frequently  become  gradually  narrowed  into  flattened,  cylin- 
dricalcords. 

As  relates  to  the  more  intimate  structure  of  the  muscles,  an  examina- 
tion of  both  the  muscular  and  tendinous  tissue  is  required. 

FIG.  144. 


Two  MUSCULAR  FIBRES,  from  the  lower  end  of  the  ulno-carpal  flexor ;  highly  magnified.  To  the  right 
of  the  figure,  the  muscular  substance  is  observed  to  be  gradually  resolved 'among  the  fibrous  tissue  of  the 
commencing  tendon. 

The  muscular  fibres,  viewed  with  the  microscope,  are  found  to  be 
of  variable  diameter,  though  uniform  in  each  case,  and  they  average 
about  the  ^1—  of  an  inch.  They  appear  moderately  translucent,  pale 

1  Leaders;  thews.     Sing.:  tendo;  tenon;  pronervatio. 

2  Sing. :   expansio  nervosa ;   denervatio ;  pronervatio. 


THE   MUSCULAR   SYSTEM. 


181 


reddish,  faintly  striated  longitudinally,  and  distinctly  and  regularly  stri- 
ated transversely,  whence  the  name  applied  to  them  of  striated  muscu- 
lar fibres,1  in  contradistinction  to  those  of  the  hollow  viscera,  which  for 
the  most  part  are  unstriated. 

A  further  analysis  of  the  muscular  fibres  proves  each  to  consist  of  a 
bundle  of  numerous  and  exceedingly  minute  filaments,  named  muscular 
fi'brils,  inclosed  together  in  a  delicate  wall  of  structureless  membrane 
called  the  myolem'ma.2  The  muscular  fibrils  are  composed  of  highly 
refractive  particles3  of  uniform  size  and  arrangement,  to  which  is  due 
the  regularly  transverse  striated  appearance  of  the  muscular  fibres. 


FIG.  146. 


FIBRILS  FROM  A  MUSCULAR  FIBRE  OF  THE  AXOLOTL, 
a  batrachian  reptile ;  highly  magnified,  a,  Bundle 
of  fibrils;  b,  an  isolated  fibril. 


A  MUSCULAR  FIBRE  OF  A  SALAMANDER,  a  batrachian 
reptile,  which  had  been  long  kept  in  weak  alcohol. 
1,  muscular  substance ;  2,  nuclei ;  3,  muscular  sub- 
stance split  into  disks ;  4,  the  myolemma. 


Occasionally  the  latter  are  broken  in  the  direction  of  their  transverse 
stria?,  when  they  appear  as  if  composed  of  a  series  of  superimposed 
disks,  as  represented  in  figure  146. 

The  muscular  fasciculi,  in  approaching  their  tendinous  connections,  be- 
come pointed,  from  one  muscular  fibre  after  another  ceasing  in  the  ten- 
dinous structure.  In  many  instances  the  muscular  fibres  terminate  in 
rounded  or  bluntly-pointed  extremities,  but  in  other  instances  the  fibrils 
of  the  fibres  appear  gradually  to  resolve  themselves  among  the  tendinous 
structure. 


1  Striped  muscular  fibres.  2  Sarcolemma. 

3  Myoline ;  sarcous  element,  matter,  or  substance. 


182  THE   MUSCULAR   SYSTEM. 

When  treated  with  acetic  acid  the  muscular  fibres  are  rendered  more 
translucent,  and  a  number  of  elongated  nuclei,  imbedded  among  the 
fibrils,  are  brought  into  view.  These  nuclei  remain  from  the  organic 
cells,  from  which  the  muscular  fibres  were  originally  developed. 

Muscular  fibres  possess  the  property  named  contractility,  which  is 
excited  ordinarily  during  life  through  impressions  received  from  the  ner- 
vous system,  though  a  variety  of  stimuli,  as  mechanical  irritation,  chem- 
ical agencies,  change  of  temperature,  and  electricity,  are  capable  of  call- 
ing it  into  action.  By  this  property  the  muscles  shorten  or  contract, 
and  thus  by  approaching  the  two  extremities  move  the  insertion.  When 
the  contraction  ceases,  the  muscles  again  become  elongated,  and  the  con- 
tractile power  is  lost  only  with  the  death  of  the  muscular  tissue.  With 
the  contraction  there  is  a  corresponding  increase  of  bulk  in  the  breadth 
and  thickness  of  the  muscle.  When  muscular  fibres  are  observed  con- 
tracting beneath  the  microscope,  the  transverse  striae  are  observed  to 
approach  more  closely,  while  the  fibres  increase  their  diameter. 

When  muscles  are  inserted  into  soft  organs,  they  usually  have  no  ten- 
dinous attachment,  but  their  fibres  resolve  themselves  into  the  contiguous 
parts,  as  in  the  insertion  of  the  muscles  around  the  mouth. 

The  tendons  are  composed  of  dense  bundles  of  fibrous  tissue,  the  fila- 
ments of  which  are  associated  with  one  another  in  a  perfectly  parallel 
manner.  In  the  thicker  tendons  the  finer  bundles  are  collected  into 
coarser  prismatic  fasciculi,  associated  by  a  looser  texture  of  the  same 
material,  forming  their  connective  tissue.  From  the  parallel  arrange- 
ment of  the  fibrous  structure  of  the  tendons  they  are  rendered  inexten- 
sible,  which  quality,  together  with  their  great  strength  and  small  size, 
admirably  adapts  them  to  communicate  the  power  of  the  comparatively 
bulky  muscular  belly  not  only  to  distant  parts,  but  also  to  very  limited 
points  of  insertion. 

The  muscles  are  invested  with  fibrous  sheaths,  continuous  with  those 
of  the  muscular  fasciculi  and  with  one  another.  Portions  of  these 
sheaths  between  muscles  in  many  instances  present  a  tendinous  or  apo- 
neurotic  character,  constituting  the  so-called  internmscular  partitions, 
from  which  the  muscles  in  part  frequently  arise.  The  groups  of  muscles 
in  different  regions  of  the  body  are  enveloped  together  in  fibrous 
sheaths,  named  the  fas'cise,  as  the  brachial  fascia,  the  femoral  fascia,  etc. 
These  fasciae  are  usually  denser  or  more  aponeurotic  in  their  character 
than  the  sheaths  of  the  individual  muscles.  In  many  instances  the  latter 
partly  arise  from  the  fasciae,  or  are  partly  and  even  wholly  inserted  into 
them. 

To  preserve  the  position  of  tendons  in  their  course  they  are  frequently 
confined  in  grooves,  or  upon  narrow  surfaces  of  the  bones,  by  means  of 


THE   MUSCULAR   SYSTEM.  183 

appropriate  ligaments,  as  in  the  passage  of  the  extensor  tendons  through 
grooves  at  the  carpal  extremity  of  the  radius,  and  the  passage  of  the 
flexor  tendons  of  the  fingers  beneath  the  annular  ligament  of  the  wrist 
and  the  vaginal  ligaments  of  the  phalanges. 

When  muscles  or  their  tendons  pass  over  prominences  of  the  bones, 
thin  walled,  serous  pouches,  named  syno'vial  bur'sae,1  intervene,  with 
the  object  of  alleviating  friction.  Similar  bursae  are  reflected  upon  ten- 
dons as  they  pass  through  grooves  or  beneath  annular  and  vaginal  liga- 
ments. In  some  instances  these  bursae  are  much  divided  or  folded,  as  in 
the  reflection  of  the  synovial  bursa  upon  the  flexor  tendons  of  the 
fingers  as  they  pass  beneath  the  annular  ligament  of  the  wrist. 

When  muscles  are  accidentally  torn,  they  are  not  restored  by  the  re- 
production of  muscular  tissue,  but  the  parts  are  reunited  by  means  of 
ordinary  fibrous  tissue. 

The  muscles  are  highly  vascular,  in  accordance  with  their  great 
activity.  Their  capillary  blood-vessels  generally  pursue  a  course  parallel 
to  and  between  the  muscular  fibres,  and  frequently  anastomose  across 
the  latter.  The  tendons  are  but  slightly  vascular.  The  lymphatic  ves- 
sels are  few  in  the  muscles,  and  have  not  been  detected  in  the  tendons. 

Though  possessing  only  a  moderate  degree  of  sensibility,  the  muscles 
are  abundantly  supplied  with  nerves,  their  office,  however,  being  mainly 
to  convey  motor  impressions.  The  terminal  branches  of  the  nerves  anas- 
tomose with  one  another  and  form  intricate  plexuses  among  the  muscular 
fibres.  The  tendons  are  almost  devoid  of  nerves,  and,  at  least  in  a  con- 
dition of  health,  are  entirely  insensible. 

GENERAL  REMARKS  ON  THE  HEAD. 

The  Head2  is  composed  of  the  skull  with  its  contents,  covered  with 
muscles  and  the  skin.  The  cranial  vault  is  covered  with  the  occipito- 
frontal,  temporal,  and  auricular  muscles,  and  the  scalp.  The  front  of  the 
cranium  is  the  forehead,  its  back  the  occiput,  and  its  sides  the  temples  or 
tem/poral  regions.  The  forehead3  terminates  below  with  the  eyebrows 
and  the  intervening  space,  named  glabel/la ;  on  each  side  is  bounded 
by  the  temple,  and  above  by  the  scalp.  The  occiput4  extends  between 
the  position  of  the  ears  posteriorly,  and  is  covered  at  its  lower  part  by 
the  muscles  of  the  neck.  The  temple,5  so  called  from  the  Latin  tempus, 
time,  because  in  this  region  white  hairs  first  appear,  is  defined  above  by 
the  course  of  the  temporal  ridge,  below  by  the  zygoma. 

1  Bursse  mucosse.  4  Occipitum  ;  regio  occipitnlis  ;  inion. 

2  Caput ;  cephale  ;  poll.  5  Regio  temporalis  ;  crotaphus. 

3  Sinciput ;  front ;  irons  :  brow. 


184  THE   MUSCULAR   SYSTEM. 

The  Face,1  formed  by  the  forehead  above,  bounded  by  the  base  of  the 
lower  jaw  below,  and  the  ear  on  each  side,  presents  to  us  in  succession 
beneath  the  glabella :  the  root  of  the  nose,  which  is  its  origin  from  the 
forehead ;  the  bridge  or  back  of  the  nose  ;2  the  column  of  the  nose,3 
which  separates  the  nostrils  or  anterior  nares ;  the  labial  groove*  of  the 
upper  lip ;  and  the  labio-mental  groove,5  between  the  lower  lip  and  the 
chin.  From  the  bridge  slope  off  the  sides  of  the  nose,  connected  below 
with  the  dilated  wings,  which  bound  the  nostrils  externally.  The  fissure 
of  the  mouth  is  terminated  on  each  side  by  the  conjunction  of  the  lips, 
named  the  angles  of  the  mouth  or  oral  angles,6  The  upper  lip  is 
denned  on  each  side  by  the  naso-labial  furrow,7  which  becomes  more 
marked  with  the  advance  of  age.  Below  the  eyebrows  are  the  eyelids, 
separated  by  the  pal'pebral  fissure,  the  extremities  of  which  are  the 
angles  or  canthi  of  the  eye,  or  of  the  orbit.  The  cheeks  are  bounded 
by  the  zygoma,  the  ear,  the  angle  and  base  of  the  lower  jaw,  the  chin, 
lips,  and  nose.  The  space  in  the  vicinity  of  the  ear  extending  to  the 
angle  of  the  jaw  and  the  sterno-mastoid  prominence  of  the  neck,  is  the 
parotid  region, 

The  scalp8  or  skin  of  the  vault  of  the  cranium  where  covered  with 
hair,  is  thick,  dense,  and  inextensible ;  and  its  deeper  part  is  filled 
with  hair  follicles,  sweat  glands,  and  sebaceous  glands,  associated  with 
adipose  tissue.  On  the  forehead  and  temples  it  is  thinnest  and  most 
extensible.  The  hairs  of  the  scalp  diverge  in  whorls  from  a  central 
point  at  the  top  of  the  head,  called  the  crown  or  vertex,9  The  scalp 
tightly  adheres  by  short  connective  tissue  to  the  occipito-frontal  muscles, 
and  follows  all  their  movements ;  but  the  skin  alone  of  the  forehead  is 
thrown  into  transverse  wrinkles  by  the  contraction  of  their  frontal  bel- 
lies. The  skin  of  the  eyebrows  is  thick  and  dense,  and  is  moved  with 
that  of  the  forehead.  The  skin  of  the  eyelids  is  thin,  and  the  con- 
nective tissue  attaching  it  to  the  orbicular  muscle  beneath  is  devoid 
of  fat.  In  injuries  about  the  entrance  of  the  orbit,  blood  readily 
pervades  this  connective  tissue,  giving  rise  to  what  is  commonly  called 
"black  eye."  The  skin  of  the  nose  is  thin  and  movable  above,  but  is 
thicker,  more  dense,  and  intimately  connected  with  the  subjacent  part 
below,  in  which  position  it  is  filled  with  large  sebaceous  glands.  The  skin 

1  Facies ;  vultus  ;  prosopon.  5  Sulcus  mento-labialis. 

2  Dorsum  nasi.  6  Commissures  of  the  mouth. 

3  Columna  nasi.  7  Sulcus  naso-labialis. 

4  Philtrum  ;  amatorium  ;  amabile  ;  sul-  8  Capillitium. 
cus,  or  lacuna  labii  superioris.  9  Spondylus. 


THE  MUSCULAR  SYSTEM.  185 

of  the  lips,  where  furnished  with  large  hairs,  is  thick ;  but  at  the  borders  is 
very  thin  and  closely  adherent  to  the  orbicular  muscle.  The  skin  of  the 
chin  is  thick,  filled  with  hair  follicles,  sebaceous  and  sweat  glands,  and 
is  most  intimately  blended  with  the  muscles  beneath.  The  skin  of  the 
cheeks  is  thin,  and  closely  associated  with  a  thick  subcutaneous  adipose 
layer  involving  several  of  the  muscles ;  and  in  the  interval  of  the  masseter 
and  buccinator  muscles,  the  cheek  is  occupied  with  a  large  mass  of  soft 
fat  tissue.  The  skin  at  the  back  part  of  the  cheek  is  like  that  of  the 
chin,  though  less  dense,  and  is  not  blended  with  the  contiguous  muscles. 


FASCIA  OF  THE  HEAD. 

Fasciae  readily  separated  from  the  contiguous  parts  as  distinct  layers, 
on  the  head  are  found  only  in  the  temporal  region.  In  other  positions 
they  are  represented  by  the  thin  and  closely  adherent  investments  of  the 
muscles  of  the  scalp  and  face,  and  by  the  subcutaneous  adipose  layer. 

The  Superficial  temporal  fascia1  is  a  thin  but  distinct  layer  of  loose 
fibrous  tissue  beneath  the  skin  of  the  temple.  It  is  attached  above  to 
the  aponeurosis  of  the  occipito-frontal  muscle,  and  is  continuous  with 
the  thin  layers  of  connective  tissue  investing  the  fleshy  bellies  of  the 
latter  and  the  palpebral  orbicular  muscle.  It  incloses  the  auricular 
muscles  and  the  superficial  temporal  blood-vessels. 

The  Deep  temporal  fascia2  is  a  strong,  bluish-white  and  shining 
fibrous  membrane  extended  between  the  curved  boundary  of  the  tem- 
poral fossa  and  the  zygoma.  Its  lower  part  is  divided  into  two  layers, 
between  which  is  some  loose  areolar  tissue  and  more  or  less  fat.  The 
inner  surface  of  the  fascia  affords  a  point  of  origin  to  the  temporal 
muscle. 

MUSCLES  OF  THE  SCALP. 

The  Occip'ito-front'al  mus'cle3  extends  from  the  occiput  to  the  fore- 
head, and  consists  of  two  fleshy  bellies  connected  by  an  intermediate 
aponeurosis. 

The  occipital  belly,4  shorter  and  narrower  than  the  other,  arises  from 
the  superior  semicircular  ridge  of  the  occipital  bone,  and  ascends  in  an 
inward  direction  to  its  aponeurosis. 

1  Fascia  temporalis  superficial.  3  M.  occipito  frontalis;  m.  epicranius  ; 

2  Fascia  temporalis  profunda;  f.  tern-       m.  digastricus  cranii. 
poralis  ;  temporal  aponeurosis.  4  M.  occipitalis. 


186 


THE   MUSCULAR   SYSTEM. 


The  frontal  belly,1  paler  than  the  former,  arises  from  the  internal  angular 
FlG  147  process  and   superciliary 

ridge  of  the  frontal  bone, 
and  ascends  to  its  apo- 
neurosis.  A  prolongation 
from  this  belly,  at  the 
root  of  the  nose  to  the 
nasal  compressor  mus- 
cle, is  usually  described 
as  distinct,  under  the  name 
of  the  nasal  pyramidal 
muscle.2 

The  occipito-frontal 
aponeurosis3  is  a  thin  sheet 
of  tendinous  fibres  cover- 
ing the  upper  part  of  the 
head  continuously  from 
side  to  side.  Between  the 
occipital  bellies  of  the 
two  muscles  it  is  attached 
to  the  occipital  protuber- 
ance, and  in  the  vicinity 
of  the  temporal  ridge  on 
each  side  is  blended  with 
the  superficial  temporal 
fascia.  It  is  loosely  at- 
tached to  the  periosteum 
beneath,  but  is  closely  ad- 
herent to  the  integument 
above,  so  that  in  the  ac- 
tion of  its  muscular  bellies 
the  scalp  is  moved  back- 
ward and  forward  on  the 
cranium. 


MUSCLES  OF  THE  HEAD  AND  NECK.  1,  2,  occipito-frontal  muscle : 
1,  its  frontal  belly;  2,  its  occipital  belly;  3,  nasal  pyramidal  mus- 
cle; 4,  superior,  and  5,  posterior  auricular  muscles;  7,  labio-nasal 
elevator;  8,  elevator  of  the  upper  lip;  9,  nasal  compressor ;  10, 11, 
zygomatic  muscles ;  12,  masseter  muscle ;  13,  buccinator ;  14,  de- 
pressor of  the  oral  angle ;  15,  oral  orbicular  muscle ;  16,  elevator 
of  the  oral  angle ;  17, 18,  depressor  of  the  lower  lip ;  T£,  sterno- 
mastoid*  muscle;  20,  trapezius;  21,  posterior  belly  of  the  digastric 
and  the  sty lo-hyoid  muscle ;  22,  anterior  belly  of  the  former ;  23, 
loop  of  fibrous  tissue  attaching  the  tendon  of  the  digastric  mus- 
cle to  the  hyoid  bone;  24,  omo-hyoid  muscle;  25,  sterno-hyoid; 
26,  sterno-thyroid,  seen  to  the  outer  side  and  behind  the  anterior 
belly  of  the  omo-hyoid;  27,  mylo-hyoid;  28,  splenius;  29,  elevator 
of  the  scapular  angle;  30,  31,  middle  and  anterior  scalene  mus- 
cles ;  32,  clavicle. 


1  M.  frontalis. 

2  M.  pyramidalis  nasi ;  m.  nasum  dila- 
tans ;   m.   processus   nasi ;    fronto-nasal 
muscle. 


3  Epicranial  aponeurosis  ;  membrana 
epicrania ;  galea  capitis ;  galea  aponeu- 
rotica  capitis ;  g.  tendinea  Saritorini. 


THE   MUSCULAR   SYSTEM.  187 


MUSCLES  OF  THE  EYELIDS  AND  EYEBROWS. 

The  Pal'pebral  Orbic'ular  muscle1  forms  a  thin  elliptical  layer  sur- 
rounding the  entrance  of  the  orbit,  immediately  beneath  the  skin.  It 
arises  from  the  internal  angular  process  of  the  frontal  bone,  the  nasal 
process  of  the  superior  maxillary  bone,  and  the  internal  palpebral  liga- 
ment. From  this  origin  the  muscle  proceeds  outwardly  in  the  upper  eye- 
lid and  the  eyebrow,  and  returns  below  the  palpebral  fissure  to  be  inserted 
into  the  same  points  from  which  it  started.  The  portion  corresponding 
with  the  eyelids  is  thinner  and  paler  than  elsewhere,  and  has  been 
described  as  distinct  under  the  name  of  the  ciliary  muscle.2  A  fasci- 
culus or  offset,  springing  from  the  back  part  of  the  lachrymal  bone  and 
passing  upon  the  eyelids  along  the  course  of  the  lachrymal  canals,  was 
particularly  described,  by  the  late  Professor  Horner,  under  the  name  of 
the  tar'sal  ten/sor.3 

The  palpebral  orbicular  muscle  closes  the  eyelids  and  draws  the  skin 
in  a  radiating  manner  toward  the  inner  angle.  The  ciliary  portion  is 
constantly  engaged  in  the  act  of  winking. 

The  Pal'pebral  Ele'vator  muscle4  is  contained  within  the  orbit.  It 
arises  above  the  optic  foramen,  and  passes  forward  beneath  the  roof  of 
the  orbit ;  expanding  in  its  course,  and  terminating  in  a  broad,  thin  ten- 
don, it  is  inserted  into  the  edge  of  the  superior  palpebral  cartilage.  As 
indicated  by  the  name,  the  muscle  raises  the  upper  eyelid. 

The  Superciliary  muscle5  arises  from  the  inner  extremity  of  the  super- 
ciliary ridge,  and  proceeds  outwardly  and  a  little  upward  to  become 
blended  with  the  palpebral  orbicular  and  occipito-frontal  muscles,  between 
which  and  the  bone  it  is  situated. 

The  muscles  of  the  two  sides  throw  the  skin  at  the  middle  of  the  fore- 
head into  vertical  wrinkles,  as  in  frowning. 

1  M.  orbicularis   palpebrarum;    m.  o.  4  M.  levator  palpebrge  superioris;  pal- 
oculi ;  m.  pal.  ciliaris  ;  m.  palpebralis  ;  pebrse  superioris  primus ;  apericus  pal- 
m.  naso-palpebralis ;  m.  maxillo-palpe-  pebrarum  rectus  ;  seclusor  palpebrarum; 
bralis  ;  m.  orbicularis  latus  ;  palpebra-  apertor  oculi ;  orbito-palpebral  muscle, 
rum  duo  musculi ;  sphincter,  or  constric-  5  M.  superciliaris  ;    m.  supercilii ;    m. 
tor  palpebrarum,  or  oculi.  corrugator  supercilii ;  m.  c.  frontis ;  m. 

2  M.  ciliaris.  c.  Coiterii ;   m.  cutaneo-  or  fronto-super- 

3  M.  tensor  tarsi ;  m.  Horneri;  m.  sacci  ciliaris;  m.  frontalis  verus. 
lachrymalis. 


188  THE   MUSCULAR   SYSTEM. 

MUSCLES  OF  THE  EYEBALL. 

See  the  Account  of  the  Eye. 

MUSCLES  OF  THE  EAR. 
See  the  Account  of  the  Ear. 

MUSCLES  OF  THE  NOSE. 

The  Na'sal  Compressor1  is  a  thin,  triangular  muscle  arising  from  the 
fore  part  of  the  superior  maxillary  bone  and  diverging  upon  the  side  of 
the  nose.  On  the  back  of  the  latter  it  terminates  in  a  thin  aponeurosis, 
which  conjoins  that  of  the  opposite  side,  is  attached  to  the  tip  of  the 
nose,  and  is  connected  with  a  pair  of  fleshy  slips2  from  the  occipito-frontal 
muscles. 

The  Na'sal  Dila'tor3  consists  of  short,  indistinct  muscular  fibres,  situ- 
ated between  the  cartilages  of  the  wing  of  the  nose  and  the  skin,  with 
which  they  are  intimately  blended. 

MUSCLES  OF  THE  LIPS  AND  CHEEK. 

The  O'ral  Orbic'ular  muscle4  is  an  elliptical  fasciculus  of  fibres  sur- 
rounding the  mouth,  and  blended  with  all  the  muscles  which  converge  to 
it.  At  the  angles  of  the  mouth  its  fibres,  except  the  most  superficial 
ones,  decussate  with  those  of  the  buccinators,  and  with  the  elevators  and 
depressors  of  the  oral  angles. 

This  muscle  is  a  sphincter,  and  antagonizes  all  the  other  muscles  of 
the  mouth.  When  closely  contracted,  it  projects  the  lips  as  in  the  acts 
of  kissing  and  sucking. 

The  LaVio-na'sal  el'evator5  arises  from  the  nasal  process  of  the  supe- 

1  M.  compressor  naris ;    m.  transver-  4  M.  orbicularis  oris ;     m.  constrictor 
sails  nasi ;  m.  triangularis  nasi ;  m.  na-  oris ;  m.  sphincter  labiorum  ;  m.  oscula- 
salis ;  m.  rinalus  ;   m.  myrtiformis ;    m.  torius ;  m.  basiator ;  m.  labialis ;  m.  semi- 
constrictor  naris ;  in.  dilatator  alae  nasi.  or  demi- orbicularis  ;  m.  supra-semi-or- 

2  Nasal  pyramidal  muscles.  bicularis. 

3  M.  levator  proprius  alse  nasi  anterior  5  M.  levator  labii  superioris   alaeque 
et  posterior ;  m.  dilatator  naris  ant.  et  nasi ;  elevator  of  the  upper  lip  and  wing 
post. ;  m.  pinnse  dilatator.  of  the  nose ;    m.   incisiyus  lateralis  et 

pyramidalis. 


THE   MUSCULAR   SYSTEM.  189 

rior  maxillary  bone,  and  as  it  descends  separates  into  two  fasciculi,  of 
which  one  is  inserted  into  the  wing  of  the  nose,  while  the  other  is  pro- 
longed to  the  upper  lip,  where  it  is  blended  with  the  contiguous  muscles. 

The  La'bio-na'sal  depress'or1  is  a  small  muscular  slip  situated  just 
exterior  to  the  mucous  membrane  of  the  upper  lip  at  the  side  of  the 
fraenum.  It  arises  from  the  point  of  the  incisive  alveoli  of  the  superior 
maxillary  bone,  and  ascends  to  be  inserted  into  the  wing  and  column  of 
the  nose  and  become  blended  with  the  upper  margin  of  the  oral  orbicular 
muscle. 

The  El'evator  of  the  Upper  Lip2  arises  from  the  malar  and  superior 
maxillary  bones  just  above  the  infra-orbital  foramen,  and  descends  to 
become  blended  with  the  contiguous  muscles  of  the  upper  lip. 

The  El'evator  of  the  O'ral  Angle3  is  partially  concealed  by  the  pre- 
ceding muscle.  It  arises  from  the  superior  maxillary  bone  below  the 
infra-orbital  foramen,  and  descends  in  a  convergent  manner  to  the  angle 
of  the  mouth.  Between  it  and  the  elevator  of  the  upper  lip  are  the 
infra-orbital  nerve  and  artery. 

The  Zygomat'ic  muscles  are  two  narrow  fasciculi  extending  obliquely 
from  the  most  prominent  part  of  the  cheek  to  the  angle  of  the  mouth. 

The  Larger  Zygomat'ic  muscle,4  external  to  the  smaller  one,  arises 
from  the  zygomatic  process  of  the  malar  bone,  and,  after  reaching  the 
angle  of  the  mouth,  becomes  blended  with  the  contiguous  muscles. 

The  Smaller  Zygomat'ic  muscle5  is  inconstant  in  size  and  exact 
position,  and  occasionally  is  absent.  It  arises  from  the  malar  bone,  and 
terminates  near  the  angle  of  the  mouth  by  blending  with  the  elevator  of 
the  upper  lip. 

The  zygomatic  muscles  elevate  the  angles  of  the  mouth  outwardly,  as 
in  smiling. 

The  Depress'or  of  the  Lower  Lip,6  a  square  muscle  situated  at  the 


1  M.  depressor  labii  superioris  alaeque  abducens  labiorum ;  m.  elevator  labio- 
nasi ;  depressor  of  the  upper  lip  and  of  rum  communis. 

the  wing  of  the  nose  ;  m.  depressor  alee  4  M.  zygomaticus  major ;  m.  distorter 

nasi ;  m.  myrtiformis.  oris  ;  zygomato-labial  muscle. 

2  M.  levator  labii  superioris ;    m.  in-  5  M.  zygomaticus  minor ;  small  zygo- 
cisivus.  mato-labial  muscle. 

3  M.  levator  anguli  oris;   elevator  of  6M.  depressor  labii  inferioris;  m.quad- 
the  angle  of  the  mouth ;  m.  caninus ;  m.  ratis  menti ;  m.  mento-labialis. 


190  THE   MUSCULAR  SYSTEM. 

side  of  the  chin,  arises  from  the  base  of  the  lower  jaw  and  ascends  in- 
wardly to  be  inserted  into  the  lower  lip. 

The  El'evator  of  the  Lower  Lip1  is  a  small  square  muscle  situated 
just  exterior  to  the  mucous  membrane  of  the  lower  lip  at  the  side  of  the 
frasnum.  It  arises  from  the  front  of  the  outer  incisive  and  canine  alveoli 
of  the  lower  jaw,  and  descends  inwardly  to  be  inserted  into  the  lower  lip. 

The  Depress'or  of  the  O'ral  Angle2  is  a  triangular  muscle,  which  arises 
from  the  base  of  the  lower  jaw  at  the  side  of  the  chin,  and  is  inserted  by 
its  apex  into  the  angle  of  the  mouth,  where  it  blends  with  the  contiguous 
muscles. 

The  Buccina'tor  muscle3  contributes  to  the  formation  of  the  cheek. 
It  arises  from  the  pterygo-rnaxillary  ligament  and  from  the  alveolar 
border  of  both  jaws  as  far  forward  as  the  first  molar  tooth.  From  these 
points  the  fibres  proceed  forward  and  converge  to  the  angle  of  the  mouth, 
where  they  cross  one  another  and  become  confluent  with  the  oral  orbicu- 
lar muscle. 

Internally  it  is  in  contact  with  the  mucous  membrane  of  the  mouth,  and 
externally  is  closely  invested  with  a  thin  fascia.  Its  back  part  is  sepa- 
rated from  the  ramus  of  the  lower  jaw  by  means  of  a  mass  of  fat,  re- 
markable for  its  softness  and  slight  attachment  to  the  contiguous  struct- 
ures. The  disappearance  of  this  fat  in  emaciation  gives  rise  to  the 
hollow  cheek.  Opposite  the  second  molar  tooth  of  the  upper  jaw  the 
buccinator  is  perforated  by  the  termination  of  the  parotid  duct. 

When  the  buccinators  alone  contract,  they  widen  the  mouth ;  but  if  they 
contract  in  conjunction  with  the  oral  orbicular  muscle,  they  press  the 
cheeks  close  to  the  jaws ;  or  if  the  mouth  is  filled  with  air,  this  is  com- 
pressed, as  in  the  acts  of  blowing  and  whistling. 

The  Pter'ygo-max'illary  lig'ament  is  a  fibrous  band,  extended  be- 
tween the  external  pterygoid  process  of  the  sphenoid  bone  and  the  pos- 
terior end  of  the  molar  ridge  of  the  lower  jaw,  serving  as  a  common 
origin  to  the  buccinator  muscle  and  the  superior  constrictor  of  the 
pharynx. 

1  M.  levator  labii  inferior-is ;  m.  levator      laris  oris ;    m.  maxillo-labialis ;  m.  de- 
menti; m.  incisivus  inferior;  m.  penicil-      pressor  labiorum  communis. 

latus ;  mento-labial  muscle.  3  M.  retractor  anguli  oris ;  m.  bucco- 

2  M.  depressor  anguli  oris ;  depressor      alveolo-maxillaris  ;    m.  alveolo-labialis ; 
of  the  angle  of  the  mouth ;  m.  triangu-      m.  mansorius. 


THE   MUSCULAR  SYSTEM. 


191 


THE  MUSCLES  OF  THE  LOWER  JAW,  OR  OF  MASTICATION. 

The  Mass'eter  muscle,1  thick  and  oblong  square,  is  situated  at  the 
back  of  the  cheek,  and  extended  between  the  zygoma  and  angle  of  the 
lower  jaw.  It  has  a  number  of  tendinous  bands  interspersed  with  its 
structure,  and  is  separable  into  two  portions,  the  fibres  of  which  pursue 
a  different  course. 

The  superficial  and  larger  portion  of  the  muscle  arises  tendinously 
from  the  upper  maxillary  bone  and  the  lower  margin  of  the  malar  bone, 
and  descends  backward  to  be  in-  FlG  143. 

serted  into  the  lower  half  of  the 
ramus  and  angle  of  the  lower  jaw. 
The  deeper  portion  arises  from  the 
zygomatic  process  of  the  temporal 
bone,  and  descends  a  little  forward 
to  be  inserted  into  the  upper  half 
of  the  ramus  of  the  lower  jaw. 


The  External  Ptery'goid  muscle2 
is  short,  thick,  and  triangular,  and 
occupies  the  upper  part  of  the 
spheno-maxillary  fossa.  It  arises 
from  the  under  surface  of  the  great 
wing  and  the  outer  surface  of  the 
external  pterygoid  process  of  the 
sphenoid  bone,  and  converges  to 
be  inserted,  by  means  of  a  short, 
thick  tendon,  into  the  depressed  sur- 
face of  the  front  of  the  neck  of  the 
lower  jaw. 

Externally  this  muscle  is  crossed 
by  the  internal  maxillary  artery  and  the  tendon  of  the  temporal  muscle ; 
and  internally  it  is  in  contact  with  the  internal  pterygoid  muscle  and  the 
inferior  maxillary  nerve. 

The  Internal  Pter'ygoid  muscle3  is  square  and  thick,  and  is  situated 
within  the  position  of  the  ramus  of  the  jaw.     It  arises  from  the  ptery- 

1  M.  mandibularis ;  m.  zygomato-max-  3  M.  pterygoideus  interims,  or  major; 
illaris.  m.  masseter  interims ;  m.  latens  in  ore ; 

2  M.  pterygoideus  externus,  or  minor;  m.  pterygo-anguli-maxillaris ;  m.  ptery- 
m.  pterygo-colli-maxillaris ;  m.  pterygo-  go-maxillaris  majus ;   m.  alaris,  or  ali- 
maxillaris  minus;  m.  alaris,  or  aliformis  formis  major. 

minor. 


VIEW  OF  THE  INTERIOR  PART  OF  THE  LEFT  SIDE  OF 

THE  FACE.  1,  condyle  of  the  lower  jaw ;  2,  angle  of 
the  jaw ;  3,  base ;  4,  symphysis ;  5,  sub-maxillary 
fossa;  6,  attachment  of  the  mylo-hyoid  muscle  to 
the  corresponding  ridge;  7,  origin  of  the  genio- 
hyoid  muscles;  8,  origin  of  the  genio-glossal 
muscles;  9,  masseter  muscle;  10,  internal  ptery- 
goid muscle ;  11,  external  pterygoid  muscle. 


192 


THE   MUSCULAR   SYSTEM. 


gold  fossa,  and  descends  outward  and  backward  to  be  inserted  into  the 
inner  surface  of  the  ramus  and  angle  of  the  lower  jaw. 

The  Tem/poral  muscle1  occupies  the  temporal  fossa,  and  is  covered  by 
the  temporal  fascia.  It  arises  from  the  entire  surface  of  the  former  and 
from  the  upper  part  of  the  latter,  and  converges  to  an  interior  tendinous 
layer,  which  becomes  a  thick,  flattened  fasciculus,  descending  to  be  in- 
serted into  the  inner  surface  and  anterior  border  of  the  coronoid  process 
of  the  lower  jaw. 

The  temporal,  masseter,  and  pterygoid  muscles  are  the  active  agents 
in  mastication.  The  movements  produced  are  those  of  elevation  of 
the  lower  jaw,  together  with  a  lateral,  forward  and  backward  motion. 
The  elevation  of  the  lower  jaw,  productive  of  firm  'pressure  of  the 
lower  against  the  upper  teeth,  is  the  result  of  the  contraction  of  the  tem- 
poral muscles  and  the  internal  portions  of  the  masseters.  Depression 
of  the  lower  jaw  occurs  by  its  weight  alone,  though  aided  by  the  digas- 
tric and  other  muscles  extended  between  it  and  the  hyoid  bone,  when 
this  is  fixed  in  its  position.  The  grinding  movement  of  the  lower  jaw  is 
performed  by  the  pterygoid,  masseter,  and  temporal  muscles.  The  external 

FIG.  149. 


VIEW  OF  THE  TEMPORAL  MUSCLE.     The  temporal  fascia  and  zygoma  removed. 

pterygoid  muscles  and  the  external  portions  of  the  masseter  muscles 
draw  the  jaw  forward ;  the  temporal  muscles  and  internal  portions  of 
the  masseters  draw  it  back  again ;  and  the  internal  pterygoid  muscles, 
contracting  alternately,  draw  the  jaw  to  either  side. 

1  M.  temporalis ;  m.  crotaphites ;  m.  arcadi-temporo-maxillaris ;  m.  temporo  max- 
illaris. 


THE   MUSCULAR   SYSTEM.  1Q3 


THE   NECK. 

The  Neck,1  which  forms  the  short  cylindrical  column  connecting  the 
head  with  the  thorax,  varies  in  length  and  thickness  in  different  individ- 
uals of  the  same  age  and  sex.  Its  bony  axis  is  situated  more  posteriorly 
than  anteriorly,  in  consequence  of  which  the  head  is  disposed  to  fall  for- 
ward. 

The  front  of  the  neck,  or  the  throat,2  presents  a  prominence  in  the 
adult  male,  commonly  called  "Adam's  apple."3  This  is  produced  by 
the  larynx,  which,  from  its  less  degree  of  development  before  puberty, 
and  at  all  periods  of  life  in  the  female,  is  not  evident  externally. 

The  elevation  on  each  sidq  of  the  neck,  descending  from  behind  the 
position  of  the  ear  to  the  sternum,  is  produced  by  the  sterno-mastoid 
muscles.  The  concavity  between  the  latter  just  above  the  breast  is  the 
ju/gular  fossa;4  and  the  shallower  depression  outside  of  the  muscle 
above  the  clavicle  is  the  supra-clavic'ular  fossa.5 

The  skin  of  the  neck  is  thin  and  movable,  and  is  readily  elevated  into 
folds.  The  two  conspicuous  folds,  observed  in  old  people,  descending 
from  the  sides  of  the  chin  toward  the  lower  part  of  the  neck,  are  pro- 
duced upon  the  anterior  borders  of  the  subcutaneous  cervical  muscles, 
which  become  extended  through  elevation  of  the  lower  jaw  consequent 
on  the  loss  of  the  teeth  and  their  alveoli  in  both  jaws.  Beneath  the 
muscles  just  mentioned  is  the  cervical  fascia,  which  incloses  the  sterno- 
mastoid  muscles. 

The  middle  of  the  neck  in  front  of  the  vertebra  is  occupied  by  the 
pharynx  and  oesophagus,  the  root  of  the  tongue,  the  hyoid  bone,  the 
larynx  and  trachea,  and  the  thyroid  body.  At  the  sides  of  these  parts 
the  principal  cervical  blood-vessels  and  nerves  are  situated,  enveloped  in 
the  deep  cervical  fascia. 

MUSCLES  AND  FASCLE  OF  THE  NECK. 

THE  SUBCUTANEOUS  CERVICAL  MUSCLE. 

The  Subcuta'neous  Cer'vical  muscle6  is  a  broad,  thin,  and  pale  lam- 
ina arising  in  the  connective  tissue  covering  the  upper  part  of  the  del- 
toid and  pectoral  muscles.  Passing  over  the  clavicle,  it  ascends  the 


1  Collum  ;  cervix ;  trachelos ;  anchen.  5  Fovea  supra-clavicularis. 

-Guttur;  jugulum.  «  M.  s.  cervicis,  or  colli;  m.  platysm.-i 

3  Pornum  Adami;  eminentia  thyroid ea;       myoides  ;    m.    cutaneus  ;    in.   latissimus 
nodus  gutturis.  colli;  m.  peaucier. 

4  Fossa  jngularis. 

13 


194 


THE   MUSCULAR  SYSTEM. 


neck  inwardly  to  the  lower  jaw,  where  its  most  anterior  fibres  join  those 
of  the  opposite  muscle,  while  others  are  inserted  into  the  side  of  the 
chin,  and  become  blended  with  the  depressors  of  the  lower  lip  and  oral 
angle,  and  the  most  posterior  ones  terminate  in  the  fascia  investing  the 
masseter  muscle  and  parotid  gland.  A  small  offset1  crosses  the  cheek 
transversely  from  over  the  masseter  muscle  to  the  vicinity  of  the  angle 
of  the  mouth. 

This  muscle  will  aid  the  depression  of  the  lower  jaw ;  Jbut  its  main 
purpose  appears  to  be  to  extend  the  skin  of  the  neck  between  the  cla- 
vicle and  lower  jaw,  thus  elevating  it  from  the  influence  of  exterior  pres- 
sure upon  the  air-passages  and  blood-vessels. 


FIG.  150. 


THE  CERVICAL  FASCIA. 

Upon  removing  the  subcutaneous  cervical  muscle,  the  Cer'vical  fas'cia2 
is  exposed  to  view.  Its  upper  part  forms  a  sheath  for  the  parotid  and 
submaxillary  glands,  which  are  separated  from  each  other  by  a  well- 
marked  process  of  the  fascia,  called  the  sty'lo-max'illary  lig'ament,3 
which  extends  from  the  styloid  process  of  the  temporal  bone  to  the  angle 

of  the  lower  jaw,  and  inwardly  to 
the  sheath  of  the  principal  cervical 
blood-vessels.  In  advance  of  the 
parotid  gland,  the  fascia  invests 
the  masseter  muscle  and  adheres 
along  the  base  of  the  lower  jaw. 
At  the  lower  part  of  the  neck  the 
fascia  adheres  along  the  upper  bor- 
der of  the  sternum  and  clavicle,  and 
is  continuous  in  front  of  these  bones 
with  the  thoracic  fascia.  Behind 
the  neck,  it  is  continuous  with  the 
layer  inclosing  the  trapezius  mus- 
cle ;  and  in  proceeding  forward  it 

incloses  the  sterno-mastoid  muscle,  and  the  elevators  and  depressors  of 
the  hyoid  bone  and  larynx.  Processes  of  the  fascia,  continued  inwardly, 
inclose  the  trachea  and  larynx,  the  oasophagus  and  pharynx ;  form  the 
sheath  of  the  large  cervical  blood-vessels,  and  become  continuous  with 
the  fibrous  investment  of  the  muscles  in  front  of  the  cervical  vertebras. 


INNER  PART  OF  THE  EAMUS  OF  THE  LOWER  JAW,  right 
side.  1,  temporal  bone ;  2,  lower  jaw ;  3,  capsular 
ligament  of  the  articulation  of  the  latter ;  4.  spheno- 
maxillary  ligament;  5,  entrance  of  the  inferior 
dental  canal ;  6,  stylo-maxillary  ligament. 


1  M.  risorius  Santorini. 

2  Fascia  cervicalis;  fascia  colli;  fascia  superficialis  et  profunda  cervicis;  super- 
ficial and  deep  or  proper  cervical  fascia. 

3  Ligamentum  stylo-maxillare. 


THE   MUSCULAR   SYSTEM. 


195 


Another  process,  separating  the  pterygoid  muscles,  and  extended  from 
the  spinous  process  of  the  sphenoid  bone  to  the  lower  jaw  at  the  inner 
border  of  the  dental  foramen,  constitutes  the  sphe'no-max'illary  lig'a- 
ment,1 

THE  STERNO-MASTOID  MUSCLE. 


; 


The    Ster'no-mas'toid  FIG.  151. 

muscle2  is  the  largest  and 
most  conspicuous  of  the 
muscles  of  the  neck.  It 
arises  by  a  flat  tendon 
from  the  upper  fore  part 
of  the  sternum,  and  ten- 
dinous and  fleshy  from  the 
inner  third  of  the  clavicle. 
The  two  portions  are  sep- 
arated at  their  origin  by  an 
angular  interval,  but  as  the 
clavicular  portion  ascends 
nearly  vertically,  while  the 
sternal  portion  inclines 
backward  in  its  ascent, 
the  two  conjoin  about  the 
middle  of  the  neck  and 
form  a  single  thick  rounded 
belly,  which  proceeds  to  be 
inserted  into  the  mastoid 
process  and  the  superior 
semicircular  line  of  the  occipital  bone. 

When  the  muscles  of  the  two  sides  act  together,  the  head  is  drawn 
downward;  but  when  one  alone  contracts,  the  face  is  directed  toward  the 
opposite  side.  #***  UA&  i&  fe  feu^  I 

DEPRESSORS  OF  THE  HYOID  BONE  AND  LARYNX. 

The  Ster'no-hy'oid  muscle3  is  a  flat  band  arising  from  the  inner  sur- 
face of  the  upper  part  of  the  sternum  and  the  contiguous  portion  of  the 


FRONT  VIEW  OF  THB  MUSCLES  OF  THE  NECK.  1,  posterior,  and 
2,  anterior  belly  of  the  digastric ;  3,  its  intermediate  tendon  at- 
tached to  the  hyoid  bone  and  passing  through  the  insertion  of  the 
Btylo-hyoid  muscle,  4 ;  5,  mylo-hyoid ;  6,  genio-hyoid ;  7,  genio- 
glossal  muscle  of  the  tongue ;  8,  hyo-glossal ;  9,  stylo-glossal ;  10, 
stylo-pharyngeal  muscle ;  11,  sterno-mastoid  muscle ;  12,  its  ster- 
nal origin;  13,  its  clavicular  origin;  14,  sterno-hyoid ;  15,  sterno- 
thyroid ;  16,  thyro-hyoid ;  17,  18,  omo-hyoid  muscle ;  19,  trape- 
zius ;  20,  anterior  scalene  muscle ;  21,  middle  scalene  muscle. 


1  Erroneously  described  under  the  name 
of  internal  lateral  ligament  of  the  articu- 
lation of  the  lower  jaw. 

2  M.  sterno-mastoideus ;     m.    sterno- 


cleido-mastoideus ;  m.  cleido-mastoideus; 
m.  mastoideus  ;  m.  metator  capitis. 

3  M.  sterno-hyoideus ;    m.  sterno-clei- 
do-hyoideus  ;  m.  hyoides  primus. 


196  THE   MUSCULAR  SYSTEM. 

clavicle.    Ascending  the  neck  inwardly,  it  is  inserted  into  the  lower  bor- 
der of  the  body  of  the  hyoid  bone. 

The  Ster'no-thy'roid  muscle,1  broader  than  the  preceding,  arises  from 
the  inner  surface  of  the  upper  part  of  the  sternum,  and  ascends  the  neck 
between  the  former  muscle  and  the  trachea,  to  be  inserted  into  the  oblique 
line  at  the  side  of  the  thyroid  cartilage. 

The  Thy'ro-hy'oid  muscle,2  apparently  a  continuation  of  the  muscle 
just  described,  arises  from  the  oblique  line  of  the  thyroid  cartilage,  and 
ascends  to  be  inserted  into  the  lower  border  of  the  hyoid  bone. 

The  O'mo-hy'oid  muscle3  consists  of  two  fleshy  bellies  united  by  an 
intermediate  tendon.  It  arises  from  the  upper  border  of  the  scapula,  in 
the  vicinity  of  the  coracoid  foramen,  crosses  the  neck  in  an  oblique  man- 
ner beneath  the  sterno-mastoid  muscle,  and  is  inserted  into  the  lower 
margin  of  the  body  of  the  hyoid  bone.  The  two  bellies  of  the  muscle 
in  their  course  form  an  obtuse  angle  with  each  other,  and  this  position 
is  maintained  by  a  connection  of  their  tendon  with  the  cervical  fascia. 

Besides  depressing  the  hyoid  bone  and  larynx,  the  omo-hyoid  muscles 
fix  the  median  position  of  these  parts  in  the  neck. 


ELEVATORS  OF  THE  HYOID  BONE  AND  LARYNX. 

The  Digas'tric  muscle,4  as  indicated  by  the  name,  consists  of  two 
fleshy  bellies  which  are  united  by  an  intermediate  rounded  tendon.  The 
posterior  belly  arises  from  the  digastric  fossa  of  the  temporal  bone,  and 
the  anterior  belly  from  the  inner  surface  of  the  lower  jaw  near  its  sym- 
physis.  Both  descend  to  the  side  of  the  hyoid  bone,  where  their  inter- 
vening tendon  passes  through  the  insertion  of  the  stylo-hyoid  muscle,  and 
is  attached  to  the  former  by  means  of  a  fibrous  band.  A  thin  aponeu- 
rosis,  continuous  with  the  latter,  is  extended  between  the  anterior  bellies 
of  the  two  muscles. 

. 

The  Sty'lo-hy'oid  muscle5  lies  in  contact  with  the  posterior  belly  of  the 
preceding  muscle.  It  arises  from  the  middle  of  the  styloid  process  of 


1  M.  sterno-thyroideus;  m.  bronchius.  4  M.  digastricus;   m.  biventer;   m.  b. 

a  M.  thyro-hyoideus  ;  m.  hyo-thyroi-  maxillae ;  m.  deprimens  maxillae  biven- 

deus.  ter ;  m.  bigaster. 

3  M.  omo-hyoideus  :  m.  coraco-hyoi-  5  M.  stylo  hyoideus;  m.  stylo-hyoides 

deus;  m.  scnpula-liy<  ideus;  m.  hyoidus  major;  m.  stylo-ceratoides;  in.  stylo- 

quartus.  cerato-byoideus. 


THE   MUSCULAR   SYSTEM.  197 

the  temporal  bone,  and  descends  to  be  inserted  into  the  side  of  the  body 
of  the  hyoid  bone,  where  it  is  perforated  by  the  tendon  of  the  digastric 
muscle. 

The  My'lo-hy'oid  muscle1  is  a  triangular  layer,  forming  with  its  fellow 
of  the  opposite  side  the  muscular  floor  of  the  mouth.  It  arises  from 
the  molar  ridge  of  the  lower  jaw,  from  whence  its  fibres  proceed  obliquely 
inward  to  conjoin  with  those  of  the  opposite  muscle,  in  the  median  line, 
extending  from  the  chin  to  the  hyoid  bone. 

The  Geni'o-hy'oid  muscle2  is  a  slender  band  arising  from  the  posterior 
mental  tubercle,  and  descending  in  contact  with  the  corresponding  mus- 
cle of  the  other  side,  to  be  inserted  into  the  body  of  the  hyoid  bone.  It 
is  situated  between  the  inner  part  of  the  nfylo-hyoid  and  the  genio- 
glossal  muscle. 

MUSCLES  OF  THE  TONGUE,  PALATE,  AND  PHARYNX. 

See  the  account  of  these  different  organs. 

MUSCLES  OF  THE  LARYNX. 

See  the  account  of  this  organ. 

DEEP  MUSCLES  OF  THE  FRONT  OF  THE  NECK. 

The  Anterior  Scalene'  muscle3  is  deeply  situated  at  the  lower  part  of 
the  side  of  the  neck.  It  arises  from  the  transverse  processes  of  the 
third  to  the  sixth  cervical  vertebra  inclusively,  and  descends  to  be  in- 
serted into  the  anterior  part  of  the  first  rib. 

In  front  of  the  insertion  of  this  muscle  the  subclavian  vein  passes 
over  the  first  rib. 

The  Middle  Scalene'  muscle4  arises  from  all  the  cervical  transverse 
processes,  usually  excepting  the  fif^t,  and  descends  behind  the  preceding 
muscle  to  be  inserted  into  the  posterior  half  of  the  first  rib. 

Between  the  anterior  and  middle  scalene  muscles  the  axillary  plexus 
of  nerves  and  the  subclavian  artery  take  their  course. 

1  M.  mylo-hyoideus ;  m.  mylo-pharyn-  3  M.  scalenus  aniicus;  m.  s.  prior;  m. 
geus.  costo  trachelius. 

2  M.  genio-hyoideus ;  m.  mento-bicor-  *  M.  scalenus  medius  ;  m.  s.  secundus. 
neus.  / 


198 


THE   MUSCULAR   SYSTEM. 


The  Posterior  Scalene'  muscle,1  small  and  thin,  arises  from  the  two  or 
three  lower  cervical  transverse  processes,  and  descends  to  be  inserted  into 

the  back  part  of  the  second 
FIG.  152.  rib. 

The  scalene  muscles  act- 
ing from  above  elevate  the 
ribs  ;  but  acting  from  be- 
low they  flex  the  neck. 


The  Larger  Straight 
muscle2  arises  by  as  many 
distinct  tendinous  heads, 
from  the  third  to  the  sixth 
cervical  transverse  proc- 
esses inclusively,  and  as- 
cends inwardly  to  be  in- 
serted into  the  basilar 
process  of  the  occipital 
bone. 

The  Smaller  Straight 
muscle3  -arises  from  the 
side  of  the  atlas,  and  as- 
cends inwardly  to  be  in- 
serted into  the  basilar 
process,  beneath  the  last 
muscle. 

The  two  straight  mus- 
cles are  flexors  of  the  head. 


DEEP  MUSCLES  OF  THE  FROXT  OF  THE  NECK.  1,  basilar  process 
of  the  occipital  bone;  2,  mastoid  process;  3,  larger  straight  mus- 
cle; 4,  smaller  straight  muscle;  5,  lateral  straight  muscle;  6,7, 
long  cervical  muscles;  8,  posterior  scalene  muscle;  9,  anterior 
scalene  muscle  ;  10, middle  scalene  muscle;  11, 12,  first  and  second 
ribs;  13,  position  at  which  the  subclavian  artery  and  axillary 
plexus  of  nerves  emerge  over  the  first  rib,  between  the  anterior 
and  middle  scalene  muscles  ;  14,  third  dorsal  vertebra;  15,  atlas; 
i6, 17,  intertransverse  muscles. 


The  Long  Cer'vical  muscle4  extends  along  the  side  of  the  neck,  and 
is  quite  complex  in  its  arrangement.  It  consists  of  two  portions,  of 
which  one  arises  from  the  side  of  the  bodies  of  the  three  upper  dor- 
sal and  the  three  lower  cervical  vertebrae,  and  ascends  to  be  inserted  by 
distinct  tendons  into  the  fourth  and  fj|ya  cervical  transverse  processes,  and 
partially  tendinous  and  fleshy  into  the  bodies  of  the  second,  third,  and 
fourth  cervical  vertebrae.  The  remaining  portion  arises  by  distinct  ten- 


1  M.  scalenus  posticus ;  m.  s.  tertius. 

2  M.  rectus  capitis  anticus  major;  m. 
r.  c.  internus  major;    m.  r.  c.  anterior 
longus  ;  m.  trachelo-basilaris  ;  larger  an- 
terior straight  muscle. 

3  M.  rectus  capitis  anticus  minor ;  m. 


r.  c.  internus  minor;  m.  r.  c.  anterior 
brevis;  m.  trachleo-basilaris  minus;  m. 
rennuens  ;  m.  annuens ;  smaller  anterior 
straight  muscle. 

4  M.  longus  colli ;  m.  pre-dorso-cervi- 
calis ;  m.  pre-dorso-atloideus. 


V 
THE   MUSCULAR   SYSTEM.  199 

dons  from  the  third,  fourth,  and  fifth  cervical  transverse  processes,  and 
ascends  to  conjoin  with  the  preceding  portion  and  to  be  inserted  in  front 
of  the  atlas. 

This  muscle  bends  the  neck  forward. 

TOPOGRAPHICAL  SKETCH  OF  THE   ANATOMY  OF  THE  NECK. 

Upon  removing  the  skin  of  the  neck  and  the  subcutaneous  cervical 
muscle,  the  cervical  fascia  is  exposed,  with, the  external  jugular  vein  de- 
scending from  behind  the  angle  of  the  jaw  to  about  the  middle  of  the 
clavicle,  where  it  dips  inward  to  join  the  subclavian  vein.  Upon  removing 
the  superficial  layer  of  the  cervical  fascia,  the  sterno-mastoid  muscle  is 
seen  pursuing  its  course  from  the  sternum  to  the  mastoid  process,  and 
beneath  it,  crossing  the  neck  in  an  opposite  flfirection,  is  the  omo-hyoid 
muscle.  If  the  line  of  the  latter  be  continued  to 'the  chin,  the  side  of 
the  neck  will  be  divided  by  the  two  muscles  into  four  triangles. 

The  posterior  cer'vical  triangle  is  occupied  with  muscles,  to  be 
described  in  the  account  of  the  back. 

The  anterior  cer'vical  triangle  contains  the  root  of  the  tongue,  the 
hyoid  bone,  larynx  and  trachea,  and,  behind  these,  the  pharynx  and  oeso- 
phagus. The  larynx  and  trachea  are  covered  by  the  depressor  muscles 
of  those  organs ;  and  beneath  them,  on  the  trachea,  is  the  thyroid  gland. 
The  lower  part  of  this  triangle  corresponds  with  the  depression  above  the 
sternum,  called  the  ju/gular  fossa. 

The  inferior  cer'vical  triangle  corresponds  with  the  supra-clavic'ular 
fossa,  The  deeper  layer  of  the  cervical  fascia  being  removed  from  it,  a 
quantity  of  loose  areolar  tissue,  containing  the  supra- clavicular  lymphatic 
glands,  is- exposed.  Upon  removing  the  latter,  the  triangle  will  be  found 
to  extend  into  a  deep  fossa  between  the  clavicle  and  first  rib,  and  con- 
tinuous outwardly  with  the  axilla.  The  extent  of  the  fossa  varies  with 
the  position  of  the  shoulder.  If  this  is  elevated  and  thrown  back,  the 
fossa  is  deepened  and  narrowed ;  if  depressed:-  and  thrown  forward,  the 
fossa  is  rendered  shallower  and  broader,  and  its  parts  become  more  dis- 
tinctly visible.  Crossing  the  loirar  part  of  the  triangle  are  the  supra- 
scapular  and  transverse  cervical  blood-vessels.  At  the  outer  part  of  the 
triangle  the  scalene  muscles  are  seen  descending  from  the  cervical  verte- 
bra to  the  first  rib.  In  front  of  the  insertion  of  the  anterior  scalene 
muscle  the  subclavian  vein  passes  over  the  first  rib.  Between  the  anterior 
and  middle  scalene  muscles  the  subclavian  artery  and  axillary  plexus  of 
nerves  emerge  in  their  course  to  the  axilla. 

The  superior  cer'vical  triangle  corresponds  with  the  submax'illary 
fossa,  Its  upper  part  contains  the  subrnaxillary  gland,  lodged  in  an  oval 


200 

depression  of  the  deeper  layer  of  the  cervical  fascia,  the  outer  portion  of 
which  is  a  partition  separating  it  from  the  parotid  gland,  and  corre- 
sponding with  the  sty'lo-max'illary  ligament.  If  the  deeper  layer  of 
the  cervical  fascia  is  removed,  above  the  submaxillary  gland,  the  muscu- 
lar floor  of  the  mouth  is  seen,  formed  by  the  mylo-hyoid  muscle;  and 
below  the  gland  are  the  stylo-hyoid  and  digastric  muscles.  At  the  outer 
border  of  the  triangle  is  the  external  carotid  artery,  from  which  diverge 
forward,  in  succession  from  below,  the  superior  thyroid,  lingual,  and  facial 
arteries.  Curving  across  the  triangle  below  the  digastric  muscle  is  seen 
the  hypo-glossal  nerve,  giving  off  a  descending  branch  to  the  depressor 
muscles  of  the  hyoid  bone. 

Upon  detaching  the  sterno-mastoid  muscle,  the  great  cervical  vessels 
are  observed  inclosed  within  a  sheath  and  ascending  the  neck  from  the 
position  of  the  sterno-clavicular  junction  toward  the  angle  of  the  jaw. 
The  sheath  being  opened,  is  seen  to  contain  the  primitive  carotid  artery 
at  the  inner  side,  the  internal  jugular  vein  to  the  outer  side,  and  the 
pneumogastric  nerve  between  them.  The  primitive  carotid  artery 
divides  opposite  the  upper  border  of  the  larynx  into  the  external  and 
internal  carotids,  the  former  of  which  ascends  to  penetrate  the  parotid 
gland;  the  latter  takes  a  deeper  course  to  reach  the  carotid  canal  of  the 
temporal  bone.  Behind  the  great  cervical  vessels  lies  the  sympathetic 
nerve,  and  to  their  outer  side  a  chain  of  lymphatic  glands. 


FKONT  OF  THE  THORAX. 

The  front  of  the  Thorax  or  chest,  usually  called  the  breast  or  bosom, 
on  each  side  extends  to  the  shoulder,  the  armpit,  and  the  back.  Be- 
low the  clavicle  it  is  slightly  depressed,  forming  there  the  infra-clavicu- 
lar fossa.  In  lean  persons  it  exhibits  the  outlines  of  the  sternum  and 
ribs,  in  vigorously  muscular  men  the  outlines  of  the  superficial  muscles, 
and  in  fat  persons  hemispherical  elevations  corresponding  with  the 
mamma3.  At  the  lower  part  of  the  sternum,  over  the  position  of  the 
ensiform  cartilage,  is  a  depression,  "the  pit  of  the  stomach."1  From 
this  the  lower  border  of  the  thorax^Hopes  off  on  each  side  downward 
and  outward.  The  skin  of  the  breast  is  thin,  readily  raised  into  folds 
on  each  side,  but  adheres  more  closely  over  the  sternum.  Beneath  it,  is 
a  layer  of  fascia  containing  more  or  less  fat,  excepting  over  the  position 
of  the  sternum.  Beneath  the  fatty  layer2  is  a  thin  layer  of  fascia  invest- 
ing the  muscles. 

1  Scrobiculus  cordis  ;  procardium;  nnticnrd.ium.  2  Panniculus  adiposus. 


THE   MUSCULAR    SYSTEM. 


201 


MUSCLES  OF  THE  FRONT  AND  SIDES  OF  THE  THORAX. 

The  Great  Pec'toral  muscle1  occupies  the  front  of  the  upper  part  of 
the  chest  and  axilla.  It  arises  from  the  sternal  two-thirds  of  the 
clavicle,  the  front  of  the  sternum  and  the  upper  six  costal  cartilages,  and 

FIG.  153. 


MUSCLES  OF  THE  FRONT  OF  THE  THORAX  AND  ABDOMEN.  1,  great  pectoral  muscle;  2,  deltoid  muBcle;  3, 
latissiinus  muscle;  4,  great  serrated  muscle;  5,  subclavian  muscle ;  6,  small  pectoral  muscle;  7,  coraco- 
brachial  muscle;  8,  biceps  flexor;  9,  coracoid  process  of  the  scapula;  10,  origin  of  the  great  serrated 
muscle;  11,  intercostal  muscles:  12,  external  oblique  muscle  of  the  abdomen;  13,  its  aponeurosis;  14, 
lower  border  of  the  latter,  named  Poupart's  ligament ;  15,  external  abdominal  ring,  the  lower  extremity 
of  the  inguinal  canal;  16,  straight  muscle  of  the  abdomen;  17,  pyramidal  muscle;  18,  internal  oblique 
muscle ;  19,  conjoined  tendon  of  the  internal  oblique  and  transverse  muscles ;  20,  position  of  the  inguinal 
canal  below  the  arching  edges  of  the  preceding  two  muscles. 

from  the  aponeurosis  of  the  external  oblique  muscle  of  the  abdomen. 
Proceeding  outwardly,  its  fleshy  fasciculi  converge  to  a  broad  tendon, 


1  Greater  pectoral  muscle;  m.  pectoralis  major;  m.  adductor  brachii;  m.  sterno- 
humeralis;  m.  sterno-costo-clavi-humeralis;    m.  sterno-cleido-brachialis. 


202  THE   MUSCULAR   SYSTEM. 

which  is  inserted  into  the  anterior  margin  of  the  bicipital  groove  of  the 
humerus. 

The  clavicular  portion  of  the  muscle  is  separated  from  the  other  by 
an  interval  filled  with  connective  tissue.  The  outer  portion  of  the 
muscle,  with  its  tendon,  is  doubled  on  itself  so  as  to  produce  the  thick 
anterior  fold  of  the  axilla,  and  the  lower  fleshy  fasciculi  by  this  arrange- 
ment .become  inserted  into  the  humerus  higher  than  the  upper  ones. 

The  Small  Pec'toral  muscle1  lies  beneath  the  preceding  muscle,  and 
arises  by  serrations  from  the  third,  fourth,  and  fifth  ribs.  Proceeding 
upward  and  outward,  its  fibres  converge  to  a  short  tendon,  which  is 
inserted  into  the""  coracoid  process  of  the  scapula. 

The  great  pectoral  muscle  draws  the  arm  downward  and  forward,  in 
which  movement  it  is  aided  by  the  small  pectoral  muscle  drawing  the 
shoulder  in  the  same  direction.  If  the  bones  of  the  shoulder  and  arm 
are  fixed,  the  pectorals  aid  in  respiration  by  elevating  the  ribs. 

The  Sub-clav'ian  muscle2  arises  by  a  short  tendon  from  the  first  costal 
cartilage,  and  is  inserted  along  the  under  surface  of  the  clavicle.  Exter- 
nally it  is  invested  with  a  strong  fascia,  the  cos'to-cor'acoid  membrane,3 
which  starts  from  the  end  of  the  coracoid  process,  and  diverges  upward 
and  inward  to  be  attached  along  the  under  margin  of  the  clavicle  and 
the  anterior  end  of  the  first  rib. 

The  Great  Ser'rated  muscle4  is  a  broad  quadrate  fleshy  layer  situated 
at  the  side  of  the  thorax.  It  arises  by  angular  serrations  from  the  upper 
eight  or  nine  ribs  in  advance  of  their  middle,  and  proceeds  backward  to 
be  inserted  into  the  inner  aspect  of  the  base  of  the  scapula. 

The  five  lower  serrations  alternate  with  as  many  points  of  origin  of 
the  external  oblique  muscle  of  the  abdomen.  Internally  it  is  in  contact 
with  the  ribs  and  intercostal  muscles,  externally  it  is  subcutaneous,  reach- 
ing upward  into  the  axilla  between  the  pectoral  and  latissimus  muscles. 

It  draws  the  scapula,  and  with  it  the  whole  shoulder,  forward,  or,  if 
the  latter  is  fixed,  it  may  contribute  to  respiration  by  aiding  the  pectoral 
muscles  in  elevating  the  ribs,  and  thus  increasing  the  capacity  of  the 
thorax. 

1  Smaller  pectoral  muscle ;  m.  pecto  -  vicular    fascia :    bifid    ligament ;    liga- 

ralis  minor ;  m.  serratus  anticus  minor ;  mentum  bicorne. 

m.  costo-coracoideus.  4  Anterior  great  serrated  muscle ;  m. 

3  M.    subclavius,    subclavicularis,    or  serratus  magnus  anticus ;   m.  s.  major ; 

subclavianus ;  m.  costo-clavicularis.  m.  costo-scapularis ;  m.  costo-basi-scap- 

3  Ligamentum  costo-coracoideum ;  cla-  ularis. 


THE   MUSCULAR  SYSTEM.  203 


THE  BACK. 

The  Back,1  as  the  term  is  commonly  used,  applies  to  the  posterior  part 
of  the  trunk,  but,  in  its  most  restricted  sense,  refers  to  the  posterior  part 
of  the  thorax.2  A  groove  descends  along  the  median  line  of  the  back, 
which  is  deepened  in  fat  persons  from  the  deposit  of  adipose  tissue 
occurring  on  each  side,  while  the  skin  tightly  adheres  to  the  summits  of 
the  spinous  processes.  On  each  side  of  the  thorax,  the  scapula  and  its 
muscles  produce  a  prominence,  which  is  convex  in  stout  individuals, 
but  exhibits  the  outline  of  the  scapula,  with  its  projecting  spine,  in  thin 
persons. 

The  skin  of  the  back  is  thicker  and  denser  than  in  any  other  position 
of  the  body.  It  is  attached  to  the  parts  beneath  by  long,  extensible  con- 
nective tissue,  which  allows  it  readily  to  be  moved  or  raised  into  folds. 

The  muscles  of  the  back  are  invested  with  a  thin  layer  of  fascia,  inde- 
pendently of  the  extensible  areolar  tissue  just  mentioned.  They  are 
divided  into  superficial  and  deep  muscles ;  the  former  being  broad,  and 
for  the  most  part  intended  to  move  the  upper  extremities.  The  latter 
are  comparatively  long  and  narrow,  occupy  the  gutters  along  the  verte- 
bral column,  and  are  intended  to  maintain  the  erect  position  of  this  and 
the  head. 

SUPERFICIAL  MUSCLES  OF  THE  BACK. 

The  Trape'zius  muscle3  arises  from  the  superior  curved  line  and  pro- 
tuberance of  the  occipital  bone,  the  nuchal  ligament,  and  the  summits  of 
the  spinous  processes  of  the  dorsal  vertebrae.  From  this  extensive  ori- 
gin it  converges,  to  be  inserted  into  the  outer  third  of  the  clavicle  and 
into  the  upper  margin  of  the  acromion  and  spine  of  the  scapula. 

Between  the  spinous  processes,  the  muscles  of  the  two  sides  conjoin 
by  means  of  intervening  tendinous  fibres. 

The  lower  fibres  of  the  muscle,  in  their  ascent,  as  they  approach  the 
scapula,  become  tendinous,  and  glide  upon  the  triangular  surface  at  the 
commencement  of  its  spine. 

The  muscles  of  the  two  sides  together  have  the  outline  of  a  trape- 
zium, whence  their  name.  They  fix  the  position  of  the  shoulders,  in  the 
respiratory  action  of  the  pectoral  and  great  serrated  muscles.  They 
also  draw  them  upward,  directly  backward,  or  downward,  according  as 
their  upper,  middle,  or  lower  fasciculi  contract  separately.  If  the 

1  Dorsum ;    tergum ;    notos ;    noton ;  3  M.    trapezius ;    m.    cucullaris  ;    m. 
metaphrenon.                                                   mensalis ;  m.  dorso-supra-acromialis ;  m. 

2  Dorsum ;  dorsal  region.  occipito-dorsi-acromialis. 


204 


THE   MUSCULAR   SYSTEM. 


shoulders  are  fixed,  they  may  draw  the  head  backward ;  or,  if  one  alone 
acts,  it  may  draw  the  latter  to  one  side. 

FIG.  154. 


MUSCLES  OF  THE  BACK.  1,  2,  trapezius;  3,  acromion;  4,  latissimus;  5,  deltoid:  G,  infra-spiuou.-i.  and  to 
its  outer  side  the  terete  muscles ;  7,  external  oblique  muscle  of  the  abdomen  ;  8,  middle  glutoal ;  9,  external 
gluteal  muscle;  10,  elevator  of  the  scapular  angle;  11, 12,  rhomboid  muscles;  13, 14,  splenius ;  15,  aponcu- 
rosis  extending  from  the  superior  to  the  inferior  serrated  muscle,  16;  17,  supra-spinous;  IS,  infra-spinous 
muscle;  19,  lesser  terete,  and  20,  greater  terete  muscle;  21,  triceps  extensor;  22,  great  serrated  muscle; 
23,  internal  oblique  muscle  of  the  abdomen. 

The  Latis'simus  muscle1  occupies  the  lower  part  of  the  back,  extend- 
ing upwardly  along  the  side  of  the  thorax  to  the  back  of  the  humerus. 
It  arises  by  a  thin  aponeurosis  from  the  spinous  processes  of  the  lower 
six  dorsal  vertebrae,  and  all  of  those  of  the  lumbar  vertebra  and  sacrum ; 
from  the  posterior  third  of  the  crest  of  the  ilium,  and  from  the  lumbar 
fascia.  Its  broad,  fleshy  belly  ascends  outwardly,  in  its  course  receiving 

1  M.  latissimus  dorsi;  m.  dorsi-lumbo-sacro-humeralis;  m.  lumbo-humeralis;  m. 
scalptor  ani;  m.  tersor  ani;  m.  brachium  movens  quartus. 


.   THE  MUSCULAR  SYSTEM.  205 

fasciculi  from  the  lower  three  ribs.  It  glides  over  the  inferior  angle  of 
the  scapula,  from  which  it  also  usually  receives  a  slip,  and  converges  to 
a  broad,  tendinous  band  inserted  into  the  posterior  border  of  the  bicip- 
ital  groove  of  the  humerus.  Folding  around  the  greater  terete  muscle, 
it  forms  the  posterior  boundary  of  the  axilla ;  and,  like  the  great  pec- 
toral muscle,  it  has  its  lowest  fasciculi  inserted  highest  into  the  humerus. 

A  synovial  bursa  is  interposed  between  the  muscle  and  the  inferior 
angle  of  the  scapula,  and  another  between  its  tendon  and  that  of  the 
greater  terete  muscle. 

The  latissimus  muscle  draws  the  humerus  downward  and  backward. 
In  conjunction  with  the  pectoral  muscles,  it  is  the  chief  agent  in  climb- 
ing and  in  walking  with  crutches. 

The  Rhom/boid  muscle1  is  situated  beneath  the  trapezius  muscle.  It 
arises  from  the  lower  extremity  of  the  nuchal  ligament  and  the  spinous 
processes  of  the  upper  four  dorsal  vertebra,  and  proceeds  obliquely 
downward  and  outward  to  be  inserted  into  the  base  of  the  scapula  from 
its  spine  to  its  inferior  angle. 

The  muscle  draws  the  scapula  backward  and  upward. 

The  fasciculus  derived  from  the  nuchal  ligament  is  frequently  more  or 
less  separated  by  a  narrow  interval  from  the  lower  portion  of  the  muscle, 
leading  to  the  usual  division  of  the  latter  into  the  lesser  and  greater 
rhomboid  muscles.2 

The  Elevator  of  the  Scap'ular  angle3  is  situated  at  the  side  of  the 
neck,  and  consists  of  a  thick,  fleshy  bundle  arising  tendinously  from  the 
transverse  processes  of  the  upper  four  cervical  vertebra,  and  descending 
to  be  inserted  into  the  upper  angle  of  the  scapula. 

The  Superior  Ser'rated  muscle4  is  situated  beneath  the  rhomboid 
muscle.  It  arises  by  a  thin  aponeurosis  from  the  lower  part  of  the  nu- 
chal ligament  and  the  upper  three  dorsal  spinous  processes,  and  descends 
•obliquely  outward  to  be  inserted,  by  angular  serrations,  into  the  upper 
border  of  the  second,  third,  fourth,  and  fifth  ribs,  beyond  their  angle. 

A  thin  aponeurosis  extends  between  this  and  the  succeeding  muscle, 
covering  the  extensors  beneath. 


1  M.  rhomboideus ;    m.  cervici-dorso-  gularis  ;  m.  patientiae  ;  m.  trachelo-scap- 
scapularis.  ularis ;  elevator  muscle  of  the  angle  of 

2  M.  rhomboideus  minor  and  major,  or  the  scapula. 

superius  and  inferius.  *  M.  serratus   posticus  superior;   m. 

3  M.   levator   scapulae;    m.   1.    anguli  dorso-costalis ;  m.  cervici-dorso-costalis. 
scapulae;  m.  1.  proprius  icapuloa  ;  m.  an- 


206  THE   MUSCULAR  SYSTEM. 

The  Inferior  Ser'rated  muscle1  is  situated  at  the  lower  part  of  the 
back,  beneath  the  latissinius  muscle.  It  arises  by  a  thin  aponeurosis 
from  the  lower  two  dorsal  and  the  upper  three  lumbar  spinous  processes, 
and  ascends  obliquely  outward  to  be  inserted  by  serrations  into  the  lower 
border  of  the  four  inferior  ribs. 

The  two  serrated  muscles  are  antagonistic  in  their  action.  The  supe- 
rior one  aids  in  elevating  the  ribs,  the  inferior  in  depressing  them,  and 
thus  both  assist  in  respiration. 


DEEP  MUSCLES  OF  THE  BACK,  OE  EXTENSORS  OF  THE  HEAD 

AND  TRUNK. 

The  extensor  muscles,  which  maintain  the  erect  position  of  the  head 
and  trunk,  are  situated  at  the  back  of  the  latter,  and  occupy  the  sides  of 
the  neck,  the  intervals  between  the  angles  of  the  ribs  and  spinous  proc- 
esses of  the  vertebras,  and  the  sides  of  the  loins,  extending  into  the 
angular  intervals  of  the  sacrum  and  hip  bones. 

They  lie  beneath  the  trapezius,  latissinius,  rhomboid,  and  serrated 
muscles,  and  consist  of  numerous  fleshy  and  tendinous  fasciculi,  which  are 
more  or  less  intimately  connected,  so  that  they  may  be  described  as  com- 
paratively few  or  many  distinct  muscles. 

The  Dor'sal  Exten'sor2  is  a  large  muscle  occupying  the  groove  of  the 
back  at  the  side  of  the  vertebral  column.  It  is  exceedingly  complex  in 
its  arrangement,  consisting  of  intermingled  fleshy  fasciculi  and  tendinous 
bands,  and  having  many  points  of  attachment  to  the  vertebral  column 
and  ribs.  Its  lower  portion  is  superficially  composed  of  a  strong  apo- 
neurosis, from  which  many  fleshy  fasciculi  have  their  origin. 

The  muscle  commences  in  a  pointed  manner  upon  the  sacrum,  is 
thickest  in  the  loins,  and  gradually  thins  away  on  the  thorax,  from 
which,  by  accessory  fasciculi,  it  is  continued  to  the  neck.  It  arises  from 
the  posterior  surface  of  the  sacrum,  the  posterior  third  of  the  crest  of 
the  ilium,  and  the  spinous  processes  of  the  lumbar  and  lower  two  or 
three  dorsal  vertebrae,  and  in  the  vicinity  of  the  last  rib  divides  into  two 
portions,  named  the  longissimus  and  sacro-lumbar  muscles. 

The  Longis'simus  muscle3  is  the  internal  and  larger  portion  of  the 
dorsal  extensor.  It  is  inserted  into  the  transverse  processes  of  the 

1  M.   serratus   posticus   inferior ;    m.  3  M.  longissimus  dorsi ;   m.  semi-spi- 
lumbo-costalis;  m.  dorso-lumbo-costalis.  natus;    m.  lumbo-dorso-trachelius ;    in. 

2  M.  extensor  dorsi,  or  trunci  commu-  extensor  dorsi  intcrnus. 
nis;  m.  erector  spinse ;  m.  sacro-spinalis; 

m.  lumbo-costalis;  m.  opistothenar. 


THE    MUSCULAR  SYSTEM. 


207 


lumbar  and  dorsal  vertebrae,  into  the  ends  of  the  upper  dorsal  spinous 
processes,1  into  the  ribs  within  the  position  of  their  angles ;   and  by 


accessory  slips,  derived 
from  the  upper  dorsal 
transverse  processes,  is 
prolonged  to  the  lower 
four  or  five  cervical 
transverse  processes.2 

The  Sa'cro-lum/bar 
muscle,3  in  its  ascent, 
receives  accessory  slips4 
from  the  upper  border 
of  the  ribs,  and  is  in- 
serted by  a  series  of 
tendons  into  the  angles 
of  the  ribs  and  into  the 
four  or  five  lower  cer- 
vical transverse  proc- 
esses.5 


EXTENSOR  MUSCLES  OF  THE 
BACK.  1,  2,  3,  4,  5,  6,  the  dor- 
sal extensor  muscle.  1,  origin 
from  the  ilium,  sacrum,  lum- 
bar, and  lower  dorsal  verte- 
brae ;  2,  insertion  into  the  ribs, 
named  the  sacro-lumbar  mus- 
cle; 3,  insertion,  named  the 
longissimus  muscle ;  4,  offset, 
named  the  dorsal  spinal  mus- 
cle ;  5,  6,  prolongations  to  the 
neck,  named  the  ascending  and 
transverse  cervical  muscles ;  7, 
trachelo-mastoid  muscle;  8, 
complex  muscle;  9,  prolonga- 
tion of  the  longissimus,  named 
the  transverse  cervical  muscle; 
10,  11,  semispinal  muscle;  12, 
13,  smaller  and  larger  straight 
muscles  of  the  head ;  14, 15,  su- 
perior and  inferior  oblique 
muscles ;  16,  multifid-spinal 
muscle;  17,  elevators  of  the 
ribs ;  18,  inter-transverse  mus- 
cles; 19,  quadrate  lumbar 
muscle. 


FIG.  155. 


The  Sple'nius  mus- 
cle6 is  situated  at  the 

back  of  the  neck,  beneath  the  trapezius  muscle. ' 
It  arises  from  the  upper  six  dorsal  spinous 
processes  and  the  lower  half  of  the  nuchal 
ligament.  Proceeding  upward  and  outward, 
it  divides  into  two  portions,  of  which  one7  is 
inserted  into  the  upper  four  cervical  transverse  processes,  and  the  other8 
is  inserted  into  the  mastoid  portion  of  the  temporal  bone  and  the  con- 
tiguous part  of  the  surface  between  the  curved  lines  of  the  occipital  bone. 


1  M.  spinalis  dorsi.    Usually  described 
as  distinct,   ascending  from  the  upper 
two  lumbar  and  the  three  lower  dorsal 
spinous  processes,  to  the  upper  eight  or 
nine  dorsal  spinous  processes. 

2  M.  transversalis  cervicis,  orcolli;  m. 
t.  major  colli,   are  names  given  to  the 
portion  prolonged  to  the  neck. 

3  M.  sacro-lumbalis;  m.  sacro-costalis  ; 
m.  ilio-costalis;    m.  lumbo-costo-trache- 
lius  ;  m.  extensor  dorsi  externus. 

*  M.  accessorii,  or  additamentum  ad 
sacro-lumbalem. 


5  M.  cervicalis  ascendens,  or  descend- 
ens  Diemerbroeckii ;    m.  accessorius  ad 
sacro-lumbalem ;  m.  transversalis  colla- 
teralis  colli,  are  names  given  to  the  por- 
tion prolonged  into  the  neck. 

6  Posterior  mastoid  muscle  ;  m.  cervi- 
co-dorso-mastoideus. 

7  M.  splenius  colli ;    m.  dorso-trachc- 
lius. 

8  M.  splenius  capitis ;  in.  cervico-mas- 
toideus. 


208  THE    MUSCULAR   SYSTEM. 

The  Com'plex  muscle,1  partly  concealed  by  the  last,  arises  from  the 
transverse  processes  of  the  upper  four  to  six  dorsal  vertebrae  and  the 
transverse  and  articular  processes  of  the  lower  four  cervical  vertebras, 
and  ascends  to  be  inserted  into  the  inner  part  of  the  surface  between  the 
curved  lines  of  the  occipital  bone.  Its  upper  portion  is  partially  inter- 
sected by  a  transverse  tendinous  structure  ;  and  a  large  fasciculus  of  the 
muscle  is  divided  into  two  bellies  by  an  intermediate  tendon.2 

The  splenius  and  complex  muscles  of  the  two  sides  of  the  neck  are 
important  agents  in  maintaining  the  erect  position  of  the  head. 

The  Tr  ache  lo-mas't  old  muscle,3  situated  between  the  upper  end  of 
the  dorsal  extensor  and  the  complex  muscle,  is  intimately  connected  with 
the  former,  and  may  with  propriety  be  considered  its  prolongation  to  the 
head.  It  arises  by  narrow  tendons  from  the  roots  of  the  transverse 
processes  of  the  lower  four  cervical  vertebrae,  and  ascends  outwardly  to 
be  inserted  into  the  mastoid  process  of  the  temporal  bone  beneath  the 
sterno-mastoid  and  splenius  muscles. 

The  Semispi'nal  muscle4  consists  of  fleshy  and  tendinous  fasciculi, 
obliquely  extended  between  transverse  and  spinous  processes  in  the  back 
and  neck,  beneath  the  dorsal  extensor  and  complex  muscles.  It  arises 
from  the  dorsal  transverse  processes,  except  the  one  or  two  lower  ones, 
and  is  inserted  into  the  upper  five  dorsal  spinous  processes  and  the  lower 
five  of  those  of  the  neck.  The  upper  and  lower  portions  are  sometimes 
separated  by  an  interval,  and  these  are  usually  described  as  distinct,  with 
the  names  of  semispinal  muscle  of  the  neck5  and  of  the  back.6 

The  Mul'tifid  spi'nal  muscle,'  partially  concealed  beneath  the  last, 
consists  of  numerous  short,  oblique  fasciculi,  extended  from  the  trans- 
verse and  articular  processes  to  the  contiguous  spinous  processes,  from 
the  sacrum  to  the  axis.  The  fasciculi  vary  in  length,  some  extending 


3  M.  coraplexus;  ra.  c.  major;  m.  tra-  6  M.  semispinalis  dorsi,  or  externus : 

chelo-occipitalis ;    m.   dorso-trachelo-oc-  m.  transverso-spinalis  dorsi ;  m.  semispi- 

cipitalis.  natus  dorsi. 

2  This  double-bellied  fasciculus  consti-  ?  M.  multifidus  spinrc  :  m.  transveralis 
tutes  the  m.  biventer  cervicis.  dorsi;    m.  transverso-spinalis;    m.  t.  s. 

3  M.  trachelo-mastoideus ;  m.  complex-  lumbarum  dorsi  et  colli ;  nv.  spinales  et 
us  minor.  transversales  lumbarum;    m.  sacer;  m. 

4  M.  semispinalis  dorsi  et  colli.  semispinalis  internus  et  transverso-spi- 

5  M.  semispinalis  colli,  or  cervicis;  m.  nalis  colli  pars  interna ;  m.  lumbo-dorsi- 
spinalis,  or  transversalis  colli,  or  cervi-  spinalis ;  lumbo-cervical  portion  of  the 
cis;    m.  transverse-  or  articulo-spinalis  spinal  muscle;  in  part,  the  musculi  ro- 
colli ;  m.  semispinatus  colli.  tatores  spinae. 


THE   MUSCULAR   SYSTEM.  209 

between  two  vertebrae,  others  between  three,  and  a  few  between  four,  or 
even  five. 

This  and  the  preceding  muscles  are  extensors  of  the  vertebral  column. 

The  Inter-spi'nal  muscles1  consist  of  short,  fleshy  bundles,  situated  in 
pairs  between  the  contiguous  spinous  processes  of  the  vertebrae.  They 
are  best  developed  in  the  neck,  and  usually  are  obsolete  in  the  dorsal 
region. 

The  Inter-trans 'verse  muscles2  consist  of  short,  fleshy  bundles,  occu- 
pying the  intervals  of  the  contiguous  transverse  processes.  They  are 
best  developed  in  the  neck,  where  they  are  double,  are  rudimental  in  the 
dorsal  region,  and  are  well  marked  in  the  loins. 

These  and  the  preceding  small  muscles  aid  in  the  extension  of  the  ver- 
tebral column. 

The  Larger  Straight  muscle3  arises  tendinously  from  the  spinous 
process  of  the  axis,  and  ascends  to  be  inserted  into  the  inferior  curved 
line  of  the  occipital  bone. 

The  Smaller  Straight  muscle4  arises  from  the  rudimental  spinous 
process  of  the  atlas,  and  is  inserted  into  the  occipital  bone  below  its 
inferior  curved  line. 

The  Lateral  Straight  muscle5  arises  from  the  transverse  process  of  the 
atlas,  and  is  inserted  into  a  ridge  of  the  corresponding  process  of  the 
occipital  bone. 

The  Superior  Oblique  muscle6  arises  from  the  extremity  of  the  trans- 
verse process  of  the  atlas,  and  ascends  obliquely  inward  to  be  inserted 
into  the  outer  part  of  the  surface  between  the  curved  lines  of  the  occip- 
ital bone. 

The  Inferior  Oblique  muscle7  arises  from  the  spinous  process  of  the 

1  M.  interspinales  ;  m.  i.  colli,  dorsi  et  5  M.  rectus  lateralis  ;  m.  rectus  capi- 
lumbarum.  tis  lateralis ;    m.  lateralis  Fallopii ;  m. 

2  M.  intertransversarii.  transversalis  anticus  primus;  m.  trache- 

3  M.  rectus  major;    m.  rectus  capitis  lo-atloido-basilaris ;    m.  atloido-subocci- 
posticus  major;    m.   axoido-occipitalis ;  pitalis. 

m.  spini-axoido-occipitalis ;  larger  pos-  6  M.  obliquus  capitis  superior,  or  mi- 
terior  straight  muscle.  nor;  m.  atlo-,  post-,  or  submastoideus; 

4  M.  rectus  minor;  m.  r.  c.  p.  minor;       m.  trachelo-atloido-occipitalis. 

m.  atlo-occipitalis ;  m.  tuber-atloido-oc-  7  M.  o.  c.  inferior,  or  major ;  m.  axo- 
cipitalis;  smaller  posterior  straight  mus-  atloideus  ;  m.  spini-axoido-tracheli-atloi- 
cle.  deus. 

14 


210  THE    MUSCULAR   SYSTEM. 

axis,  and  passes  obliquely  outward  and  upward  to  be  inserted  into  the 
extremity  of  the  transverse  process  of  the  atlas. 

The  straight  and  oblique  muscles  contribute  to  maintain  the  erect  con- 
dition of  the  head.  The  inferior  oblique  and  larger  straight  muscles 
rotate  the  latter,  together  with  the  atlas  upon  the  axis. 

MUSCLES  OF  THE  RIBS. 

The  Intercostal  muscles,  of  which  there  are  eleven  pairs  on  each 
side  of  the  thorax,  occupy  the  intervals  of  the  ribs.  They  consist  of 
two  planes  of  short,  fleshy  and  tendinous  fibres,  extended  between  the 
contiguous  borders  of  the  ribs  and  costal  cartilages. 

The  External  Intercostal  muscles1  commence  at  the  tubercles  of  the 
ribs,  and,  with  their  fibres  directed  obliquely  downward  and  forward, 
advance  to  the  costal  cartilages,  between  which  they  terminate  in  a  thin 
aponeurosis. 

The  Internal  Intercostal  muscles2  commence  at  the  sternal  ends  of 
the  costal  cartilages,  and,  with  their  fibres  directed  obliquely  downward 
and  backward,  crossing  the  course  of  those  of  the  preceding  muscles, 
proceed  to  the  angles  of  the  ribs,  where  they  terminate  in  a  thin  aponeu- 
rosis, extending  to  the  vertebra?. 

On  the  inner  surface  of  the  ribs,  more  or  less  frequently,  a  variable 
number  of  fasciculi  of  fibres  of  the  internal  intercostals  extend  over  two 
or  even  three  intercostal  spaces.3 

Between  the  intercostal  muscles  the  intercostal  blood-vessels  and 
nerves  pursue  their  course.  The  internal  intercostal  muscles  are  in  con- 
tact with  the  pleura ;  the  external  ones  with  the  pectoral  and  great  ser- 
rated muscles. 

The  Ster'no-cos'tal  muscle,4  variable  in  its  extent  and  attachments,  is 
situated  within  the  front  of  the  thorax.  It  arises  by  a  thin  aponeurosis 
from  the  inner  surface  of  the  lower  two  divisions  of  the  sternum  and  the 
contiguous  ends  of  the  costal  cartilages,  whence  its  fibres  diverge  upward 
and  outward,  to  be  inserted  by  digitations  into  the  costal  cartilages  from 
the  fifth  to  the  second  inclusively. 

The  Cos'tal  El'evators5  are  twelve  in  number,  on  each  side  of  the 
thorax,  and  lie  beneath  the  extensor  muscles  of  the  back.     They  con- 

1  M.  intercostales  externi.  *  M.  sterno-costalis ;    m.   triangularis 

2  M.  intercostales  interni ;    m.  inter-  sterni ;  m.  pectoralis  internus. 
pleuro-costales.  5  Elevator  muscles  of  the  ribs;  m.  le- 

3  M.  infracostales;  m.  subcostales.  vatores  costarum  breviores  et  longiores  ; 

m   supra-costales. 


THE    MUSCULAR   SYSTEM.  211 

sist  of  narrow  bundles  arising  tendinously  from  the  ends  of  the  trans- 
verse processes  of  the  last  cervical  and  all  the  dorsal  vertebrae,  except 
the  last  one.  Descending  obliquely  outward,  their  fibres  diverge  to  be 
inserted  into  the  contiguous  ribs,  between  their  tubercles  and  angles. 
The  lower  muscles  of  the  series  send  an  additional  fasciculus  to  the 
second  ribs  below  their  origin. 

The  intercostal  muscles  act  together,  and  either  raise  or  depress  the 
ribs  according  as  the  first  or  last  of  the  series  of  the  latter  becomes  the 
more  fixed  point  of  action.  Thus,  if  the  scalene  muscles  draw  up  the 
first  and  second  ribs,  this  will  determine  the  intercostals  to  raise  all  the 
ribs.  If,  on  the  other  hand,  the  quadrate  lumbar  muscles  draw  down  the 
last  ribs,  then  all  the  others  will  be  depressed  by  the  intercostals. 

The  costal  elevators,  as  expressed  by  their  name,  and  the  superior 
serrated  muscles,  raise  the  ribs.  The  sterno-costal  and  inferior  serrated 
muscles  depress  the  ribs. 

From  the  above,  it  will  have  been  perceived  that  all  the  muscles  men- 
tioned concur  in  promoting  the  function  of  respiration. 

THE  ABDOMEN. 

The  Abdo'men  or  belly1  is  that  part  of  the  trunk  which  is  included 
between  the  thorax  and  pelvis. 

The  large  vacuity  observed  in  the  skeleton  between  the  inferior  mar- 
gin of  the  thorax  and  the  superior  border  of  the  pelvis,  is  closed  by  the 
soft,  extensible  abdom/inal  pari'etes  or  walls,  composed  of  skin,  the 
superficial  fascia,  six  pairs  of  muscles,  the  transverse  fascia,  and  the 
peritoneum.  The  abdominal  parietes  are  longest  anteriorly,  and  become 
gradually  shortened  as  they  approach  the  back  part,  named  the  loins  or 
lumbar  regions,2  situated  on  each  side  of  the  vertebral  column.  In  the 
upright  position  the  abdominal  walls  are  convex  and  protuberant,  vary- 
ing in  these  respects  according  to  the  fatness  of  the  individual.  In  the 
recumbent  position  they  sink  inwardly,  and  in  very  lean  persons  even 
the  vertebral  column  may  be  felt  through  them!  Inspiration  increases 
their  protuberance,  and  expiration  their  depression. 

In  vigorous  men,  the  outlines  of  the  muscular  bellies  of  the  abdominal 
parietes  are  visible  through  the  skin.  In  fat  persons,  usually  including 
healthy  women,  these  are  obscured  by  the  subcutaneous  fat.  Over  the 
position  of  the  end  of  the  sternum  is  a  depression  called  the  pit  of  the 

1  Venter;  gaster;  abdomen;   alvus ;   venter  imus,  or  infimus ;   epischion;  hypo- 
gastrion;  hypocrelium;  hypoutrion ;  hypochoilion;  etron;  nedys;  neira;  physce. 
*  Lumbi;  lendis;  psoae;  reins. 


212  THE   MUSCULAR  SYSTEM. 

stomach,1  which  becomes  more  evident  with  an  increase  of  fat.  Near 
the  centre  of  the  abdomen,  in  front,  is  the  umbilicus  or  navel,2  which  is 
a  cicatrix  remaining  from  the  connection  of  the  umbilical  cord  of  the 
foetus.  From  the  close  adhesion  of  the  skin  to  the  umbilicus,  its  depth 
increases  with  the  accumulation  of  fat  around. 

The  lower  part  of  the  abdominal  walls  is  defined  on  each  side  by  the 
prominence  corresponding  with  the  crest  of  the  ilium  and  named  the 
hip ;  and  in  advance  of  this  by  the  groin  and  prominence  of  the  pubes. 

The  groin  or  in'guinal  region3  corresponds  with  the  crease  descend- 
ing from  the  hip  to  the  pubis  and  separating  the  abdomen  from  the 
front  of  the  thigh. 

The  skin  of  the  abdomen  is  rather  thin  and  moderately  extensible ; 
in  lean  persons  is  readily  elevated  into  folds,  but  not  in  fat  persons.  Its 
extensibility  is  not  so  great  as  might  be  supposed  from  the  frequent 
occurrence  of  distention  of  the  abdominal  walls  from  the  accumulation 
of  fat,  pregnancy,  dropsy,  or  other  causes.  In  such  cases  partial  rup- 
tures of  the  dermis  take  place;  and  even  after  the  distention  is  removed, 
the  position  of  these  ruptures  is  indicated  by  their  cicatrix-like  marks 
on  the  skin. 

SUPERFICIAL  FASCIA  OF  THE  ABDOMEN. 

The  Superficial  Fascia4  is  well  developed,  especially  toward  the  lower 
part  of  the  abdomen,  where  it  is  observed  to  consist  of  two  distinct 
layers.  It  is  continuous  above  with  the  superficial  fascia  of  the  thorax, 
and  behind  with  that  of  the  back.  Its  two  layers,  blended  together, 
adhere  along  the  median  line  of  the  abdomen,  along  the  crest  of  the 
ilium,  and  Poupart's  ligament,  and  become  continuous  with  the  super- 
ficial fascia  of  the  thigh,  that  of  the  spermatic  cord,  and  the  penis. 
Where  the  two  layers  are  separable,  the  subcutaneous  one  is  found  to 
be  composed  of  loose  areolar  tissue  containing  more  or  less  fat,  which 
increases  in  descending  toward  the  pubis.  At  the  umbilicus  it  never 
contains  fat,  so  that  the  fatter  the  individual  the  more  depressed  the 
umbilicus  will  appear.  The  deeper  layer  is  thinner  and  more  membran- 
ous in  its  character  than  the  other,  and  is  not  disposed  to  the  develop- 
ment of  fat  in  its  interstices.  Between  the  two  layers  are  contained  the 
subcutaneous  blood-vessels,  among  which,  the  superficial  epigastric  artery 
and  vein  are  conspicuously  observed  ascending  obliquely  from  the  groin. 

1  Scrobiculus  cordis.  3  Inguen ;  plica  inguinalis ;  bubo. 

2  Umbilic ;  umbo ;  omphalos  ;  mesom-  *  Fascia  superfacialis  abdominis. 
phalium;  radix,  or  medium  ventris. 


THE   MUSCULAR   SYSTEM.  213 


MUSCLES  OF  THE  ABDOMEN. 

The  front  and  lateral  walls  of  the  abdomen  are  composed  of  six  pairs 
of  muscles,  of  which  three  are  broad  muscles,  and  the  others  are  long 
ones. 

The  External  Oblique  muscle,1  the  stoutest  of  the  three  broad  ab- 
dominal muscles,  consists  of  a  fleshy  portion  occupying  the  side  of  the 
abdomen,  and  a  strong  aponeurotic  portion  extending  over  the  front  of 
the  latter. 

It  arises  by  angular  digitations  from  the  outer  surface  of  the  lower 
eight  ribs  ;  the  digitations  being  received  between  similar  processes  of 
the  origin  of  the  great  serrated  and  latissimus  muscles.  The  fleshy  fas- 
ciculi incline  downward  and  inward,  the  lowest  ones  being  inserted  into 
the  crest  of  the  ilium,  while  the  others  terminate  in  an  aponeurosis,  which 
extends  to  the  median  line  of  the  abdomen,  from  the  sternum  to  the 
pubis,  and  conjoins  with  that  of  the  opposite  side. 

The  upper  three-fourths  of  the  aponeurosis  present  the  appearance  of 
a  broad  band  at  the  side  of  the  median  line  of  the  abdomen ;  and  its 
lower  fourth  widens  outward  to  the  anterior  superior  spinous  process  of 
the  ilium.  Though  mainly  composed  of  fibres  continuing  in  the  direc- 
tion of  the  fleshy  fasciculi,  it  nevertheless  contains  many  crossing  ones, 
apparently  derived  from  the  aponeurosis  of  the  opposite  muscle.  In 
several  positions  the  fibres  by  their  separation  leave  small  square  inter- 
vals, through  which  blood-vessels  reach  the  superficial  fascia  and  integu- 
ment. 

The  upper  part  of  the  aponeurosis  is  connected  with  the  origin  of 
the  great  pectoral  muscle,  and  is  attached  to  the  third  piece  of  the 
sternum. 

As  the  aponeurosis  approaches  the  pubis  its  fibres  diverge,  leaving 
between  them  a  triangular  interval,  the  external  abdom/inal  ring,2  which 
gives  passage  to  the  spermatic  cord  of  the  male,  and  the  round  ligament 
of  the  uterus  of  the  female.  The  direction  of  the  ring  is  obliquely 
downward  and  inward  ;  its  base  being  formed  by  the  body3  of  the  pubis, 
and  its  sides  or  columns4  by  the  diverging  fibres  of  the  aponeurosis. 
The  inner  or  upper  column  is  attached  in  front  of  the  pubic  symphysis, 
and  interlaces  with  the  corresponding  insertion  of  the  opposite  muscle. 
The  outer  or  lower  column  is  formed  by  the  inferior  and  somewhat  thick- 

1  M.  obliquus  abdominis  externus,  de-  2  Abdominal   ring ;    annulus   abdorai- 

scendens,    or  major;  m.   costo-abdomi-       nis,  or  inguinalis ;  inguinal  ring, 
nalis  ;  m.  ilio-pubo-costo-abdominalis.  3  Crest  of  the  pubis. 

4  Pillars ;  crura. 


214 


THE   MUSCULAR   SYSTEM. 


ened  fibres  of  the  aponeurosis,  extended  between  the  anterior  superior 
spinous  process  of  the  ilium  and  the  spine  of  the  pubis,  constituting  the 
so-called  Poupart's  ligament1  or  femoral  arch,2  important  in  its  relations 
with  inguinal  and  femoral  herniae 


FIG.  15H. 


MUSCLES  OF  THE  FRONT  OF  THE  TRUNK;  on  the  left  side  are  seen  the  superficial  muscles,  on  the  right  the 
deeper  ones.  1,  great  pectoral;  2,  deltoid;  3,  latissimus ;  4,  great  serrated;  5,  subclavian ;  6,  small  pec- 
toral; 7,  coraco-brachial;  8,  biceps  flexor  muscle;  9,  coracoid  process;  10, great  serrated  muscle;  11,  inter- 
costals;  12,  external  oblique;  13,  its  aponeurosis;  14,  Poupart's  ligament;  15,  external  abdominal  ring;  the 
figure  rests  upon  the  falciform  process  of  the  fascia  of  the  thigh  bounding  the  saphenous  opening  exter- 
nally; 16,  straight  muscle  of  the  right  side,  exposed  by  removing  the  front  of  its  sheath,  which  remains 
on  the  left  side;  17,  pyramidal  muscle;  18,  internal  oblique;  19,  conjoined  tendon  of  the  internal  oblique 
and  transverse  muscles;  20,  position  of  the  inguinal  canal  below  the  arching  edges  of  the  muscles  just 
named. 

Above  the  position  of  the  external  abdominal  ring,  transversely  cross- 
ing fibres  proceed  from  the  line  of  Poupart's  ligament  toward  the  median 
line  of  the  abdomen,  apparently  with  the  object  of  preventing  a  greater 
separation  of  the  columns  of  the  ring.  From  the  edges  of  the  latter,  a 


Ligament  of  Fallopius. 


Crural,  or  inguinal  arch. 


THE   MUSCULAR   SYSTEM.  215 

thin  layer  of  connective  tissue1  is  prolonged  upon  the  spermatic  cord,  or 
round  ligament. 

Poupart's  ligament  in  its  course  makes  a  curve  with  the  convexity 
downward,  and  is  somewhat  inflected  or  directed  inwardly.  Below,  it  is 
continuous  with  the  femoral  fascia.  At  its  insertion,  a  process  of  the 
same  structure  extends  a  short  distance  along  the  pectineal  line  of  the 
pubis,  and  terminates  in  a  crescentic  margin,  constituting  the  so-called 
Gimbernat's  ligament,2  important  in  its  relations  with  femoral  hernia. 

The  Internal  Oblique  muscle3  is  placed  beneath  the  last,  and,  like  it, 
is  fleshy  at  the  side  of  the  abdomen,  and  aponeurotic  in  front. 

It  arises  from  the  outer  half  of  Poupart's  ligament,  the  crest  of  the 
ilium,  and  the  lumbar  fascia.  From  this  origin  the  fleshy  fasciculi 
radiate  forward,  the  more  posterior  ascending  obliquely  and  becoming 
attached  to  the  margin  of  the  lower  four  costal  cartilages  contiguous  to 
their  internal  intercostal  muscles,  while  the  others  terminate  in  an  apo- 
neurosis  extending  from  the  sternum  to  the  pubis.  At  its  upper  extrem- 
ity the  aponeurosis  is  attached  to  the  end  of  the  sternum  and  the  seventh 
and  eighth  costal  cartilages.  For  three-fourths  of  its  extent  it  splits  at 
the  semilunar  line  into  two  laminaB,  of  which  one  proceeds  in  front  of  the 
straight  muscle  and  identifies  itself  with  the  aponeurosis  of  the  external 
oblique  muscle,  while  the  other  proceeds  behind  the  straight  muscle,  and 
in  like  manner  identifies  itself  with  the  aponeurosis  of  the  transverse 
muscle.  The  lower  fourth  of  the  aponeurosis  passes  without  division  in 
front  of  the  straight  muscle. 

The  inferior  fibres  of  the  internal  oblique  muscle  arch  forward  and 
downward  over  the  course  of  the  spermatic  cord,  or  round  ligament  of 
the  uterus,  and,  in  conjunction  with  corresponding  fibres  of  the  trans- 
verse muscle,  form  the  conjoined  tendon,4  which  is  inserted  into  the  body 
and  pectineal  line  of  the  pubis,  within  the  position  of  the  external  ab- 
dominal ring,  thus  affording  a  protection  against  the  escape  of  any  por- 
tion of  the  bowels  through  this  aperture. 

The  Transverse  muscle5  lies  beneath  the  preceding  muscles,  and  like 
them  presents  the  same  relation  of  fleshy  and  aponeurotic  portions. 

It  arises  from  the  outer  half  of  Poupart's  ligament,  the  crest  of  the 
ilium,  the  lumbar  fascia,  and  the  inner  surface  of  the  lower  six  costal 

1  Intercolumnar  fascia ;  fascia  sperma-  m.  ilio-lumbo-costo-abdominalis  ;  m.  ac- 
tica.  clivis. 

2  Hey's  ligament.  *  Superficies  intercruralis. 

3  M.  obliquus  abdotninus  interims,  as-  5  M.  transversalis  abdominis;  m.  lum- 
cendens,  or  minor;  m.  ilio-abdominalis  ;  bo-abdominalis. 


216 


THE   MUSCULAR   SYSTEM. 


FIG.  157. 


cartilages,  where  it  indigitates  with  the  origin  of  the  diaphragm.  The 
fleshy  fasciculi,  as  indicated  by  the  name  of  the  muscle,  proceed  trans- 
versely forward  and  terminate  in 
an  aponeurosis,  of  which  the  upper 
three-fourths  join  the  posterior  lam- 
ina of  the  aponeurosis  of  the  in- 
ternal oblique  muscle,  and  with  it 
proceed  to  the  median  line  of  the 
abdomen,  while  the  lower  fourth 
passes  in  front  of  the  straight  muscle, 
and,  in  conjunction  with  the  corres- 
ponding portion  of  the  aponeuroses 
of  the  other  broad  muscles,  likewise 
proceeds  to  the  median  line  of  the 
abdomen. 

The  inferior  fibres  of  the  trans- 
verse muscle,  like  those  of  the  in- 
ternal oblique,  arch  forward  and 
downward  to  the  conjoined  tendon. 
Internally  this  muscle  is  invested 
with  a  thin,  fibrous  membrane,  the 
transverse  fascia,1  which  attaches 
it  to  the  peritoneum. 


VIEW  OF  THE  LEFT  SIDE  OF  THE   ABDOMEN.      1,  por- 

tion  of  the  latissimus  muscle ;  2,  origin  of  the  great 
serrated  muscle  ;  3,  origin  of  the  external  oblique ; 
4,  external  intercostals ;  5,  internal  intercostals ;  6, 
transverse  muscle ;  7,  its  aponeurotic  origin ;  8,  its 
aponeurotie  insertion ;  9,  lower  part  of  the  internal 
oblique  muscle ;  10,  straight  muscle  of  the  right 
side;  11,  position  of  the  inguinal  canal  between 
the  arched  border  of  the  internal  oblique  and  trans- 
verse muscles  and  Poupart's  ligament ;  the  figure 
rests  on  the  transverse  fascia ;  12,  the  gluteal  mus- 
cles. 


The  Straight  muscle2  is  a  broad, 
fleshy  band,  situated  at  the  side  of 
the  median  line  of  the  abdomen, 
and  extending  from  the  pubis  to 
the  front  of  the  thorax.  It  arises 
by  a  flat  tendon  from  the  symphysis 
and  body  of  the  pubis,  expands 
gradually  to  the  breadth  of  three 
or  four  inches,  and  ascends  to  be 
inserted  in  front  of  the  fifth,  sixth,  and  seventh  costal  cartilages.  In  its 
course  it  presents  three  or  four  short  tendinous  intersections,3  which  ex- 
tend through  the  breadth  and  thickness  of  the  muscle,  and  adhere  tightly 
to  the  aponeurosis  covering  the  latter.  These  tendinous  intersections 
appear  to  represent  the  abdominal  ribs  of  lizards. 

The  straight  muscle  is  'inclosed  in  a  sheath,4  formed  by  the  aponeu- 

1  Fascia  transversalis. 

2  M.  rectus  abdominis ;  m.  pubio-sternalis. 

3  Inscriptiones  tendinese.  4  Vagina  musculi  recti. 


THE  MUSCULAR  SYSTEM.  217 

roses  of  the  broad  muscles,  which  is  incomplete,  however,  at  its  lower 
fourth  posteriorly,  where  the  muscle  is  in  contact  with  the  transverse 
fascia.  The  deficiency  in  the  sheath  is  more  or  less  defined  by  a  thin, 
lunated  edge,1  which  is  confluent  with  the  transverse  fascia  extending 
toward  the  pubis. 

In  consequence  of  the  deficiency  in  the  aponeurotic  sheath  of  the 
straight  muscle  a  space  is  left,  recently  described2  as  the  preperitone'al 
cavity,3  which  accommodates  the  urinary  bladder  in  a  distended  con- 
dition. 

The  Pyram'idal  muscle*  is  situated  beneath  the  aponeuroses  of  the 
broad  muscles  upon  the  lower  extremity  of  the  straight  muscle.  It 
arises  from  the  symphysis  and  body  of  the  pubis,  and  ascends  one-third 
the  distance  toward  the  umbilicus,  to  be  inserted  into  the  median  line  of 
the  abdomen.  This  muscle  sometimes  exists  only  on  one  side,  and  not 
unfrequently  it  is  altogether  absent. 

At  the  median  line  of  the  abdomen,  the  aponeuroses  of  the  three  pairs 
of  broad  muscles  are  intimately  associated  with  one  another,  the  tendin- 
ous fibres  of  one  side  crossing  and  intersecting  those  of  the  opposite  side. 
From  its  white  appearance,  rendered  more  conspicuous  by  the  dark 
color  of  the  straight  muscle  being  seen  through  the  aponeurosis  on  each 
side,  it  is  named  the  linea  alba.5  This  is  wide  above  but  narrow  below, 
and  separates  the  straight  muscles.  Near  its  middle  the  umbilicus  ap- 
pears as  a  fibrous  cicatrix. 

The  aponeuroses  of  the  broad  muscles  commence  nearly  in  the  same 
position,  corresponding  with  the  outer  border  of  the  straight  muscles. 
This  position  also  appears  as  a  white  line,  in  contrast  with  the  fleshy 
bellies  on  each  side,  and  is  named,  from  its  curving  inwardly  as  it  ap- 
proaches the  pubis,  the  semilunar  line.6 

Crossing  from  the  semilunar  to  the  median  line,  the  tendinous  intersec- 
tions of  the  straight  muscle  are  seen  through  the  aponeurosis  investing 
the  latter,  and  are  named,  from  their  course,  the  transverse  lines.7  One 
of  these  exists  nearly  opposite  the  lower  end  of  the  sternum,  a  second 
about  half  the  distance  from  this  to  the  umbilicus,  a  third  nearly  on  a 
level  with  the  latter,  and  usually  an  imperfect  one  half  way  between  the 
umbilicus  and  pubis.  They  intimately  adhere  to  the  aponeurosis  in  front 

1  Linea    semicircularis ;     linea     Dou-  *  M.  pyramidalis  abdominis ;   m.  pu- 
glasii ;  plica  semilunaris  Douglasii.  bio-umbilicalis  ;  m.  Fallopii ;  m.  succen- 

2  Sitzungsberichte  der   K.  Akad.  der  turiatus*;  m.  auxiliarius. 
Wissenschaften.   Wien,  1858,  page  259.  *  L.  centralis ;  1.  candidula. 

3  Cavum  prseperitoneale ;  c.  p.  Retzii;  6  L.  semilunaris. 
porta  vesicae ;  p.  v.  Retzii.  *  L.  transversse. 


218  THE    MUSCULAR   SYSTEM. 

of  the  straight  muscle,  and,  in  powerfully  muscular  men,  together  with 
the  median  and  semilunar  lines,  indicate  the  position  of  the  intervening 
fleshy  bellies,  even  through  the  tegumentary  covering  of  the  abdomen. 

The  Quad'rate  Lum'bar  muscle1  is  situated  at  the  side  of  the  lumbar 
vertebrae,  and  is  inclosed  in  a  sheath  formed  by  the  lumbar  fascia.  It 
arises  tendinously  from  the  crest  of  the  ilium  back  of  its  middle,  and 
ascends  to  be  inserted  into  the  last  rib  and  the  transverse  processes  of 
the  lumbar  vertebrae,  except  the  last  one. 

The  muscles  of  the  abdomen  support  and  compress  the  viscera  of  its 
cavity.  By  depressing  the  ribs  and  elevating  the  abdominal  viscera, 
they  antagonize  the  action  of  the  diaphragm,  and  thus  become  the  prin- 
cipal muscles  in  expiration.  They  act  also  in  the  expulsion  of  the  con- 
tents of  the  bowels  and  urinary  bladder,  in  the  birth  of  the  child,  in 
vomiting,  etc. 

THE  LUMBAR  FASCIA. 

The  Lum/bar  fas'cia2  consists  of  two  fibrous  layers  inclosing  the 
quadrate  lumbar  muscle,  and  forming  part  of  the  origin  of  the  internal 
oblique,  transverse,  and  latissimus  muscles.  The  anterior  layer  is  at- 
tached to  the  front  of  the  roots  of  the  transverse  processes  of  the  lumbar 
vertebrae,  the  crest  of  the  ilium,  and  the  last  rib ;  in  which  latter  position 
its  thickened  margin  constitutes  the  external  arc'uate  ligament.3  The 
posterior  layer,  thicker  and  more  aponeurotic  than  the  other,  is  attached 
to  the  ends  of  the  transverse  processes  of  the  lumbar  vertebrae,  the  crest 
of  the  ilium,  and  the  last  rib.  It  separates  the  quadrate  lumbar  muscle 
from  the  dorsal  extensor,  and  is  joined  at  the  outer  border  of  the  former 
by  the  anterior  layer,  in  which  position  it  gives  origin  to  the  muscles  above 
mentioned. 

THE  TRANSVERSE  FASCIA  OF  THE  ABDOMEN. 

The  Transverse  fascia4  of  the  abdomen  is  a  thin,  fibrous  membrane 
investing  the  inner  surface  of  the  transverse  muscles,  and  attaching  them 
to  the  peritoneum.  It  is  strongest  in  the  inguinal  region,  and  in  this 
position  is  important  in  its  relations  with  hernia.  It  invests  the  straight 
muscle  where  its  sheath  is  incomplete,  and  closely  adheres  to  the  lunated 
margin  of  the  latter,  as  it  does  also  to  the  body  and  pectineal  line  of  the 
pubis,  behind  the  tendon  of  the  straight  muscle  and  the  conjoined  tendon 

1  M.  quadratus  lumborum,  or  dorsi ;  2  F.  lumborum. 

m.  lumbaris  externus;    m  flectans   par  3  L.  arcuatura  externum. 

lumborum;     m.    ilio-costalis ;     m.    ilio-  4  F.  transversa;    f.  transversnlis ;    f. 

lumbo-costalis.  Coopcri;  f.  endogastrica. 


THE   MUSCULAR   SYSTEM. 


219 


of  the  internal  oblique  and  transverse  muscles.  Traced  upward,  it  becomes 
thinner,  and  is  continuous  with  the  fibrous  attachment  of  the  peritoneum 
to  the  diaphragm.  Traced  toward  the  loins,  it  becomes  thinner  and  looser 
in  texture.  It  tightly  adheres  to  the  crest  of  the  ilium  and  Poupart's 
ligament,  and  from  these  positions  is  continuous  with  the  iliac  fascia. 

Half  way  between  the  anterior  superior  spinous  process  of  the  ilium 
and  the  symphysis  of  the  pubis,  just  above  Poupart's  ligament,  the  trans- 
verse fascia  is  prolonged  downward  and  inward  as  a  sheath1  to  the  sper- 
matic cord.  The  entrance  of  this  prolongation,  viewed  as  an  orifice,  is 
named  the  internal  abdom'inal  ring,  the  commencement  of  the  inguinal 
canal. 

THE   INGUINAL  CANAL. 

The  In'guinal  canal2  is  the  space  in  the  lower  part  of  the  abdominal 
walls  whicfh  gives  passage  to  the  spermatic  cord  of  the  male,  and  the 
round  ligament  of  the  uterus  in  the  female.  It  is  narrower  in  the  latter, 
in  accordance  with  the  smaller  size  of  the  round  ligament  than  the 

spermatic  cord. 

FIG.  158. 

VIEW    OF    THE    INGUINAL    CAXAL.      1,  por- 

tion  of  the  fleshy  belly  of  the  external  ob- 
lique muscle;  2,  its  aponeurosis;  3,  por- 
tion of  the  latter  raised  up,  exposing  the 
inguinal  canal;  4,  linea  alba;  5,  insertion 
of  the  aponeurosis  of  the  external  oblique 
into  the  body  of  the  pubis;  6,  its  insertion 
into  the  spine  of  the  pubis,  named  Pou- 
part's ligament;  7,  division  of  the  fibres 
of  the  aponeurosis  crossed  by  transverse 
fibres;  8,  external  abdominal  ring,  the  ter- 
mination of  the  inguinal  canal ;  9,  anterior 
superior  spinous  process,  the  origin  of 
Poupart's  ligament ;  10,  arching  lower  bor- 
der of  the  internal  oblique  and  transverse 
muscles;  11,  conjoined  tendon  of  the  latter 
muscles ;  12,  fibres  of  the  cremaster  muscle 
descending  on  the  spermatic  cord  from  the 
edges  of  the  muscles  just  named ;  13,  rests 
on  the  transverse  fascia;  to  its  right  are 
the  epigastric  vessels  crossing  the  course 
of  the  inguinal  canal;  14,  iliac  portion  of 
the  femoral  fascia ;  15,  pubic  portion ;  16, 
falciform  proces's;  17,  saphenous  opening; 
18,  saphenous  vein  joining  the  femoral  vein  through  the  saphenous  opening;  19,  the  femoral  artery  and 
vein  exposed  by  raising  the  portion  of  fascia  which  forms  the  falciform  process;  20,  suspensory  ligament 
of  the  penis. 

The  canal  is  about  an  inch  and  a  half  long ;  its  upper  extremity  being 
the  internal  abdominal  ring,3  and  its  lower  extremity  the  external 


1  Infundibuliform  fascia ;  fascia  sper- 
matica  interna,  or  propria. 


2  Canalis  inguinalis ;  spermatic  canal. 

3  Apertura  interna;  a.  abdominalis. 


220  THE   MUSCULAR  SYSTEM. 

abdom/inal  ring.1  In  front  it  is  bounded  by  the  aponeurosis  of  the 
external  oblique  muscle,  behind  by  the  transverse  fascia  and  conjoined 
tendon  of  the  internal  oblique  and  transverse  muscles,  above  by  the 
arching  borders  of  the  latter  muscles,  and  below  by  Poupart's  ligament. 

The  middle  of  the  inguinal  canal  is  crossed  behind  by  the  epigastric 
blood-vessels,  which  pursue  their  course,  involved  in  the  structure  of  the 
transverse  fascia,  from  the  external  iliac  blood  vessels,  upward  and  in- 
ward toward  the  umbilicus. 

The  interior  surface  of  the  abdominal  wall,  in  the  inguinal  region, 
presents  a  slight  fold  of  peritoneum  pursuing  the  same  course  as  the  epi- 
gastric blood-vessels,  and  hence  called  the  epigas'tric  fold.2  The  fold 
divides  the  inguinal  region  into  two  shallow  depressions  named  the 
internal  and  external  in'gninal  fossae.3 

The  deeper  part  of  the  internal  in'guinal  fossa4  corresponds  with  the 
position  of  the  external  abdominal  ring,  and  is  the  point  at  which  direct 
inguinal  hernia  occurs. 

The  deeper  part  of  the  external  hi/gninal  fossa  corresponds  with  the 
position  of  the  internal  abdominal  ring,  into  which  the  peritoneum  is 
sometimes  prolonged,  especially  in  the  female,  as  a  small  funnel-like  pit;5 
and  at  this  point  oblique  inguinal  hernia  has  its  commencement. 

REMARKS  ON  INGUINAL  HERNIA. 

The  protrusion  of  any  portion  of  the  contents  of  the  abdomen  through 
an  opening  in  its  parietes  is  called  a  her'nia ;  the  varieties  of  which  are 
named  from  the  particular  positions  of  their  occurrence,  and  thus  we  have 
umbilical  hernia,  inguinal  hernia,  femoral  hernia,  and  others.  The  pro- 
truding part  pushes  before  it  the  membranous  structures  it  meets  in  its 
passage,  and  these  furnish  coverings  to  the  hernia.  The  peritoneum, 
which  is  the  membrane  first  protruded,  forms  the  so-called  her'nial  sac. 

An  inguinal  hernia  may  occur  either  from  the  internal  or  the  external 
inguinal  fossa.  Most  frequent  from  the  latter  position,  it  follows  the 
course  of  the  inguinal  canal,  and  emerges  at  the  external  abdominal  ring, 
anfl  receives  the  name  of  oblique  in'guinal  her'nia,  In  this  variety  the 
hernial  sac  has  for  its  coverings,  in  the  order  of  their  protrusion :  first, 
a  membrane,  more  or  less  distinct,  formed  by  the  association  of  the  trans- 
verse and  intercolumnar  fascia,  including  the  fibres  of  the  cremaster 
muscle ;  second,  the  superficial  fascia ;  and  third,  the  skin. 

1  Annulus  inguinalis ;  apertura  externa.  4  Triangle  of  Hesselbach. 

2  Plica  epigastrica.  5  Canal  of  Nuck. 

3  Foveae  inguinales. 


THE  MUSCULAR  SYSTEM.  221 

The  protrusion  of  a  hernia  directly  through  the  external  abdominal 
ring  occurs  from  the  internal  inguinal  fossa,  and  receives  the  name  of 
direct  in/guinal  hernia.1  The  coverings  of  the  hernial  sac  in  this  variety, 
in  the  order  of  protrusion,  are:  first,  a  membranous  investment,  derived 
from  the  transverse  fascia  and  the  intercolumnar  fascia,  including  some 
loose  fibres  of  the  conjoined  tendon ;  second,  the  superficial  fascia ;  and, 
third,  the  skin.  If  the  protrusion  occurs  through  a  separation  or  interval 
of  the  fibres  of  the  conjoined  tendon,  this  structure  would  not  contribute 
to  form  the  first  covering  of  the  hernial  sac. 

In  consequence  of  the  comparative  narrowness  of  the  inguinal  canal 
and  smallness  of  the  abdominal  rings,  inguinal  hernia  is  of  rare'  occur- 
rence in  the  female. 

In  oblique  inguinal  hernia,  the  excretory  duct  of  the  testicle  and  ves- 
sels of  the  spermatic  cord  and  the  epigastric  blood-vessels  lie  at  the  inner 
side  of  the  neck  of  the  hernia ;  but  in  direct  inguinal  hernia,  the  sper- 
matic cord  and  epigastric  vessels  are  at  the  outer  side. 


THE  DIAPHRAGM. 

The  Di'aphragm2  is  a  muscular  partition  separating  the  thorax  and 
abdomen.  Its  under  or  abdominal  surface  is  deeply  vaulted,  and  is 
invested  by  the  peritoneum  ;  its  upper  surface  is  convex,  and  is  covered 
by  the  two  pleura3  and  the  pericardium.  Its  centre  rises  to  a  level  with 
the  fifth  costal  cartilages ;  and  on  the  right  side,  apparently  to  accom- 
modate the  liver,  it  rises  higher  than  upon  the  left. 

The  origin  of  the  diaphragm  is  from  the  inferior  margin  of  the  thorax 
as  constituted  by  the  end  of  the  sternum  and  the  lower  six  ribs,  from  the 
arcuate  ligaments,  and  from  the  bodies  of  the  upper  four  lumbar  verte- 
bra. From  this  extensive  circle  the  fleshy  fasciculi  ascend  and  converge 
to  a  central  tendon. 

The  origin  from  the  ribs  is  by  fleshy  serrations  included  between  similar 
processes  of  the  transverse  muscles  of  the  abdomen. 

The  arc'uate  ligaments3  are  thin  and  narrow  fibrous  arches,  of  which 
the  inner  one  extends  over  the  upper  extremity  of  the  psoas  muscle  from 
the  body  of  the  first  lumbar  vertebra  to  its  transverse  process ;  the 
outer  one  forms  the  upper  edge  of  the  anterior  layer  of  the  lumbar  fascia, 

1  Internal  inguinal  hernia ;  ventro-in-  phrenes  ;    praecordia ;   praecinctus ;  suc- 
guinal  hernia.  Centura;     muse,    succinctus;      septum 

2  Diaphragma  ;    musculus   phrenicus  ;  transversum ;  respiratoriura  ventris. 
midriff ;  diaphraxis  ;  disseptum  ;  discre-  3  Ligamenta  arcuata. 

torium ;  hypozoma;  perizoma;  diazomo; 


900 


THE    MUSCULAR   SYSTEM. 


FIG.  159. 


extended  from  the  transverse  process  of  the  first  lumbar  vertebra  to  the 

end  of  the  last  rib. 

The  portions  of  the  diaphragm  proceeding  from  the  lumbar  vertebra? 

are  named  its  crura.1  The 
right  crus  is  the  larger, 
and  arises  tendinously 
from  the  bodies  and  in- 
tervening fibro-cartilages 
of  the  upper  four  lumbar 
vertebraB ;  the  left  cms 
arises  in  the  same  manner 
from  the  upper  three. 

The  central  tendon2  of 
the  diaphragm  is  a  broad 
aponeurosis,  composed  of 
converging  and  inter- 
woven fibrous  bands,  and 
is  entirely  surrounded  by 
the  fleshy  part  of  the 
muscle.  It  is  usually  de- 

TNFERIOR  VIEW  OF  THE  DIAPHRAGM.  1,  2,  3,  the  three  lobes  of  the     scribed  as  SOmewhlt  heart 
central  tendon,  surrounded  by  the  fleshy  fasciculi  derived  from 

the  inferior  margin  of  the  thorax,  the  crura,  4,  5,  and  the  arcuate  Shaped,  With  the  notch  di- 
ligaments,  6,  7  ;  8,  aortic  orifice;  9,  oesophageal  orifice ;  10,  quad-  rected  backward  Or  more 
rate  foramen ;  11,  psoas  muscle ;  12,  quadrate  lumbar  muscle. 

correctly  as  trilobed,  one 
lobe  being  directed  forward,  and  one  backward  on  each  side. 

Three  important  orifices  exist  in  the  diaphragm  for  the  passage  of  the 
aorta,  oesophagus,  and  inferior  cava. 

The  aort'ic  orifice3  is  formed  between  the  crura  of  the  diaphragm  in 
front  of  the  first  lumbar  vertebra.  The  tendons  of  origin  of  the  crura 
meet  behind  the  aorta,  and  conjoin  in  a  narrow  arch  in  front  of  it,  so  that 
the  vessel  is  inclosed  by  fibrous  structure  and  is  not  liable  to  constriction 
from  the  action  of  the  fleshy  portion  of  the  muscle.  Besides  the  aorta, 
the  thoracic  duct  passes  through  the  aortic  orifice  of  the  diaphragm. 

The  cesophage'al  orifice4  is  an  elliptical  opening,  situated  above  and  a 
little  to  the  left  of  the  aortic  orifice,  in  the  muscular  structure  of  the 
diaphragm.  In  the  ascent  of  the  crura  of  the  latter,  their  fleshy  fasci- 
culi cross  in  front  of  the  aortic  orifice,  and  then,  proceeding  upward  to 


1  Pillars ;  columns ;  pars  lumbalis. 

2  Centrum  tendineum,  phrenicum,  or 
nerveum;     pars   tendinea;    tendo    dia- 
phragmatis;  speculum  Helmontii ;  cordi- 
form  tendon;  phrenic  centre. 


3  Hiatus  aorticus;  semicirculus  ex- 
culptus. 

*  (Esophageal  aperture  or  foramen ; 
for.  03sophageum. 


THE  MUSCULAR  SYSTEM.  223 

reach  the  central  tendon,  leave  between  them  the  cesophageal  orifice. 
The  fleshy  constitution  of  the  borders  of  this  aperture  adapts  it  to  act 
the  part  of  a  sphincter  muscle  to  the  oesophagus. 

The  remaining  orifice,  which  transmits  the  ascending  cava,  is  situated 
in  the  central  tendon,  to  the  right  of  its  middle.  Formed  between  the 
crossing  fibrous  bands  of  the  tendon,  it  is  somewhat  square,  with  rounded 
angles,  and  hence  is  named  the  quad/rate  foramen.1 

Besides  the  orifices  described,  the  crura  of  the  diaphragm  are  pierced 
by  the  great  sympathetic  nerves  and  azygos  veins. 

The  diaphragm  is  the  most  important  of  the  respiratory  muscles.  In 
contracting  it  descends,  and  thus  increases  the  capacity  of  the  chest,  and 
produces  inspiration.  The  abdominal  muscles  are  the  chief  antagonists 
to  its  action.  It  performs  an  important  part  in  coughing,  laughing, 
sneezing,  yawning,  sighing,  crying,  sobbing,  hiccoughing,  singing,  vomit- 
ing, the  voiding  of  the  excrement,  and  the  expulsion  of  the  foetus. 

MUSCLES   OF  THE  PERINEUM. 

See  the  article  Perineum,  after  the  account  of  the  generative  appa- 
ratus. 

THE   UPPER  EXTREMITY. 

The  Tipper  Extremity  commences  with  the  prominence  of  the  shoulder, 
beneath  which  is  the  axil'la2  or  armpit,  bounded  in  front  and  behind  by 
thick  borders,  the  ax'illary  folds.  The  arm3  is  cylindrical,  and  terminates 
in  the  bend  of  the  arm  or  elbow,  which  is  bounded  on  each  side  by  the 
prominences  of  the  condyles,  and  behind  by  the  prominence  of  the  ole- 
cranon,  the  elbow.  The  forearm*  is  club  shaped,  and  compressed  from 
within  outwardly.  Its  prominent  inner  portion  above  is  produced  by 
the  flexor  and  pronator  muscles ;  its  corresponding  outer  portion,  by  the 
extensor  and  supinator  muscles.  The  back  or  dorsal  surface  of  the 
hand  is  broad  and  convex,  and  presents  no  indication  of  the  separation 
existing  between  the  carpus  and  metacarpus.  The  palm  or  palmar  sur- 
face exhibits  the  hollow  of  the  hand,  bounded  above  by  the  prominence 
of  the  carpus  or  wrist,  and  at  the  sides  by  the  ball  of  the  thumb5  and 
little  finger.5 

The  wrist  joint,  or  radio-carpal  articulation,  is  indicated  in  front  by 
transverse  furrows  of  the  skin.  The  metacarpo-phalangial  articulations 
are  indicated  by  the  knuckles  behind,  and  transverse  furrows  at  the  ante- 

1  F.  quadratum;  f.  venosum.  3  Brachium. 

2  Assella;     fovea     axillaris;     cordis  *  Antibrachium ;  pars  inferior  brachii ; 
emunctorium;    hypomin ;    male;     mas-       cubitus. 

chalis.  5  Thenar  and  liypothenar  eminences. 


224  THE   MUSCULAR  SYSTEM. 

rior  third  of  the  palm.  The  phalangial  articulations  are  likewise  indi- 
cated by  knuckles,  and  by  transverse  furrows  of  the  skin  before  and 
behind. 

The  fingers,  as  previously  mentioned,  are  named  in  succession,  the 
thumb,1  the  index  or  fore  finger,2  the  middle,3  the  ring,4  and  the  little 
fingers.5 

The  skin  of  the  upper  extremity  is  moderately  thick  and  dense  exter- 
nally or  posteriorly ;  thin  and  extensible  internally  or  anteriorly.  It  is 
readily  movable  to  and  fro  on  the  parts  beneath,  except  in  the  palm  of 
the  hand. 

FASCIAE  OF  THE  UPPER  EXTREMITY. 

The  Superficial  fascia  of  the  upper  extremity  is  a  rather  loose  layer 
of  areolar  tissue  connecting  the  skin  with  the  deep  fascia  and  with  the 
various  subcutaneous  prominences  and  ridges  of  the  bones.  Its  super- 
ficial portion  contains  more  or  less  fat,  the  superficial  venous  trunks,  and 
the  cutaneous  nerves  in  their  course  to  the  skin.  Accumulation  of  fat 
involves  the  veins  just  mentioned,  and,  occupying  the  angular  intervals 
of  the  different  groups  of  muscles,  gives  the  characteristic  rounded  form 
to  the  limbs  of  young  children,  well-developed  women,  and  fat  men. 
The  deeper  portion  of  the  fascia  is  more  membranous  in  character, 
and  defines  the  fatty  layer  from  the  parts  beneath.  Upon  the  acromion 
and  olecranon  the  superficial  fascia  is  always  devoid  of  fat;  and  in  the 
latter  position  it  contains  an  irregular  synovial  bursa,  devoid  of  an 
epithelium. 

Approaching  the  wrist  and  hand,  the  fatty  layer  of  the  superficial 
fascia  decreases,  but  is  never  absent  from  the  palm  of  the  hand,  where  it 
is  intimately  blended  with  the  under  surface  of  the  skin. 

The  Deep  fascia6  of  the  upper  extremity  is  a  continuation  of  the  thin 
membrane  investing  the  pectoral,  trapezius,  latissimus,  and  great  serrated 
muscles.  Adhering  to  the  clavicle,  acromion,  and  spine  of  the  scapula, 
it  gives  the  deltoid  muscle  a  thin  covering,  and  extends  downward  upon 
the  arm.  A  portion  invests  the  subscapular  and  terete  muscles ;  but 
stronger  portions  cover  the  supra-  and  infra-spinous  muscles,  adhering 
intimately  to  the  borders  of  the  fossae  whence  the  muscles  arise.  It 
incloses  the  axilla  by  crossing  from  the  pectoral  to  the  latissimus  muscle, 
and  it  is  intimately  associated  with  the  sheath  of  the  axillary  and  brachial 
vessels  and  nerves.  It  is  thin  upon  the  inner  part  of  the  arm,  is  thicker 
on  the  back  part,  and  increases  in  strength  as  it  approaches  the  elbow, 

1  Pollex.  *  D.  annularis. 

2  Digitus  indicis.  5  D.  minimus. 

3  D.  medius.  6  Brachial  and  antebrachial  fascia. 


THE  MUSCULAR  SYSTEM.  225 

where  it  adheres  to  the  olecranon,  the  condyles,  and  the  condyloid 
ridges, — the  attachments  to  the  latter  constituting  intermuscular  parti- 
tions. It  receives  offsets  from  the  tendons  of  insertion  of  the  pectoral, 
latissimus,  and  triceps  muscles,  and  also  gives  origin  to  some  of  the  fleshy 
fasciculi  of  the  latter. 

In  the  forearm  the  deep  fascia  has  an  aponeurotic  appearance;  is 
bluish  white,  and  shining,  and  is  composed  of  transverse  fibres  conjoined 
by  others  running  longitudinally.  From  the  tendon  of  the  biceps  it 
receives  a  conspicuous  offset,  which  expands  upon  the  muscles  arising 
from  the  internal  condyle,  and  separates  the  median  basilic  vein  from  the 
brachial  vessels  and  median  nerve.  Extensions  of  the  fascia  inwardly 
l>etween  the  muscles  constitute  intermuscular  partitions,  which,  together 
with  the  inner  surface  of  the  fascia  afford  origin  to  many  of  the  fleshy 
fasciculi  of  the  muscles. 

At  the  wrist,  by  strong  accessions  of  transverse  fibres,  the  deep  fascia 
forms  the  annular  ligaments,  which  serve  to  maintain  the  position  of  the 
flexor  tendons  in  their  course  to  the  hand. 

The  Anterior  an'nular  ligament1  is  a  strong,  thick,  and  wide  band 
extended  from  the  inner  to  the  outer  side  of  the  front  of  the  carpus, 
being  attached  by  one  extremity  to  the  pisiform  and  unciform  bones, 
by  the  other  to  the  trapezial  and  scaphoid  bones.  With  the  concavity 
of  the  carpus  it  forms  a  canal  for  the  passage  of  the  flexor  tendons  and 
median  nerve  to  the  palm  of  the  hand. 

The  Posterior  an'nular  ligament,2  less  distinct  and  strong  than  the 
preceding,  is  a  wide  band  of  oblique  fibres  extended  from  the  outer  border 
of  the  lower  end  of  the  radius  to  the  inner  side  of  the  ulna  and  the  pisiform 
bone.  As  it  crosses  the  radius  and  ulna,  it  tightly  adheres  to  the  parallel 
ridges  at  their  lower  ends,  thus  converting  the  intermediate  grooves  into 
canals,  through  which  the  extensor  tendons  pass  to  the  back  of  the  hand. 

The  deep  fascia  on  the  back  of  the  hand  extends  as  a  thin  layer  from 
the  ligament  just  described  to  the  fingers,  and  is  intimately  connected  with 
the  extensor  tendons  beneath.  The  palmar  fascia3  extends  from  the 
annular  ligament,  as  a  thin  investment  to  the  ball  of  the  thumb  and 
little  finger.  The  middle  portion  is  a  strong,  triangular  aponeurosis, 
composed  of  fibres  diverging  from  the  annular  ligament  and  connected 
by  transverse  fibres.  Its  apex  partly  receives  the  insertion  of  the  tendon 
of  the  long  palmar  muscle ;  its  base  divides  into  four  processes,  each  of 
which  subdivides  upon  the  flexor  tendons  as  these  diverge  to  the  fingers, 

1  L.  annulare,  or  transversum  anterius ;  1.  commune,  or  carpi  volare. 

2  L.  annulare,  or  transversum  posterius ;  1.  commune,  or  carpi  dorsale. 

3  Aponeurosis  palmaris. 

15 


226 


THE    MUSCULAR  SYSTEM. 


FIG.  160. 


and  the  subdivisions  are  attached  to  the  vaginal  ligaments  and  those  of 
the  metacarpo-phalangial  articulations. 

The  Vag'inal  ligaments1  are  fibrous  sheaths,  inclosing  the  flexor  ten- 
dons, in  front  of  the  phalanges,  with  the  lateral  edges  of  which  they  are 
firmly  attached.  They  are  composed  of  transverse  and  obliquely  cross- 
ing bands,  thick  and  strong  in  front  of  the  phalanges,  but  thin  upon  the 
articulations,  so  as  not  to  impede  the  movement  of  the  latter. 

The  tendons  of  the  flexor  and  extensor  muscles,  as  they  pass  through 
the  canals  formed  by  the  annular  and  vaginal  ligaments,  are  invested 
with  synovial  sheaths.2 

MUSCLES  OF  THE  SHOULDER. 

The  Supra-spi'nous  muscle3  arises  from  the  corresponding  fossa  of  the 

scapula  and  from  an  in- 
vesting aponeurosis.  Its 
fleshy  fasciculi  converge 
to  a  tendon  which  pro- 
ceeds beneath  the  acro- 
mion,  adheres  to  the  cap- 
sular  ligament  of  the 
shoulder  joint,  and  is  in- 
serted into  the  upper  part 
of  the  greater  tuberosity 
of  the  humerus. 

The    Infra-spi'nous 

MUSCLES  ox  THE  BACK  OF  THE  SCAFCLA.  1,  supra-spinous  muscle;  ™lSCle4  aris6S  fr°m  the 
2,  infra-spinous  muscle;  3,  lesser  terete  muscle  ;  4,  greater  terete  Corresponding  foSSa  of  the 

scapula  and  converges  to 

a  tendon,  which,  proceeding  over  the  capsular  ligament  of  the  shoulder 
joint,  is  inserted  into  the  middle  part  of  the  greater  tuberosity  of  the 
humerus. 

The  Lesser  Te'rete  muscle5  arises  from  the  upper  part  of  the  outer 
border  of  the  scapula,  and,  in  contact  with  the  preceding  muscle,  fre- 
quently more  or  less  conjoined  with  it,  ascends  to  be  inserted  into  the 
lower  part  of  the  greater  tuberosity  of  the  humerus. 

The  Subscap'ular  muscle6  arises  by  broad  fasciculi  from  the  corre- 


1  L.   vaginalia ;    vaginal  and  crucial 
ligaments. 

2  Vaginae  synoviales. 

3  M.  supra- spinatus  ;  m.  supra-scapu- 
laris ;  m.  superscapularis  superior. 


*  M.  infra-spinatus  ; 
laris  inferior. 
6  M.  teres  minor. 
6  M.  subscapularis. 


m.  superscapu- 


THE   MUSCULAR  SYSTEM. 


227 


FIG 


spending  fossa  of  the  scapula,  and  converges  to  a  strong  tendon,  which 

passes  in  front  of  the  shoulder  joint,  and  is  inserted  into  the  lesser  tu- 

berosity  of  the  humerus. 

It  lies  upon  the  great  ser- 

rated muscle,  from  which 

it  is  separated  by  a  thin 

fascia1  and  some  loose  are- 

olar  tissue  extending  from 

the   axilla.     Between  its 

tendon  and  the  neck  of  the 

scapula  a  synovial  bursa 

is  interposed. 

The  subscapular  muscle 

MUSCLES  ON  THE  FROXT  OF  THE  SCAPUH.    1,  subscapular  muscle: 

rotates  the  arm   inwardly,      2,  greater  terete  muscle  ;  3,  upper  part  of  the  triceps  extensor;  4. 
and      the       SUpra-SpinOUS,      supra-spinous  muscle. 

infra-spinous,  and  lesser  terete  muscles  rotate  it  outwardly.  The  tendons 
of  these  four  muscles,  as  they  approach  their  insertion,  partially  surround 
the  shoulder  joint,  form  an  intimate 
connection  with  its  capsular  liga- 
ment, and  contribute  very  greatly 
to  its  strength. 

MUSCLES   OF  THE  AKM. 

The  Greater  Te'rete  muscle2 
forms  part  of  the  posterior  fold  of 
the  axilla.  It  arises  from  the  lower 
part  of  the  inferior  border  and  angle 
of  the  scapula,  ascends  beneath  the 
latissimus  muscle,  and  terminates 
in  a  broad  tendon,  which  is  inserted 
into  the  posterior  bicipital  ridge  of 
the  humerus,  in  contact  with  the  ten- 
don of  the  latissimus.  The  long  head 
of  the  triceps  separates  the  greater 
from  the  lesser  terete  muscle. 

The  greater  terete  muscle  assists  the  latissimus  in  its  action. 


FIG.  162. 


THE  DELTOID  MUSCLE.  1,  its  insertion;  2,  its  ori- 
gin from  the  clavicle;  3,  origin  from  the  spine  and 
acromion  of  the  scapula. 


The  Del'toid  muscle3  forms  the  convex  prominence  of  the  shoulder. 


1  Fascia  subscapularis. 

2  M.  teres  major;    m.  scapulo-humer- 
alis. 


3  M.  deltoideus ;  m.  deltiformis ;  m. 
supra-acromio-humeralis;  m.  attollens 
humeri. 


228 


THE   MUSCULAR  SYSTEM. 


It  arises,  partially  tendinous  and  fleshy,  from  the  outer  third  of  the 
clavicle,  the  acromion,  and  the  lower  margin  of  the  spine  of  the  scapula, 
and  converges  to  be  inserted,  partially  tendinous  and  fleshy, -into  the 
roughness  near  the  middle  of  the  outer  part  of  the  humerus.  The  muscle 
has  coarse,  fleshy  fasciculi,  intermingled  with  tendinous  fibres. 

The  deltoid  muscle  is  the  elevator  of  the  arm,  and  may  raise  the  limb 
to  a  vertical  position.  It  is  also  an  efficient  aid  in  drawing  the  arm 
backward  or  forward,  and  greatly  contributes  to  the  strength  of  the 
shoulder  joint. 


FTG.  103. 


The  Cor'aco-bra'chial  muscle,1  situated  along  the  upper  and  inner 
part  of  the  arm,  arises  tendinously,  in  common 
with  the  short  head  of  the  biceps  muscle,  from 
the  coracoid  process  of  the  scapula,  and  pro- 
ceeds downward  to  be  inserted  about  the  middle 
of  the  inner  side  of  the  humerus.  It  is  usually 
perforated  by  the  external  cutaneous  nerve  in 
its  course  to  the  outer  part  of  the  arm. 

The  Bi'ceps  Flex'or2  is  situated  in  front  of 
the  arm,  extending  from  the  scapula  to  the 
forearm.  As  the  name  indicates,  it  arises  by 
two  heads,  of  which  the  internal  or  short  one 
is  derived,  in  common  with  the  preceding  mus- 
cle, from  the  coracoid  process  of  the  scapula, 
The  long  head  arises  from  the  summit  of  the 
glenoid  cavity,  by  a  narrow  tendon  which  passes 
through  the  upper  part  of  the  shoulder  joint, 
insheathed  by  the  synovial  membrane,  and  de- 
scends along  the  bicipital  groove  of  the  humerus. 
The  two  heads  conjoin  and  form  a  thick,  fleshy 
belly,  terminating  in  a  strong  tendon,  which 
penetrates  between  the  supinator  and  flexor 
muscles  of  the  forearm,  to  be  inserted  into  the 
back  part  of  the  tuberosity  of  the  radius. 

Between  the  tendon  of  insertion  and  the 
fore  part  of  the  latter  tuberosity,  a  synovial 
bursa  is  interposed ;  and  from  the  commence- 
ment of  the  same  tendon  an  aponeurotic  process 
of  the  forearm  just  below  the  internal  condyle. 


MUSCLES  OF  THE  FORE  PART  OF  THE 
ARM.  1,  coracoid  process  of  the 
Hcapula:  2,  coraco-clavicular  liga- 
ment ;  3,  coraco-acromial  ligament : 
4,  subscapular  muscle;  5,  greater 
terete  muscle;  6,  coraco-brachial 
muscle;  7,  biceps  flexor;  8,  its  in- 
sertion into  the  tuberosity  of  the 
radius;  9,  brachial  muscle;  10,  tri- 
ceps extensor. 

is  given  off  to  the  fascia 


1  M.  coraco-brachialis,  or  humeralis ;  m.  perforatus,  or  m.  p.  Casserii. 

2  M.  biceps  flexor  cubiti ;  m.  biceps  brachialis ;  m.  biceps  interims ;  m.  coraco- 
radialis;  m.  scapulo-radialis;  the  biceps. 


THE  MUSCULAR  SYSTEM. 


229 


FIG.  164. 


The  Bra'chial  muscle1  lies  beneath  the  biceps  muscle  at  the  lower 
part  of  the  arm,  and  covers  the  front  of  the  elbow  joint.  It  arises  from 
the  humerus  each  side  of  the  insertion  of  the  deltoid  muscle  and  from  the 
surface  of  the  bone  below,  and  converges  to  be  inserted  tendinously  into 
the  fore  part  of  the  coracoid  process  of  the  ulna. 

The  coraco-brachial  muscle  draws  the  arm  inwardly.  If  the  hand  is 
prone,  the  biceps  supinates  it  by  rotating  the 
radius  outwardly,  and  if  the  action  of  the 
muscle  continues,  the  forearm  is  flexed.  The 
brachial  muscle  is  also  a  flexor  of  the  forearm, 
and  from  its  position  greatly  contributes  to 
the  strength  of  the  elbow  joint. 

The  Tri'ceps  Extensor2  forms  the  whole  of 
the  fleshy  mass  on  the  posterior  part  of  the 
arm,  and,  as  the  name  implies,  arises  by  three 
heads. 

The  external  head3  arises  from  the  humerus, 
below  the  greater  tuberosity  ;  the  short  head4 
arises  from  the  humerus,  below  the  greater  te- 
rete muscle ;  and  the  long  head5  arises  from 
the  border  of  the  scapula,  below  the  glenoid 
cavity.  The  three  heads  conjoin  in  one  fleshy 
belly,  which  in  its  descent  receives  a  constant 
accession  of  fasciculi  from  the  surface  of  the 
humerus,  and  terminates  in  a  strong  aponeur- 
otic  band  facing  the  muscle  posteriorly  and  in- 
serted into  the  olecranon  process  of  the  ulna. 
Between  the  tendinous  insertion  and  the  top  of  ON  THE  BACK  OF  THE  RIGHT  ARM.  i, 
the  process,  a  synovia!  bursa  is  introduced.  Z^J&Jg* 

This  mUSCle  is  the  extensor  Of  the  forearm.         cle  into  the  olecranon  of  the  ulna; 

5,  radius ;  6,  capsular  ligament  of 

The  Ancone'us  muscle6  appears  to  be  a  con-    the  8houlder  joint' 
tinuation  of  the  triceps  below  the  outer  part  of  the  elbow.     It  arises 


ViEAV  OF  THE  TRICEPS   EXTENSOR, 


1  M.  brachialis    anticus  ;    m.  b.  inter- 
ims ;    m.  b.  humero-cubitalis ;    m.  bra- 
chiaeus  ;  anterior  brachial  muscle. 

2  M  triceps  extensor  cubiti,  or  brachii; 
m.  triceps  brachialis. 

3  Caput   externum;    anconsens   exter- 
nus  ;  vastus  externus ;  short  head  of  the 
biceps  externus. 


4  C.  internum  ;  internal  head;  anc.  in- 
ternus ;  v.  int. ;  brachialis  externus. 

5  C.  longum  ;  c.  medius  ;  middle  head; 
first  head ;  long  head  of  the  biceps  ex- 
ternus; anconseus  longus,  or  major. 

6  M.  anconaeus ;  m.  a.  quartus,  or  mi- 
nor ;  m.  brevis  cubiti ;  m.  cubitalis  Rio- 
lani. 


230  THE   MUSCULAR   SYSTEM. 

from  the  external  condyle  of  the  humerus,  and  is  inserted  into  the  trian- 
gular space  at  the  upper  and  outer  part  of  the  ulna. 

It  acts  with  the  triceps,  and  was  formerly  described  as  a  fourth  head 
to  this  muscle. 

MUSCLES  OF  THE  FRONT  OF  THE  FOREARM. 

The  Long  Pal/mar  muscle1  lies  between  the  radio-  and  ulno-carpal 
flexors.  It  arises  from  the  internal  condyle  and  intermuscular  partitions, 
and  forms  a  small  belly  terminating  in  a  long  tendon,  which  descends  to 
be  inserted  into  the  annular  ligament  of  the  wrist  and  the  palmar  fascia. 

The  Te'rete  Pro'nator2  is  a  small  muscle  extended  obliquely  across 
the  upper  part  of  the  front  of  the  forearm.  It  arises  from  the  internal 
condyle  of  the  humerus,  and  passes  outward  and  downward  to  be 
inserted  into  a  rough  surface  on  the  outer  side  of  the  radius. 

The  Quad'rate  Pro'nator3  is  a  square  muscle  crossing  the  lower  part 
of  the  forearm,  beneath  the  flexor  muscles.  It  arises  from  the  front  of 
the  lower  part  of  the  ulna,  and  passes  over  the  interosseous  membrane 
to  be  inserted  into  the  front  of  the  radius.  Superficially  it  is  invested 
with  a  thin  aponeurosis. 

The  two  pronator  muscles,  by  rotating  the  radius  inwardly  upon  the 
ulna,  pronate  the  hand ;  or,  in  other  words,  turn  it  with  the  palm  down- 
ward. 

The  Radio-carpal  Flexor4  lies  in  front  of  the  forearm,  extending 
obliquely  from  the  inner  condyle  to  the  outer  side  of  the  metacarpus. 
It  arises  from  the  internal  condyle  and  intermuscular  partitions,  and  con- 
verges to  a  long,  flat  tendon,  which,  after  passing  through  a  fibrous  canal 
at  the  outer  part  of  the  carpus,  is  inserted  into  the  base  of  the  second 
metacarpal  bone. 

The  Ulno-carpal  Flexor5  lies  superficially  on  the  ulnar  side  of  the 
forearm.  It  arises  from  the  internal  condyle  and  the  olecranon  and  by 
a  strong  aponeurosis  from  the  upper  part  of  the  inner  border  of  the 
ulna.  Its  belly  terminates  in  a  tendon,  which  is  inserted  into  the  pisiform 
bone  and  base  of  the  last  metacarpal  bone. 

1  M.  palmaris  longus ;  m.  ulnaris  gra-  pronator  transversus ;  m.  quadratus  ra- 
cilis ;  latescentis  chordae  ;  m.  epitrochlo-  dii ;  m.  cubito-radialis. 
carpi-palmaris.  *  M.  flexor  carpi-radialis;  m.  radialis 

2  M.  pronator  radii  teres;  m.  pronator  internus  ;  m.  palmaris  magnus. 
rotundus  ;  m.  p.  obliquus;  m.  epitrochlo-  5  M.  flexor  carpi-ulnaris ;   m.  ulnaris 
radialis.  internus  ;  m.  cubitalis  internus,  or  ante- 

3  M.   pronator   radii   quadratus ;    m.       rior. 


THE   MUSCULAR   SYSTEM. 


231 


Between  the  origin  of  this  muscle  from  the  humerus  and  the  ulna,  the 
ulnar  nerve  takes  its  course. 


FIG.  165. 


SUPERFICIAL  MUSCLES  OF  THE  FRONT  OF  THE  FORE- 
ARM. 1,  lower  part  of  the  biceps  flexor ;  2,  brachial 
muscle ;  3,  lower  part  of  the  triceps  extensor ;  4, 
terete  pronator;  5,  radio-carpal  flexor;  6,  long 
palmar  muscle ;  7,  superficial  flexor  of  the  fingers; 
8,  ulno-carpal  flexor;  9,  palmar  fascia;  10,  short 
palmar  muscle ;  11,  abductor  of  the  thumb ;  12, 
short  flexor  of  the  thumb  ;  13,  long  supinator ;  14, 
extensors  of  the  thumb.  The  crossing  and  trans- 
verso  bands  on  the  fingers  are  the  vaginal  liga- 
ments inclosing  the  flexor  tendons. 


FIG.  166. 


DEEP  MUSCLES  OP  THE  FRONT  OF  THE  FOREARM.  1, 
internal  lateral  ligament  of  the  elbow  joint ;  2. 
capsular  ligament  of  the  same;  3,  annular  liga- 
ment inclosing  the  head  of  the  radius;  4,  deep 
flexor  of  the  fingers ;  5,  long  flexor  of  the  thumb ; 
6,  quadrate  pronator;  7,  adductor  of  the  thumb;  8, 
9,  interosseous  muscles. 


The  Superficial  Flexor  of  the 
Fingers1  is  situated  in  front  of  the 
forearm,  between  the  preceding  muscles.  It  arises  from  the  internal  con- 
dyle,  the  internal  lateral  ligament,  the  coronoid  process  of  the  ulna,  and 
the  radius  below  its  tuberosity.  The  fleshy  belly  at  the  lower  third  of 
the  forearm  divides  into  four  tendons,  which  proceed  together  beneath  the 
annular  ligament  of  the  wrist,  and  diverge  to  be  inserted  into  the  base 


1  M.  flexor  sublimus  perforatus;  m.  f.  digitorum  sublimus,  or  perforatus. 


232 


THE   MUSCULAR   SYSTEM. 


of  the  second  phalanges  of  the  fingers.     In  front  of  the  first  phalanges 
the  tendons  are  split,  to  give  passage  to  the  tendons  of  the  deep  flexor. 
Between  the  ulnar  and  radial  origin  of  this  muscle  the  median  nerve 
pursues  its  course. 

FIG.  167. 


METACARPAL  AND  PHALANGIAL  BONES  OF  THE  FINGERS,  WITH  THEIR  TENDONS  AND  LIGAMENTS.  In  the 
upper  figure  the  flexor  tendons  are  retained  in  position  by  the  vaginal  ligaments  composed  of  transverse 
and  obliquely  crossing  bands ;  in  the  lower  figure  the  flexor  tendons  are  freed  from  the  vaginal  ligaments. 
1,  metacarpal  bone ;  2,  tendon  of  the  superficial  flexor ;  3,  tendon  of  the  deep  flexor,  passing  through  a 
perforation  (*)  of  the  former ;  4,  tendon  of  the  common  extensor ;  5,  a  lumbrical  muscle,  arising  from  tlie 
deep  flexor  tendon  and  inserted  into  the  extensor  tendon;  6,  an  interosseous  muscle,  also  inserted  into  the 
latter  tendon. 

The  Deep  Flexor  of  the  Fingers1  is  stronger  than  the  preceding 
muscle,  and  is  beneath  it.  It  arises  from  the  upper  two-thirds  of  the  front 
surface  of  the  ulna  and  from  the  contiguous  portion  of  the  interosseous 
membrane,  and  likewise  divides  into  four  tendons.  These,  after  passing 
through  the  annular  ligament  of  the  wrist,  take  their  course  through  the 
perforations  of  the  tendons  of  the  superficial  flexor,  and  are  inserted 
into  the  base  of  the  last  phalanges. 

The  Lum/brical  muscles,2  as  implied  by  the  name,  are  worm-like, 
fleshy  fasciculi,  four  in  number,  situated  in  the  palm  of  the  hand.  They 
arise  from  the  radial  side  of  the  tendons  of  the  deep  flexor,  and  proceed 
to  be  inserted  into  the  corresponding  side  of  the  tendinous  expansions 
on  the  back  of  the  fingers. 

The  Long-  Flexor  of  the  Thumb,3  situated  at  the  outer  side  of  the 
deep  flexor  of  the  fingers,  arises  from  the  front  of  the  radius  and  the 
contiguous  portion  of  the  interosseous  membrane.  The  fleshy  belly 
terminates  in  a  tendon,  which  passes  beneath  the  annular  ligament  of  the 


1  M.  flexor  profundus  perforans  ;  m.  f. 
digitorum  profundus,  or  perforans;  m.  f. 
tertii  internodii  digitorum;  m.  perforans 
manus. 


2  M.  lumbricales  ;  m.  fidicinales. 

3  M.  flexor  longus  pollicis  ;  m.  f.  tertii 
internodii,  or  longissimus  pollicis. 


THE   MUSCULAK   SYSTEM.  933 

wrist,  turns  outwardly,  and  proceeds  between  the  two  portions  of  the 
short  flexor  to  be  inserted  into  the  base  of  the  last  phalanx  of  the 
thumb. 

The  tendons  of  the  flexor  muscles  proceeding  to  the  fingers  are 
retained  in  their  position  by  the  vaginal  ligaments.1  In  their  passage 
beneath  the  latter  they  are  attached  to  the  front  of  the  phalanges  by 
narrow,  accessory  bands,2  apparently  serving  to  conduct  nutritious  vessels 
to  the  tendons.  Synovial  bursa?3  lining  the  vaginal  ligaments  and  fronts 
of  the  phalanges  are  thence  reflected  upon  the  flexor  tendons  and  their 
accessory  bands. 

MUSCLES  OF  THE  BACK  OF  THE  FOREARM. 

The  Common  Extensor  of  the  Fingers*  arises  from  the  external  con- 
dyle,  contiguous  intermuscular  partitions,  and  the  fascia  of  the  forearm. 
Below  the  middle  of  the  latter  its  fleshy  belly  separates  into  four  ten- 
dons, which  pass  beneath  the  posterior  annular  ligament,  and  diverge  to 
the  fingers,  upon  the  backs  of  which  they  expand.  As  they  pass  over 
the  first  phalanges  they  receive  an  addition  of  fibres  at  the  sides  from 
the  lumbrical  and  interosseous  muscles,  and  their  middle  portion  is  in- 
serted into  the  base  of  the  second  phalanges,  while  the  lateral  portions 
proceed  onward  and  converge  to  be  inserted  together  into  the  base  of 
the  last  phalanges.  On  the  back  of  the  hand  the  inner  three  of  the  ten- 
dons are  connected  together  by  short,  intervening  bands,  which  associate 
their  action  much  more  than  with  the  remaining  tendon. 

The  Long  Supina'tor5  lies  on  the  radial  side  of  the  forearm,  and  ex- 
tends from  near  the  middle  of  the  humerus  to  the  wrist.  It  arises  from 
the  external  condyloid  ridge  below  the  insertion  of  the  deltoid  muscle, 
and  converges  to  a  long,  flat  tendon,  which  is  inserted  into  the  base  of  the 
styloid  process  of  the  radius. 

The  Longer  Radio-carpal  Extensor6  is  partially  covered  by  the  pre- 
ceding muscle,  and  arises  just  below  it  from  the  same  ridge.  Its  belly 
converges  to  a  long,  flat  tendon,  which  descends  along  the  radius,  and  is 
inserted  into  the  base  of  the  second  metacarpal  bone. 

The  Shorter  Kadio-carpal  Extensor,7  partially  concealed  by  the  last 

1  Ligamenta  vaginalia.  5  M.  supinator  longus;  m.  s.  radii  lon- 

2  Vincula  vasculosa ;  v.  accessoria  ten-      gus  ;  m.  s.  major;  m.  brachio-radialis. 
dinum;  tenacula.  6  M.  extensor  carpi-radialis  longior; 

3  Vaginae  synoviales.  m.  radialis  externus  longior,  or  primus. 
*  M.  extensor  digitorum   communis ;          7  M.  extensor  carpi-radialis  brevior ; 

*m.  digitorum  tensor.  m.  radialis  externus  brevior,  or  secundus. 


234 


THE   MUSCULAR  SYSTEM. 


muscle,  arises  from  the  external  condyle  of  the  humerus,  and  is  inserted 
by  a  flat  tendon  into  the  base  of  the  third  metacarpal  bone. 


FIG.  168. 


MUSCLES  OF  THE  BACK  OF  THE  FOREARM.  1,  biceps 
flexor ;  2,  brachial  muscle ;  3,  triceps  extensor ;  4, 
long  supinator;  5,  longer  radio-carpal  extensor;  6, 
shorter  radio-carpal  extensor;  7,  insertion  of  the 
tendons  of  the  last  two  muscles;  8,  common  exten- 
sor of  the  fingers;  9,  extensor  of  the  little  finger; 
10,  ulno-carpal  extensor;  11,  short  supinator;  12, 
ulno-carpal  flexor ;  13,  metacarpal  and  first  phal- 
angial  extensors  of  the  thumb ;  14,  second  phalan- 
gial  extensor  of  the  thumb ;  15,  posterior  annular 
ligament. 


FIG.  169. 


DEEP  MUSCLES  ON  THE  BACK  OF  THE  FOREARM. 
1,  humerus ;  2,  olecranon ;  3,  ulna ;  4,  anconeus 
muscle ;  5,  short  supinator ;  6,  metacarpal  extensor 
of  the  thumb ;  7,  first  phalangial  extensor ;  8,  second 
phalangial  extensor  of  the  thumb;  9,  extensor  of 
the  index  finger ;  10,  the  dorsal  interosseous  muscle* 
between  the  metacarpal  bones. 


The  Ulno-carpal  Extensor1  lies 
at  the  ulnar  side  of  the  forearm, 
and  arises  from  the  external  con- 
dyle, the  upper  part  of  the  inner  border  of  the  ulna,  and  the  fascia  of  the 
forearm.     Its  belly  converges  to  a  long,  flat  tendon,  which  descends  to 
be  inserted  into  the  base  of  the  last  metacarpal  bone. 


1  M.  extensor  carpi-ulnaris ;  m.  ulnaris  externus;  m.  cubitalis  externus,  or  pos- 
terior. 


THE   MUSCULAR   SYSTEM.  235 

The  Extensor  of  the  Little  Finger1  lies  at  the  ulnar  side  of  the  com- 
mon extensor,  with  which  it  has  its  origin  ;  and  its  tendon,  after  passing 
through  a  separate  canal  of  the  annular  ligament,  conjoins  the  fourth 
tendon  of  the  common  extensor. 

The  Short  Supina'tor2  is  concealed  by  the  long  supinator  and  the 
radial  extensors.  It  arises  from  the  external  condyle  of  the  humerus, 
the  external  lateral  ligament  of  the  elbow  joint,  and  the  ulna,  and  winds 
obliquely  outward  and  downward  upon  the  radius,  into  the  upper  third 
of  which  it  is  inserted. 

The  Metacarpal  Extensor  of  the  Thumb3  crosses  the  forearm  obliquely 
below  the  preceding  muscle,  and  arises  from  the  ulna,  the  interosseous 
membrane,  and  the  radius.  Its  belly  terminates  in  a  tendon,  which 
crosses  those  of  the  radio-carpal  extensors,  and,  after  passing  through  a 
groove  in  front  of  the  styloid  process  of  the  radius,  is  inserted  into  the 
base  of  the  metacarpal  bone  of  the  thumb. 

The  First  Phalan'gial  Extensor  of  the  Thumb4  is  a  small  muscle  situ- 
ated below  the  preceding  to  its  ulnar  side,  and  has  the  same  points  of 
origin.  Its  fleshy  belly  terminates  in  a  narrow  tendon,  which  accompa- 
nies that  of  the  preceding  muscle,  and  is  inserted  into  the  base  of  the 
first  phalanx  of  the  thumb. 

The  Second  Phalan'gial  Extensor  of  the  Thumb5  arises  below  the 
preceding  muscle  from  the  ulna  and  interosseous  membrane.  Its  belly 
terminates  in  a  tendon,  which  passes  through  a  distinct  canal  of  the  an- 
nular ligament  from  that  occupied  by  the  tendons  of  the  first  phalangial 
and  metacarpal  extensors,  and  proceeds  to  be  inserted  into  the  base  of 
the  last  phalanx  of  the  thumb. 

The  Extensor  of  the  Index  Finger6  lies  at  the  ulnar  side  of  the  pre- 
ceding muscle,  and  has  the  same  points  of  origin.  Its  tendon  of  inser- 
tion passes  through  a  groove  of  the  radius,  and  conjoins  the  tendon  of 
the  common  extensor  to  the  index  finger. 

1  M.  extensor  minimi  digiti,  or  m.  e.       pollicis  primus;  m.  e.  secundi  internodii 
proprius  m.  d. ;  m.  auricularis.  ossis  pollicis. 

2  M.  supinator  radii  brevis,  or  minor  ;  &  M.  extensor  secundi  internodii  polli- 
m.  epicondylo-radialis.  cis ;  m.  extensor  longus,  or  major  polli- 

3  M.  extensor  ossis  metacarpi  pollicis  ;  cis ;  m.  e.  pollicis  secundus;    m.  e.  tertii 
m.  abductor  longus  pollicis ;  m.  e.  primi  internodii  ossis  pollicis. 

internodii  ossis  pollicis.  6  M.  extensor  indicis ;    indicator;  m. 

*  M.  extensor  primi  internodii  pollicis;  ext.  proprius  indicis  ;  m.  e.  p.  primi  di- 
m.  extensor  brevis,  or  minor  pollicis ;  m.  e.  giti. 


236 


THE   MUSCULAR   SYSTEM. 


MUSCLES  OF  THE  HAND. 


FIG.  170. 


The  Short  Pal'mar  muscle1  is  a 
thin  layer  of  fleshy  fibres  situated 
beneath  the  skin  at  the  inner  side 
of  the  palm  of  the  hand.  It  arises 
from  the  annular  ligament  and  pal- 
mar fascia,  and  proceeds  inwardly 
to  be  attached  to  the  integument. 

MUSCLES  OF  THE  PALMAR  SURFACE  OF  THE  HAND. 
1,  anterior  annular  ligament ;  2,  origin  and  inser- 
tion of  the  abductor  of  the  thumb ;  its  belly  re- 
moved so  as  to  expose  3,  the  metacarpal  flexor ;  4, 5, 
two  bellies  of  the  short  flexor;  6,  adductor  of  the 
thumb;  7,  lumbrical  muscles;  8,  tendons  of  the 
deep  flexor  of  the  fingers  passing  through  the  slits 
of  the  superficial  tendons;  9,  tendon  of  the  long 
flexor  of  the  thumb,  passing  from  between  the 
bellies  of  the  short  flexor;  10,  abductor  of  the  little 
finger;  11,  short  flexor  of  the  little  finger,  with  the 
edge  of  the  adductor  seen  beneath;  12,  pisiform 
bone ;  13,  first  interosseous  muscle. 


MUSCLES  OF  THE  BALL  OF  THE  THUMB. 

The  Abductor2  is  the  most  superficial  and  external  of  the  muscles  of 
the  ball  of  the  thumb.  It  arises  from  the  annular  ligament  of  the  wrist, 
and  is  inserted  into  the  base  of  the  first  phalanx  of  the  thumb. 

The  Metacarpal  Flexor,3  beneath  the  preceding,  arises  from  the  same 
source,  and  is  inserted  into  the  length  of  the  metacarpal  bone  of  the 
thumb. 

The  Short  Flexor4  consists  of  two  portions,  between  which  lies  the 
tendon  of  the  long  flexor  of  the  thumb.  It  arises  from  the  annular  liga- 
ment and  the  second  row  of  c  >al  bones,  and  is  inserted  tendinously 
into  the  base  of  the  first  phala  of  the  thumb.  Within  its  tendinous 
insertion  the  sesamoid  bones  are  imbedded 

The  Adductor5  is  a  triangular  muscle,  arising  from  the  length  of  the 
1  M.  palmaris  brevis;  caro  quadrate;       opponens  pollicis;  m.  f.  primi  internodii 


m.  carpaeus. 

2  M. abductor  pollicis;  m.  a.  brevis  pol- 


pollicis ;  m.  antithenar. 

*  M.  flexor  brevis  pollicis ;  m.  f.  secundi 


licis;  m.  a.  brevis  alter  p. ;   m.  scapho-      internodii  p.;  m.  f.  primi  et  secundi  i.  p.; 


carpo-superphalangeus  pollicis. 

3  M.  flexor  ossis  metacarpi  pollicis ;  m. 


m.  thenar. 

5  M.  adductor  pollicis ;  m.  metacarpo- 
phalangeus  pollicis. 


THE  MUSCULAR  SYSTEM.  237 

middle  metacarpal  bone,  and  converging  to  be  inserted  into  the  base  of 
the  first  phalanx  of  the  thumb. 

MUSCLES  OF  THE  LITTLE  FINGER. 

The  Abductor1  lies  on  the  margin  of  the  palm.  It  arises  from  the 
pisiform  bone,  and  is  inserted  into  the  base  of  the  first  phalanx  and  ex- 
tensor tendon  of  the  little  finger. 

The  Short  Flexor2  arises  from  the  annular  ligament  of  the  wrist  and 
the  unciforrn  bone,  and  is  inserted  into  the  base  of  the  first  phalanx  of 
the  little  finger.  It  is  not  unfrequently  inseparable  from  the  preceding 
muscle. 

The  Adductor3  arises  from  the  same  points  as  the  preceding  muscle, 
and  is  inserted  into  the  length  of  the  metacarpal  bone  of  the  little  finger. 

THE  INTEROSSEOUS  MUSCLES. 

The  Interos'seous  muscles4  are  seven  in  number,  and,  as  implied  by 
their  name,  are  situated  in  the  intervals  of  the  metacarpal  bones — four 
on  the  back,  and  three  on  the  palm  of  the  hand. 

The  Dorsal  Interos'seous  muscles,5  four  in  number,  arise  from  the 
contiguous  sides  of  the  metacarpal  bones,  and  each  forms  a  penniform 
belly,  terminating  in  a  tendon,  which  partially  conjoins  the  extensor  ten- 
dons on  the  back  of  the  finger,  and  is  partially  inserted  into  the  base  of 
the  first  phalanx. 

The  first  of  this  series  is  inserted  into  the  radial  side  of  the  index 
finger,  and  is  an  abductor;  the  succeeding  two  are  inserted  into  the 
opposed  sides  of  the  middle  finger,  and  act  as  an  abductor  and  adductor ; 
and  the  last  one  is  inserted  into  the  ulnar  side  of  the  ring  finger,  and  is 
an  adductor. 

The  Palmar  Interos'seous  muscles,"  three  in  number,  arise  from  a 
single  side  of  the  metacarpal  bones  of  t$e  index,  ring,  and  little  fingers, 
and  terminate  in  the  same  manner  as  1'.:$'  dorsal  series.  The  first  is  on 
the  ulnar  side,  and  is  an  adductor,  and  the  other  two  are  on  the  radial 
side,  and  are  abductors. 

1  M.  abductor  minimi  digiti ;  m.  exten-          3  M.  adductor  minimi   digiti ;    m.   a. 
sor  tertii  internodii  m.  d.;  m.  carpo-pha-       metacarpi    m.    d.;     m.    carpo-metacar- 
langeus   m.    d.;    m.   hypothenar   minor      peus  m.  d. 

metacarpeus.  *  M.  interossei. 

2  M.  flexor  brevis,  or  parvus  minimi          5  M.  i.  externi ;  m.  i.  bicipites. 
digiti.  6  M.  i.  interni. 


238  THE   MUSCULAR   SYSTEM. 


THE  LOWER  EXTREMITIES. 

The  Lower  Extremities,  which  support  and  carry  the  other  portions 
of  the  body,  are  accordingly  larger  and  stronger,  and  provided  with 
more  powerful  muscles  than  the  upper  extremities.  At  the  back  part  of 
the  hips  are  the  buttocks  or  nates,1  separated  by  the  fissure  of  the  anus, 
and  from  the  thighs  below  by  the  sub-ischiatic  grooves.  The  thigh.2  is 
separated  from  the  abdomen  by  the  groin  or  inguinal  region,  and  gradu- 
ally becomes  narrowed  to  the  knee.3  Behind  the  latter  is  the  space 
called  the  poplite'al  region,  or  hollow  of  the  knee,4  bounded  on  each 
side  by  the  "ham-strings."  The  condyles  of  the  femur  and  tibia  pro- 
duce the  lateral  prominences  of  the  knee,  the  knee-cap  producing  the 
eminence  in  front.  The  calf5  or  thick  mass  of  the  leg6  narrows  down- 
ward to  the  "tendon  of  Achilles,"  which  terminates  at  the  heel.7  The 
ankles  correspond  with  the  malleoli  of  the  tibia  and  fibula. 

The  skin  of  the  buttock  is  thick,  but  becomes  thin  in  the  fissure  of  the 
anus.  Upon  the  outer  part  of  the  thigh  and  leg  it  is  thick,  dense,  and 
comparatively  dull  in  sensibility ;  becomes  thinner,  more  extensible,  and 
sensitive  toward  the  inner  part,  and  is  everywhere  quite  movable.  Upon 
the  back  of  the  foot  the  skin  is  thin  and  extensible ;  but  upon  the  sole, 
is  thick,  inextensible,  and  quite  immovable. 

FASCIA  OF  THE  LOWER  EXTREMITY. 

The  Superficial  fascia  of  the  lower  extremity,  as  in  other  divisions  of 
the  body,  is  in  most  parts  separable  into  two  layers,  of  which  the  inner 
one  is  thin  and  membranous,  the  outer  one  loose  in  texture,  and  more  or 
less  filled  with  fat. 

Upon  the  buttock  the  superficial  fascia  is  ordinarily  occupied  with  a 
large  quantity  of  fat.  Upon  the  thigh  and  leg  it  also  usually  contains 
much  fat,  except  over  the  great  trochanter  and  the  patella,  in  which 
positions  synovial  bursas  are  substituted.  In  the  sole  of  the  foot  it  is 
always  occupied  with  fat,  and  is  most  intimately  blended  with  the  struc- 
ture of  the  skin.  At  the  heel,  and  bend  of  the  first  and  last  metatarsal 
bones,  it  contains  synovial  bursa?.  Between  the  fatty  and  membranous 
layers  of  the  superficial  fascia,  the  superficial  veins  and  cutaneous  nerves 
have  their  course. 

1  Glutia;  sedilia;  clunes;  podex  ;  pos-          4  Popliteal  fossa;  the  hock;  the  hough; 
teriors  ;  bottom.  the  ham. 

2  Femur ;  crus ;  merus.  5  Sura ;  gastrocnemium. 
8  Genu.  6Crus;  scelos;  cneme. 

7  Calx ;  talus. 


THE  MUSCULAR  SYSTEM.  239 

The  fatty  layer  at  the  groin  and  hip  is  continuous  with  the  correspond- 
ing layer  of  the  superficial  fascia  of  the  abdomen.  The  deeper  or  mem- 
branous layer  adheres  to  Poupart's  ligament  and  the  crest  of  the  ilium. 
At  the  saphenous  opening  it  is  pierced  by  the  cutaneous  vessels  of  the 
contiguous  regions,  from  which  circumstance  this  perforated  portion  of 
the  superficial  fascia  is  called  the  criVriform  fascia.1 

The  Deep  fascia  of  the  lower  extremity,  like  that  of  the  upper  ex- 
tremity, forms  a  complete  envelope  to  the  limb,  sends  partitions  between 
the  muscles,  and  gives  sheaths  to  the  great  blood-vessels.  It  is  called, 
from  its  relative  positions,  the  femoral  fascia,  the  crural  fascia,  and  the 
fascia  of  the  foot. 

The  Fern/oral  fas'cia  or  fas'cia  la'ta,2  is  attached  along  the  crest 
of  the  ilium,  the  back  of  the  sacrum  and  coccyx,  the  border  of  the 
ischium  and  pubis  and  Poupart's  ligament,  with  which  it  is  continuous. 
Upon  the  great  gluteal  muscle  it  forms  a  thin  investment;  but  in  ad- 
vance of  this,  and  extending  in  the  same  line  the  entire  length  of  the 
outer  part  of  the  thigh,  it  is  so  thick  and  strong  as  to  appear  like  an 
aponeurosis.  This  portion  of  the  fascia  is  composed  of  longitudinal 
fibres  strengthened  by  transverse  ones ;  gives  partial  origin  to  the  middle 
gluteal  muscle ;  receives,  over  the  position  of  the  great  trochanter,  part 
of  the  insertion  of  the  great  gluteal  muscle;  and  after  insheathing  its 
own  peculiar  tensor  muscle,  receives  the  insertion  of  this  altogether.  In 
passing  from  the  outer  to  the  inner  part  of  the  thigh,  the  femoral  fascia 
becomes  gradually  thinner,  and  is  mainly  composed  of  transverse  fibres. 

Between  all  the  muscles  it  sends  partitions,  among  the  most  important 
of  which  are  the  so-called  external  and  internal  intennuscular  par- 
titions.3 The  former  of  these  is  a  strong  process  separating  the  quadriceps 
extensor  and  the  biceps  flexor,  and  attaching  itself  to  the  asperous  ridge 
from  the  insertion  of  the  great  gluteal  muscle  to  the  outer  condyle  of 
the  femur.  The  other  is  a  thinner  partition  separating  the  quadriceps 
extensor  from  the  adductor  muscles,  and  connecting  itself  with  the  aspe- 
rous ridge  leading  to  the  inner  condyle.  At  the  knee  the  fascia  receives 
offsets  from  the  extensor  and  flexor  tendons,  forms  a  general  envelope4 
to  the  joint,  and  becomes  continuous  with  the  crural  fascia. 

Below  the  groin,  the  femoral  fascia  is  so  important  in  its  relations  with 
the  femoral  blood-vessels  and  the  subject  of  femoral  hernia,  that  it  re- 
quires special  attention.  The  inner  and  outer  portions  of  the  fascia, 

1  Fascia  cribrosa.  3  Ligamentum    intermusculare   exter- 

2  Fascia  femoris ;  fHata  aponeurosis  ;       num  et  internum. 

f.  aponeurotica  femoris :  vagina  femoris;  *  Involucrum  generale. 

crural,  or  femoral  aponeurosis. 


240 


THE   MUSCULAR  SYSTEM. 


from  the  muscles  they  immediately  invest,  are  conveniently  named  the 
pectineal  and  sartorial  fascia. 

FIG.  171. 

VIEW  OF  THE  INGUINAL  CANAL.  1,  por- 
tion of  the  fleshy  belly  of  the  external  ob- 
lique muscle;  2,  its  aponeurosis;  3,  por- 
tion of  the  latter  raised  up,  exposing  the 
inguinal  canal;  4,  linea  alba;  5,  insertion 
of  the  aponeurosis  of  the  external  oblique 
into  the  body  of  the  pubis;  6,  its  insertion 
into  the  spine  of  the  pubis,  named  Pou- 
part's  ligament;  7,  division  of  the  fibres 
of  the  aponeurosis  crossed  by  transverse 
fibres ;  8,  external  abdominal  ring,  the  ter- 
mination of  the  inguinal  canal :  9,  anterior 
superior  spinous  process,  the  origin  of 
Poupart's  ligament ;  10,  arching  lower  bor- 
der of  the  internal  oblique  and  transverse 
muscles;  11,  conjoined  tendon  of  the  latter 
muscles ;  12,  fibres  of  the  cremaster  muscle 
descending  on  the  spermatic  cord  from  the 
edges  of  the  muscles  just  named ;  13,  rests 
on  the  transverse  fascia;  to  its  right  are 
the  epigastric  vessels  crossing  the  course 
of  the  inguinal  canal;  14,  iliac  portion  of 
the  femoral  fascia ;  15,  pubic  portion ;  16, 
falciform  process;  17,  saphenous  opening: 
IS,  saphenous  vein  joining  the  femoral  vein  through  the  saphenous  opening;  19,  the  femoral  artery  and 
vein  exposed  by  raising  the  portion  of  fascia  which  forms  the  falciform  process ;  20,  suspensory  ligament 
of  the  penis. 

The  pectine'al  fas'cia1  invests  the  corresponding  muscle  behind  the 
femoral  blood-vessels.  It  is  attached  along  the  body  and  pectineal  line 
of  the  pubis,  and  at  its  outer  border  becomes  continuous  with  the  iliac 
fascia  investing  the  psoas  and  iliac  muscles,  and  with  the  posterior  layer 
of  the  sartorial  fascia. 

The  sarto'rial  fas'cia,2  after  including  the  corresponding  muscle,  in 
the  groin  is  attached  along  Poupart's  ligament  and  extends  in  front  of 
the  femoral  blood-vessels.  A  couple  of  inches  below  the  pubis,  it  be- 
comes continuous  with  the  pectineal  fascia,  and  between  these  two  points 
includes  an  oval  space  named  the  saphe'nous  opening,3  from  the  long 
saphenous  vein  entering  at  this  position  to  join  the  femoral  vein.  The 
outer  part  of  the  saphenous  opening  is  defined  by  a  lunated  edge  of  the 
sartorial  fascia,  named  the  fal'ciform  process,4  the  upper  extremity5  of 


1  Pubic  portion  of  the  femoral  fascia, 
or  fascia  lata ;  fascia  ischio-pubica. 

2  Iliac  portion  of  the  femoral  fascia,  or 
fascia  lata ;  fascia  ilio-pectinea. 

3  Fossa  ovalis ;  inferior  orifice  of  the 
crural  canal. 


4  Plica  falciformis ;    falciform  expan- 
sion, or  semilunate  edge  of  the  fascia 
lata. 

5  Cornu  superius ;  upper  horn ;  Key's 
ligament ;  femoral  ligament. 


THE   MUSCULAR   SYSTEM.  241 

which  is  continuous  with  Gimbernat's  ligament;  the  lower  extremity,1 
with  the  pectineal  fascia.  The  inner  part  and  bottom  of  the  opening  are 
formed  by  the  latter  fascia  as  it  dips  from  within,  outwardly,  behind  the 
femoral  blood-vessels. 

The  saphenous  opening  is  occupied  with  a  portion  of  the  superficial 
fascia,  called  cribriform  fascia,2  from  its  being  perforated  by  many 
small  superficial  vessels  passing  between  the  contiguous  parts  and  the 
femoral  vessels.  The  cribriform  fascia  is  continuous  with  the  falciform 
process,  and  careful  manipulation  is  required  to  distinguish  the  lunated 
edge  of  the  latter.  When  the  fascia  is  removed,  the  falciform  process  is 
observed  to  overlie  the  femoral  vessels ;  its  upper  and  lower  extremities 
are  usually  well  marked,  while  the  middle  portion  is  less  defined. 

The  Cru/ral  fascia3  or  deep  fascia  of  the  leg,  for  the  most  part  well 
marked  and  strong,  adheres  to  the  heads  of  the  tibia  and  fibula,  to  the 
anterior  and  internal  borders  of  the  former  bone,  and  to  both  malleoli. 
It  receives  offsets  from  the  tendons  of  insertions  of  the  sartorius,  gra- 
cilis,  semitendinous,  and  biceps  muscles,  and  is  mainly  composed  of 
transverse  fibres.  It  is  strongest  in  the  outer  part  of  the  leg,  where  it 
gives  partial  origin  to  the  heads  of  the  muscles,  and  is  continuous  with 
their  internmscular  partitions.  It  is  thinnest  on  the  back  of  the  leg,4 
where  it  consists  of  a  layer  investing  the  muscles  of  the  calf,  and  another5 
separating  the  latter  from  the  deeper  muscles. 

In  the  vicinity  of  the  ankle  joint,  the  crural  fascia  receives  an  acces- 
sion of  fibres,  much  increasing  its  strength,  and  constituting  the  annular 
ligaments,  which  bind  down  the  tendons  of  the  muscles  as  they  turn  for- 
ward from  the  leg  to  the  foot. 

The  anterior  an'nular  ligament6  is  a  strong  band  extending  obliquely 
in  front  of  the  ankle  joint,  from  the  inner  malleolus  to  the  anterior  and 
outer  part  of  the  calcaneum.  It  consists  of  two  layers,  which  inclose 
the  tendons  in  several  compartments  as  they  cross  the  ankle  joint.  Thus 
the  tendons  of  the  long  extensor  of  the  toes  occupy  a  compartment  next 
to  the  fibula,  that  of  the  anterior  tibial  muscle  occupies  another  next  to 
the  tibia,  and  the  tendon  of  the  extensor  of  the  great  toe  an  intermediate 
compartment.  The  anterior  tibial  blood-vessels  and  nerve  are  behind 
the  ligament.  A  band  of  fibres,7  above  the  ankle  joint,  extended  be- 
tween the  front  of  the  tibia  and  the  fibula,  is  sometimes  described  as 
a  portion  of  the  anterior  annular  ligament ;  and  another  band  crosses 

1  Cornu  inferius;  lower  horn.  5  Deep  fascia  of  the  leg;  deep  crural 

2  F.  cribriformis.          %  fascia. 

3  Fascia  cruralis.  s  Lig.  annulare  anterius;  annular  liga- 
*  In  this  position  called  sural  fascia ;       ment  of  the  tarsus. 

f.  suralis.  ?  Lig.  transversum. 

16 


242  THE    MUSCULAR   SYSTEM. 

the  annular-  ligament  from  the  external  malleolus  to  the  inner  side  of 
the  tarsus.1 

The  internal  an'nular  ligament2  is  a  band  of  loose  fibres  extending 
from  the  internal  malleolus  to  the  back  of  the  astragalus  and  the  inner 
side  of  the  calcaneum.  It  converts  the  groove  at  the  back  of  the  inter- 
nal malleolus  into  a  canal  for  the  passage  of  the  tendons  of  the  posterior 
tibial  and  long  flexor  muscles ;  and  the  grooves  at  the  back  of  the  astra- 
galus and  beneath  the  calcaneum  into  a  canal  for  the  passage  of  the 
tendon  of  the  long  flexor  of  the  great  toe.  Between  these  two  canals 
the  ligament  transmits  the  posterior  tibial  vessels  and  nerves.  A  thin 
offset  from  the  ligament  extends  superficially  to  the  tendon  of  Achilles 
and  the  tuberosity  of  the  calcaneum. 

The  external  an'nular  ligament3  is  less  marked  than  the  preceding, 
and  consists  of  a  band  of  loose  fibres  starting  from  the  external  malleo- 
lus to  be  attached  to  the  outer  part  of  the  calcaneum,  and  binding  down 
the  tendons  of  the  peroneal  muscles. 

As  the  tendons  of  the  muscles  pass  in  their  course  from  the  leg  to 
the  foot,  beneath  the  annular  ligaments,  they  are  invested  with  synovial 
bursse. 

The  fascia  on  the  back  of  the  foot  is  a  thin  extension  from  the  ante- 
rior annular  ligament.  The  plantar  fascia4  consists  of  three  portions, 
as  in  the  case  of  the  palmar  fascia.  The  inner  and  outer  portion  is  thin, 
and  invests  the  small  muscles  of  the  toes.  The  middle  portion  is  strongest, 
and  resembles  the  corresponding  portion  of  the  palmar  fascia.  It  is 
composed  of  longitudinal,  diverging  fibres,  strengthened  with  transverse 
ones,  and  forms  a  triangular  investment  to  the  short  flexor  of  the  toes, 
to  which  it  gives  partial  origin.  Its  apex  is  attached  to  the  tuberosity 
of  the  calcaneum,  and  its  base  divides  into  five  processes,  each  of  which 
subdivides  to  be  inserted  into  the  metaoarpo-phalangial  and  contiguous 
vaginal  ligaments.  At  the  sides  it  is  continuous  with  the  lateral  portions 
of  the  fascia,  and  with  intermuscular  partitions  dipping  into  the  sole. 

The  vag'inal  ligaments  which  inclose  the  flexor  tendons  of  the  toes 
have  the  same  arrangement  as  those  of  the  fingers. 

SKETCH  OF  THE  ANATOMY  CONCERNED  IN  FEMORAL  HERNIA. 

The  position  of  the  groin  is  defined  by  Poupart's  ligament,5  which  is 
the  line  of  continuity  of  the  aponeurosis  of  the  external  oblique  muscle 

1  Forming  with  the  annular  ligament,       turn  externum  ^  retinaculuin  tendinum 
the  lig.  cruciatum.  pereneorum. 

2  Lig.  annulare  internum ;   1.  lacinia-  *  Aponeurosis  plantaris. 

turn  internum.  5  Lig.    Pouparti ;    1.   Fallopii ;    crural 

3  Lig.  annulare  externum  ;   1.  lacinia-       arch. 


THE   MUSCULAR  SYSTEM.  243 

of  the  abdomen  with  the  femoral  fascia,  extending  from  the  anterior 
superior  spinous  process  of  the  ilium  to  the  spine  of  the  pubis. 

Poupart's  ligament  constitutes  the  femoral  arch.,1  the  bottom  of  which 
is  formed  by  the  anterior  border  of  the  ilium  and  the  horizontal  ramus  of 
the  pubis.  The  inner  part  of  the  arch  is  formed  by  Gimbernat's  liga- 
ment,2 which  is  a  triangular  process  from  Poupart's  ligament,  extending 
a  short  distance  outwardly  along  the  pectineal  line  of  the  pubis. 

The  femoral  arch  is  occupied  externally  by  the  iliac  and  psoas  muscles, 
with  the  anterior  crural  nerve  situated  in  the  angular  interval  of  their 
conjunction.  Internally  it  is  occupied  by  the  femoral  artery,  vein,  and 
lymphatics,  inclosed  together  within  a  sheath,  and  resting  on  the  pec- 
tine'al  fascia,3  which  invests  the  corresponding  muscle. 

Below  the  inner  part  of  Poupart's  ligament  is  the  oval  space,  named 
the  saphe'nous  opening,  from  its  admitting  the  saphenous  vein  to  join 
the  femoral  vein.  The  opening  is  defined  externally  by  the  lunated 
edge  of  the  fal'ciform  process4  of  the  sarto'rial  fascia.5  The  upper  end6 
of  this  process  is  continuous  with  both  Gimbernat's  and  Poupart's  liga- 
ment, and  its  lower  end  is  continuous  with  the  pectineal  fascia.  The 
saphenous  opening  is  occupied  by  the  cribriform  fascia,7  a  portion 
of  the  superficial  fascia,  so  named  from  its  perforated  condition,  aris- 
ing from  the  transmission  of  the  superficial  vessels  of  the  neighboring 
parts. 

Behind  the  falciform  process,  from  without  inwardly,  lie  in  succession 
the  femoral  artery,  vein,  and  lymphatics,  which  together  are  inclosed  in 
a  sheath8  closely  connected  with  the  contiguous  fasciae.  The  femoral 
vessels  included  within  their  sheath  may  be  viewed  as  occupying  the  tube 
of  a  membranous  funnel  whose  expanded  portion  is  formed  by  the  trans- 
verse, iliac,  and  pelvic  fascia  of  the  abdomen  and  pelvis.  Between  the 
femoral  vein  and  Gimbernat's  ligament,  within  the  sheath  of  the  femoral 
vessels,  is  a  small  space  named  the  fem'oral  ring.9  This  is  occupied 
with  lymphatic  vessels,  and  a  gland  enveloped  in  some  loose  connective 
tissue,10  and  is  the  position  at  which  femoral  hernia  occurs. 

When  the  femoral  ring  is  cleared  of  its  contents,  the  end  of  the  little 
finger  may  be  introduced  into  it  from  the  abdomen  to  the  upper  part  of 


1  Crural  arch.  6  Key's  ligament. 

2  Lig.  Gimbernati ;  Key's  ligament.  7  F.  cribrosa. 

3  Pubic  portion  of  the  fascia  lata.  8  Femoral    sheath ;     vagina    vasorum 
*  Plica  falciformis ;    lunated  edge  of  cruralium. 

the  fascia  lata.  9  Crural  ring ;  annulus  cruralis. 

5  Iliac  portion  of  the  fascia  lata.  10  Septum  crurale ;    septum   transver- 

sum ;  crural  septum. 


244  THE   MUSCULAR   SYSTEM. 

the  saphenous  opening,  a  depth  of  about  half  an  inch.1  Its  internal 
and  anterior  boundary2  is  the  edge  of  Gimbernat's  ligament  continuous 
with  the  edge  of  the  falciform  process ;  its  outer  boundary  the  femoral 
vein,  and  its  posterior  boundary  the  pubis  and  pectineal  fascia. 

When  the  lower  limb  is  extended  and  rotated  with  the  toes  directed 
outwardly,  the  falciform  process  and  Gimbernat's  ligament  become  tense, 
and  the  femoral  ring  is  narrowed ;  and  when  the  limb  is  flexed  and  ro- 
tated with  the  toes  directed  inwardly,  the  same  points  become  relaxed, 
and  the  ring  is  widened.3  As  the  seat  of  constriction  or  strangulation 
of  femoral  hernia  occurs  within  the  circle  of  the  femoral  ring,  the  facts 
just  mentioned  afford  important  indications  as  to  the  mode  of  treatment. 

Besides  the  femoral  vein,  other  blood-vessels  in  relation  with  the  femo- 
ral ring  are  the  epigastric  artery  and  veins  situated  above  it  externally. 
When,  as  occasionally  happens,  the  obturator  artery  is  derived  from  the 
external  iliac,  as  this  is  about  to  emerge  from  the  femoral  arch,  it 
descends  at  the  outer  or  sometimes  at  the  inner  side  of  the  femoral  ring. 

In  femoral  hernia,  the  hernial  sac,  consisting  of  a  pouch  of  perito- 
neum containing  a  portion  of  the  bowels,  descends  through  the  femoral 
ring  within  the  sheath  of  the  femoral  blood-vessels.  Arriving  at  the 
saphenous  opening,  and  finding  least  resistance  in  front,  it  protrudes  for- 
ward, and  subsequently,  as  it  increases,  extends  outwardly  in  the  course 
of  the  groin.  Such  a  hernia  has  for  its  coverings  from  without  inwardly, 
the  skin,  the  subjacent  fatty  layer  of  the  superficial  fascia,  and  lastly,  a 
fibrous  layer,4  more  or  less  distinct,  and  derived  from  the  cribriform  fascia 
and  the  sheath  of  the  femoral  blood-vessels. 


MUSCLES  OF  THE  BUTTOCK. 

The  Great  Glu'teal  muscle5  is  a  thick,  lozenge-shaped  mass,  composed 
of  coarse  fleshy  fasciculi,  and  extending  from  the  back  of  the  pelvis  to 
the  upper  and  outer  part  of  the  thigh.  It  arises  from  the  posterior 
fourth  of  the  crest  of  the  ilium,  the  posterior  surface  of  the  sacrum  and 

1  The  depth  of  space  has  been  named  Gimbernat's  ligament,  a  semispiral  edge, 
the  femoral  canal,  its  upper  orifice  being  which  becomes  more  enrolled,  and  con- 
the  femoral  ring,  its   lower   orifice  the  sequently  includes    a    narrower    space, 
saphenous  opening.  when  the  limb  is  rotated  outwardly,  and 

2  Usually  stated  to  be  Poupart's  liga-  becomes    partially   unwound   when   the 
ment,  but  as  the  falciform  process  is  con-  limb  is  rotated  inwardly. 

tinuous  with  both  Gimbernat's  and  Pou-  4  Fascia  propria  of  femoral  hernia, 

part's  ligament,  the  anterior  boundary  5  M.  glutseus  magnus,  major,  maximus, 

may  be  considered  as  stated  in  the  text.  or  extimus ;  m.  sacro-fernoralis ;  m.  ilio- 

3  The    falciform   process   forms,  with  sacro-femoralis. 


THE   MUSCULAR  SYSTEM. 


245 


j  but  the  middle  and  small  gluteal  muscles  may  rotate  them  either  inwardly 
\^or  outwardly,  according  as  their  posterior  or  anterior  fibres  are  brought 
coccyx,  and  from  the  greater  sacro-ischiatic  ligament.  From  this  origin 
its  fleshy  fasciculi  proceed  outward  and  downward,  and  terminate  in  a 
thick  aponeurosis,  which  is  inserted  into  the  femoral  fascia  over  the 
greater  trochanter  of  the  femur,  and  into  the  rough  surface  extending 
from  the  latter  process  to  the  asperous  ridge. 

The  lower  border  of  this  muscle  forms  the  fold  of  the  buttock,  and  in 
the  erect  position  of  the  body  covers  the  tuberosity  of  the  ischium,  but 
glides  from  it  in  the  sitting  position.    Between  its  tendon  and  the  greater 
trochanter  of   the   femur   a  large 
synovial  bursa  is  interposed,  and 
another    is   situated   between   the 
muscle  and  the  tuberosity  of  the 
ischium. 

The  Middle  Glu'teal  muscle,1 
covered  at  its  fore  part  by  a  thick 
portion  of  the  femoral  fascia,  and 
at  its  back  part  by  the  preceding 
muscle,  arises  from  the  dorsal  sur- 
face of  the  ilium,  between  the  crest 
of  the  latter  and  the  superior  curved 
line,  and  from  the  investing  femoral 
fascia.  Descending,  its  fasciculi 
converge  to  a  short,  thick  tendon, 
which  is  inserted  into  the  outer  sur- 
face of  the  greater  trochanter.  Be- 
tween the  upper  part  of  the  latter 
and  the  tendon,  a  synovial  bursa  is 
interposed. 

The  Small  Glu'teal  muscle,2  con- 
cealed by  the  preceding,  arises  from 
the  dorsal  surface  of  the  ilium  be- 
tween the  superior  and  inferior 
curved  lines,  and  converges  to  a 

tendon,  which  is  inserted  into  the  inner  part  of  the  summit  of  the  greater 
trochanter.  Between  the  latter  and  the  tendon  a  synovial  bursa  is  inter- 
posed. 


MUSCLES  OF  THE  BUTTOCK.  1,  ilium;  2,  sacrum: 
3.  posterior  sacro-iliac  ligament;  4,  tuberosity  of  the 
ischium ;  5,  great  sacro-ischiatic  ligament;  6,  small 
sacro-ischiatic  ligament;  7,  greater  trochanter;  8, 
small  gluteal  muscle;  9,  pyriform  muscle;  10,12, 
geminous  muscle,  including  between  its  two  fasci- 
culi the  termination,  11,  of  the  internal  obturator 
muscle;  13,  quadrate  femoral  muscle;  14,  upper 
part  of  the  great  adductor  of  the  thigh;  15,  exter- 
nal vastus  muscle ;  16,  biceps  flexor ;  17,  gracilis ; 
18,  semi-tendinous  muscle. 


1  M.  glutams  medius,  or  secundus ;  m.  ilio-trochanterius. 

2  M.  glutaeus  minimus,  minor,  tcrtixis,  or  intimus;  m.  ilio-ischio-trochanterius. 


246  THE   MUSCULAR  SYSTEM. 

The  External  Obtu'rator  muscle1  is  situated  exterior  to  the  cavity  of 
the  pelvis,  and  arises  from  the  borders  of  the  obturator  foramen  and 
from  the  obturator  membrane.  Converging  to  a  tendon,  it  passes  behind 
the  neck  of  the  femur  to  be  inserted  into  the  trochanteric  fossa. 

The  Pyr'iform  muscle2  arises  within  the  pelvis  from  the  front  surface 
of  the  second,  third,  and  fourth  divisions  of  the  sacrum,  and  from  the 
lower  part  of  the  sacro-iliac  symphysis.  Passing  from  the  pelvis  through 
the  greater  sacro-ischiatic  foramen,  it  converges,  to  be  inserted,  by  a  round 
tendon,  into  the  greater  trochanter,  beneath  the  small  gluteal  muscle. 

The  Internal  Obturator  muscle3  arises  within  the  cavity  of  the  pelvis 
from  the  border  of  the  obturator  foramen  and  from  the  obturator  mem- 
brane. Converging  to  a  tendon,  it  passes  through  the  lesser  sacro-ischi- 
atic foramen  to  be  inserted  into  the  trochanteric  fossa. 

The  lesser  ischiatic  notch,  upon  which  the  tendon  plays  in  the  action 
of  the  muscle,  is  faced  with  fibro-cartilage,  and  furnished  with  a  synovial 
bursa  to  facilitate  movement. 

The  Gem'inous  muscle4  envelops  the  tendon  of  the  preceding  muscle, 
and  consists  of  a  pair  of  accessory  fleshy  fasciculi  to  it,  usually  described 
as  two  distinct  muscles.5  It  arises  from  the  spine  and  back  part  of  the 
tuberosity  of  the  ischium,  and  after  including  the  tendon  of  the  internal 
obturator  muscle,  is  inserted  in  company  with  it  into  the  trochanteric  fossa. 

The  Quadrate  Fem'oral  muscle6  arises  from  the  outer  border  of  the 
tuberosity  of  the  ischium,  and  proceeds  outwardly  to  be  inserted  into  the 
rough  line  descending  from  the  greater  trochanter. 

The  gluteal  muscles,  accordingly  as  they  act  from  their  origin  or  inser- 
tion, are  abductors  of  the  thighs,  or  they  fix  the  pelvis,  and  with  it  the 
trunk  upon  the  lower  extremities.  They  also  rotate  the  thighs  outwardly, 

1  M.  obturator,  or  obturatorius  exter-  *  M.  geminus,  or  gemellus ;  m.  gemini, 
nus ;   m.  sub-pubio-trochantereus  exter-  or   gemelli ;    marsupium   carneum ;    m. 
nus ;     m.    extra-pelvio-pubio-trochante-  marsupialis ;    m.  ischio-spini-trochante- 
reus.  reus  ;  m.  canaliculatatus  ;  m.  accessories 

2  M.  pyriformis  ;   m.  pyramidalis ;  m.  obturatoris  interni. 

p.    femoris :    m.    iliacus    externus ;    m.  6  M.  geminus,    or   gemellus   superior 

sacro-trochantereus ;  m.  primus  et  supe-  and   inferior ;    m.  secundus    et    tertius 

rior  quadrigeminus.  quadrigeminus. 

3  M.  obturator,  or  obturatorius  inter-  6  M.  quadratus  femoris ;  m.  tubei*-is- 
nus ;    m.  sub-pubio-trochantereus  inter-  chio-trochantereus ;     m.    ischio-subtro- 
nus  ;    m.  marsupialis ;    m.  bursalis ;   m.  chantereus  ;  m.  quartus    quadrigeminus 
intro-pelvio-trochantereus.  quadratus. 


THE   MUSCULAR  SYSTEM.  247 

into  action.     The  obturator,  pyriform,  geminous,  and  quadrate  femoral 
muscles  rotate  the  thighs  outwardly. 

THE  ILIAC  FASCIA. 

The  Il'iac  fas'cia1  invests  the  iliac  and  psoas  muscles,  and  is  a  con- 
tinuation of  the  same  fibrous  membrane,  constituting  in  other  positions 
the  transverse  and  pelvic  fascia.  It  adheres  to  the  lumbar  fascia,  the 
arcuate  ligaments,  the  vertebral  column,  the  crest  of  the  ilium,  Poupart's 
ligament,  and  the  pubis.  Together  with  the  transverse  and  pelvic  fascia 
it  converges  to  become  the  sheath  of  the  femoral  blood-vessels. 

MUSCLES  OF  THE  ILIAC   KEGION  AND  LOIN. 

The  Il'iac  muscle2  arises  from  the  corresponding  fossa  of  the  ilium,  and 
converges  to  the  femoral  arch,  under  which  it  passes  to  be  inserted,  in  con- 
junction with  the  psoas  muscle,  into  the  smaller  trochanter  of  the  femur. 

The  Pso'as  muscle3  arises  from  the  sides  of  the  bodies  and  transverse 
processes  of  the  last  dorsal  and  the  lumbar  vertebrae,  and  the  interme- 
diate intervertebral  disks.  Descending  from  the  loins  along  the  brim  of 
the  pelvis,  it  passes  under  the  femoral  arch  and  terminates  in  a  tendon, 
which,  being  joined  by  the  preceding  muscle,  is  inserted  into  the  back 
part  of  the  smaller  trochanter. 

The 'upper  extremity  of  the  muscle  has  the  internal  arcuate  ligament 
of  the  diaphragm  extended  across  it.  At  the  origin  from  the  sides  of 
the  vertebrae,  tendinous  arches  separate  it  from  the  lumbar  arteries  and 
veins  and  the  anastomotic  filaments  of  the  sympathetic  nerve.  Between 
the  tendon  of  insertion  and  the  smaller  trochanter,  a  synovial  bursa  is 
interposed. 

Occasionally,  a  Small  Pso'as  muscle*  is  situated  in  front  of  the  for- 
mer. It  arises  from  the  sides  of  the  bodies  of  the  upper  two  lumbar  ver- 
tebrae, and  terminates  in  a  thin  tendon,  which  expands  at  the  brim  of  the 
pelvis  into  the  iliac  fascia,  and  is  connected  with  the  ilio-pubic  eminence. 

The  iliac  and  psoas  muscles,  according  to  the  fixation  of  their  origin 
or  insertion,  bend  either  the  trunk  or  the  lower  extremities  forward. 
They  also  rotate  the  thighs  outwardly,  by  drawing  the  smaller  trochanter 
forward.  In  conjunction  with  the  gluteal  muscles  they  maintain  the 
erect  condition  of  the  body. 

1  Fascia  iliaca.  3  Greater  psoas  muscle  ;   m.  psoas  ma- 

2  M.  iliacus ;  internal  iliac  muscle;  m.  jor;  m.  lumbalis;  m.  praelumbo-trochan- 
iliacus  internus ;    m.  ilio-trochantereus ;  tereus  ;  part  of  the  m.  flexor  femoris  ;  m. 
part  of  the  m.  flexor  femoris ;  m.  femur  femur  moventium  sextus. 
moventium  septimus.  *  M.  psoas    parous ;    m.  prae-lumbo- 

pubius. 


248 


THE   MUSCULAR   SYSTEM. 


MUSCLES  ON  THE  FRONT  OF  THE  THIGH. 


FIG.  173. 


The  Ten'sor  of  the  Fern/oral  Fas'cia1  is  a  short,  flat  muscle,  situated 
at  the  upper  and  outer  part  of  the  thigh,  and 
inclosed  in  a  sheath  of  the  femoral  fascia.  It 
arises  from  the  anterior  superior  spinous  process 
of  the  ilium,  between  the  sartorius  and  gluteal 
muscles,  and  descends  in  front  of  the  greater 
trochanter,  to  terminate  in  the  femoral  fascia, 
*  a  short  distance  below  the  latter. 

The  Sarto'rius  muscle2  arises  tendinously 
from  the  anterior  superior  spinous  process  of 
the  ilium,  and  in  the  form  of  a  long  fleshy 
band  descends  obliquely  across  the  thigh  to  the 
inner  side  of  the  knee,  where  it  terminates  in  a 
tendon,  which  expands  to  be  inserted  on  the 
inner  side  of  the  tibia,  just  beiow  its  tuberosity. 

The  tendon  of  insertion  gives  off  a  process 
to  the  crural  fascia,  and  between  it  and  the 
tendon  of  the  succeeding  muscle  a  synovial 
bursa  is  interposed. 

The  sartorius  flexes  the  leg  upon  the  thigh, 
and  if  it  continues  its  action  the  leg  is  drawn 
.  across  the  opposite  thigh. 

The  Grrac'ilis  muscle3  arises  by  a  thin  apo- 
neurosis  from  the  margin  of  the  symphysis  and 
descending  ramus  of  the  pubis.  In  the  form 
of  a  long  fleshy  band  it  passes  down  on  the  in- 
ner part  of  the  thigh,  and  terminates  at  the 
knee  in  a  narrow  tendon,  which  expands  to  be 
inserted  beneath  the  sartorius  tendon.  Between 
its  tendon  and  the  tibia  a  synovial  bursa  is 
placed. 

The  gracilis  adducts  the  thigh,  and  assists 
the  action  of  the  preceding  muscle. 


MUSCLES  OF  THE  ILIAC  REGION  AND 

FRONT  OF  THE  THIGH.    1,  CFCSt  of  the 

ilium ;  2,  anterior  superior  spinous 
process :  3,  middle  gluteal  muscle ; 
4,  tensor  of  the  femoral  fascia;  5, 
sartorius;  6,  rectus;  7,  external 
vastus ;  8,  internal  vastus ;  9,  inser- 
tion of  the  quadriceps  extensor  into 
the  patella;  10,  iliac  muscle;  11, 
psoas  muscle;  12,  pectineal  muscle; 
13,  long  adductor ;  14,  great  adduc- 
tor; 15,  gracilis  muscle. 


1  M.  tensor  vaginae  femoris ;  m.  t.  fas- 
ciae latse  ;  m.  fasciae  latse  ;  m.  mernbra- 
nosus ;  m.  fascialis ;  m.  aponeurosis ;  m. 
ilio-aponeurosi  femoralis. 


2  M.   sartorius ;    m.   fascialis ;    m.  f. 
longus ;     m.   longissimus    femoris ;     m. 
cristo-tibialis ;  m.  ilio-prae-tibialis. 

3  M.  gracilis,   or    rectus    internus,  or 
interior;  m.  pubio-prae  tibialie. 


THE   MUSCULAR   SYSTEM.  249 

The  Quad'riceps  Exten'sor1  occupies  the  whole  front  and  sides  of  the 
thigh,  and,  as  implied  by  its  name,  has  four  heads  of  origin,  called  the 
rectus,  the  external  and  internal  vastus,  and  the  cruralis. 

The  Rec'tus2  arises,  by  two  short  thick  tendons,  from  the  anterior  infe- 
rior spinous  process  of  the  ilium  and  the  summit  of  the  acetabulum. 
Descending  in  front  of  the  thigh,  its  fleshy  fasciculi  form  a  penniform 
belly  ending  in  a  stout,  flat  tendon,  which  is  joined  by  the  tendons  of  the 
other  heads  of  the  quadriceps,  just  above  the  knee.  The  remaining 
three  heads,  more  intimately  associated  with  one  another  than  with  the 
rectus,  are  sometimes  described  as  a  distinct  muscle.3 

The  External  Vas'tus,4  the  largest  portion  of  the  quadriceps," arises  by 
an  aponeurosis  from  the  base  of  the  greater  trochanter  and  from  the 
outer  border  of  the  asperous  ridge.  The  Internal  Vas'tus5  arises  from 
the  inner  border  of  the  asperous  ridge ;  and  the  Crura'lis6  arises  from 
the  front  of  the  femur,  between  the  two  preceding  heads  of  the  quad- 
riceps. The  fleshy  fasciculi  of  the  internal  and  external  vastus  pro- 
ceed downward  and  forward,  those  of  the  cruralis  proceed  directly  down- 
ward, and  all  together  terminate  in  a  broad  tendon,  which  conjoins  with 
that  of  the  rectus  to  be  inserted  into  the  base,  sides,  and  front  of  the 
patella. 

Yiewing  the  ligament  of  the  patella  as  a  continuation  of  the  tendon 
of  the  quadriceps,  this  is  then  inserted  into  the  tuberosity  of  the  tibia. 

The  quadriceps  extends  the  leg  upon  the  thigh.  Some  detached  fas- 
ciculi7 of  the  muscle  descend  from  the  lower  part  of  the  femur  to  the 
synovial  capsule  of  the  knee  joint,  and  serve  to  retain  this  capsule  in  its 
proper  position. 

The  Pectine'al  muscle8  arises  from  the  horizontal  ramus  of  the  pubis, 
between  its  spine  and  the  ilio-pectineal  eminence,  and  descends  on  the 
inner  side  of  the  femur  to  be  inserted  into  the  line  leading  from  the 
smaller  trochanter  to  the  asperous  ridge. 

The  Long  Adduc'tor,9  situated  on  the  same  plane  as  the  former 
muscle,  arises  tendinously  from  the  front  of  the  pubis,  and  descends 

1  M.  quadriceps  extensor  cruris.  6  M.  vastus  medius ;   m.  venter  poste- 

2  M.  rectus  femoris ;  m.  rectus,  or  gra-       rior ;  m.  cruraeus. 

cilus  anterior,  or  cruris ;  m.  ilio-rotuleus ;  7  M.  subcrureus,   or  subcruralis ;    m. 

anterior  straight  muscle.  articulares  genu. 

3  M.  triceps  extensor  cruris ;  m.  femo-  8  M.  pectineus,  or  pectinalis ;    m.  pu- 
ralis,  or  cruralis ;  m.  trifemoro-rotuleus,  bio-femoralis ;  m.  lividus. 

or  tibio-rotuleus.  »  M.  adductor  longus  ;    m.  a.  femoris 

*  M.  vastus,  or  venter  externus.  primus  ;  caput  longum  m.  ad.  tricipitis ; 

5  M.  vastus,  or  venter  interims.  m.  ad.  primus ;  m.  pubio-femoralis. 


250  THE   MUSCULAR  SYSTEM. 

obliquely  to  be  inserted  into  the  middle  third  of  the  asperous  ridge  of 
the  femur. 

The  Short  Adduc'tor,1  concealed  by  the  preceding  two  muscles,  arises 
from  the  body  and  descending  ramus  of  the  pubis,  and  descends  ob- 
liquely to  be  inserted  into  the  upper  third  of  the  asperous  ridge  of  the 
femur. 

The  Great  Adduc'tor2  is  a  large,  triangular  muscle,  forming  a  parti- 
tion between  the  front  and  back  part  of  the  thigh.  It  arises  from  the 
descending  ramus  of  the  pubis  and  the  ramus  and  tuberosity  of  the 
ischium,  and  radiates  outward  and  downward  to  be  inserted  tendinously 
into  the  whole  length  of  the  asperous  ridge  of  the  femur,  extending  also 
by  a  tendinous  cord  to  the  internal  condyle. 

The  lower  third  of  the  insertion  of  the  great  adductor  is  perforated 
for  the  passage  of  the  femoral  blood-vessels ;  besides  which  there  are 
several  smaller  openings  in  the  tendinous  insertion  of  this  muscle  for  the 
transmission  of  the  perforating  arteries  and  their  companion  veins. 

The  pectineal  and  adductor  muscles  bend  the  thigh  on  the  pelvis, 
rotate  it  outwardly,  and  act  as  powerful  adductors. 

MUSCLES  ON  THE  BACK  OF  THE  THIGH. 

The  Bi'ceps  Flex'or,3  as  expressed  by  the  name,  arises  by  two  heads. 
The  long  head  arises  by  a  tendon,  common  to  it  and  the  semitendinous 
muscle,  from  the  back  part  of  the  tuberosity  of  the  ischium ;  the  short 
head  arises  from  the  lower  two-thirds  externally  of  the  asperous  ridge  of 
the  femur.  The  fleshy  fasciculi  terminate  in  an  aponeurosis  narrowing 
into  a  stout  tendon,  which  is  inserted  into  the  head  of  the  fibula.  From 
the  tendon  of  insertion  proceed  two  processes,  of  which  one  is  inserted 
into  the  head  of  the  JilfTa,  and  the  other  is  continuous  with  the  crural 
fascia. 


v 


The  Semiten'dinous  muscle4  arises,  in  common  with  the  tendon  of  the 
long  head  of  the  biceps  flexor,  from  the  tuberosity  of  the  ischium,  and 
descends  upon  the  inner  back  part  of  the  thigh.  Just  below  the  middle 
of  the  latter  its  fleshy  belly  ends  in  a  long  tendon,  which  proceeds  to  be 

1  M.  adductor   brevis;    m.  a.  femoris       culi  adductoris  tricipitis ;  m.  ischio-femo- 
secundus  ;  caput  breve  m.  ad.  tricipitis  ;       ralis. 

m.  ad.  secundus ;  m.  subpubio-femoralis.  3  M.  biceps  femoris,  or  flexor  cruris  ; 

2  M.  adductor  magnus ;  m.  a.  femoris       m.  ischio-femoro-peronealis. 

tertius  et  quartus;  caput  magnum  mus-          4  M.  semitendinosus ;    m.  ischio-praa- 

tibialis;  m.  seminervosus. 


THE   MUSCULAR   SYSTEM. 


251 


inserted  into  the  inner  side  of  the  tibia  below  its  tuberosity  and  beneath 
the  insertion  of  the  gracilis  tendon 


FIG.  174. 


The  semitendinous,  gracilis,  and  sartorius  muscles  arise  from  remote 
and  nearly  equidistant  points  of 
the  hip  bone,  and  converge  to  be 
inserted  into  the  same  point  of  the 
tibia.  Acting  together,  they  cross 
the  leg  upon  the  opposite  thigh. 

The  Semimem'branous  muscle,1 
situated  on  the  inner  side  of  the 
preceding  muscle,  arises  from  the 
back  part  of  the  tuberosity  of  the 
ischium  by  a  broad  tendon,  which 
expands  into  an  aponeurosis.  From 
this  a  fleshy  belly,  composed  of 
short  fasciculi,  proceeds  to  another 
aponeurosis  narrowing  into  a  cord- 
like  tendon,  which  is  inserted  into 
the  inner  side  of  the  head  of  the 
tibia.  The  tendon  of  insertion 
gives  off  processes  to  the  back  part 
of  the  capsular  ligament  of  the 
knee  joint  and  the  fascia  investing 
the  popliteal  muscle. 

The  biceps  flexor,  semitendinous, 
and  semimembranous  muscles  are 
all  flexors  of  the  leg  upon  the 
thigh.  The  tendon  of  insertion  of 
the  biceps  is  named  the  outer  ham 
string ;  the  corresponding  tendons 
of  the  semitendinous  and  semi- 
membranous  muscles,  the  inner 
ham  strings,  The  space  included 
by  the  ham  strings  is  the  poplite'al  region2  or  the  ham. 

1  M.  semimembranosus ;  m.  ischio-poplito-tibialis. 

2  Popliteal  fossa;  fossa  genu;   hock;  hoff;  garetum;  ignys;  suffrago;  hollow  of 
the  knee. 


MCSCLES  OF  THE  BACK  OF  THE  RIGHT   BUTTOCK  AND 

THIGH.  1,  middle  gluteal  muscle;  2,  great  gluteal 
muscle;  3,  external  vastus,  covered  by  the  femoral 
fascia;  4,  long  head  of  the  biceps  flexor;  5,  its 
short  head ;  6,  semitendinous,  and  7,  semimembran- 
oxis  muscles ;  8,  gracilis  muscle ;  9,  inner  border  of 
the  great  adductor;  10,  lower  extremity  of  the  sar- 
torius muscle;  11,  popliteal  space;  12,  gastrocne- 
mius  muscle. 


252 


THE    MUSCULAR   SYSTEM. 


MUSCLES  OF  THE  FRONT  AND  OUTER  PART  OF  THE  LEG,  AND 
UPPER  PART  OF  THE  FOOT. 

The  Anterior  Tib'ial  muscle1  arises  from  the  upper  two-thirds  of  the 
FlG  175  outer  part  of  the  tibia,  from  the  in- 

terosseous  membrane  and  the  crural 
fascia.  Its  fleshy  belly  descends 
the  leg  and  ends  in  a  flat  tendon, 
which  passes  beneath  the  annular 
ligament  of  the  ankle  to  the  inner 
side  of  the  foot,  where  it  is  inserted 
into  the  internal  cuneiform  bone 
and  the  base  of  the  metatarsal  bone 
of  the  great  toe.  This  muscle  flexes 
the  foot. 

The  Long  Exten'sor  of  the  Toes2 
arises  from  the  head  of  the  tibia, 
the  upper  three-fourths  of  the 
length  of  the  fibula,  and  from  the 
interosseous  membrane  and  crural 
fascia.  Its  fleshy  fasciculi  termin- 
ate in  a  tendon,  which  descends 
beneath  the  annular  ligament  of 
the  ankle  and  divides  into  four 
tendons  diverging  to  the  four  lesser 
toes,  over  the  backs  of  which  they 
expand  in  the  manner  of  the  ex- 
tensor tendons  of  the  fingers. 


MUSCLES  OF  THE  FRONT  OF  THE  LEG  AND  BACK  OP 
THE  FOOT.  1,  tendon  of  the  rectus  muscle  of  the 
thigh ;  2,  subcutaneous  inner  surface  of  the  tibia ; 
3,  anterior  tibial  muscle;  4,  long  extensor  «f  the 
toes;  5,  long  extensor  of  the  great  toe;  6,  anterior 
peroneal  muscle ;  7,  long  peroneal  muscle ;  8,  short 
peroneal  muscle ;  9,  borders  of  the  soleus ;  10,  bor- 
der of  the  inner  belly  of  the  gastrocnemius ;  11, 
short  flexor  of  the  toes,  beneath  the  tendons  of 
the  long  flexor. 

This  muscle  aids  the  anterior  tibial 


The  Anterior  Perone'al  muscle3 
arises  from  the  fibula,  below  the 
preceding,  and  ends  in  a  tendon, 
which  descends  beneath  the  annu- 
lar ligament  to  be  inserted  into  the 
base  of  the  last  metatarsal  bone, 
in  flexing  the  foot. 


1  M.  tibialis  anticus ;  m.  flexor  tarsi- 
tibialis;  m.  tibio-supertarseus ;  m.  tibio- 
supra-metatarseus  ;  m.  hippicus  ;  m.  ca- 
tenae. 


2  M.  extensor  longus,  or  communis  di- 
gitorum  pedis ;  m.  cnemodactylgeus. 

3  M.  peroneus  anticus,  or  tertius ;  m. 
tarsi-fibularis ;    m.  pereneo-supra-meta- 
tarseus  brevis ;  m.  nonus  Vesalii. 


THE    MUSCULAR   SYSTEM.  253 

The  Extender  of  the  Great  Toe1  lies  between  the  anterior  tibial  and 
long  extensor  muscles.  It  arises  from  the  lower  two-thirds  of  the  fibula 
and  the  interosseous  membrane,  and  ends  in  a  flat  tendon,  which  descends 
beneath  the  annular  ligament  of  the  ankle  and  expands  on  the  back  of 
the  great  toe,  being  finally  inserted  into  its  last  phalanx. 

The  Short  Extensor  of  the  Toes2  is  situated  on  the  back  of  the  foot. 
It  arises  from  the  outer  side  of  the  calcaneum  and  the  annular  ligament 
of  the  ankle,  and  forms  four  fleshy  bellies,  each  of  which  ends  in  a  ten- 
don proceeding  to  join  the  extensor  tendons  of  the  great  toe  and  the 
succeeding  three  toes. 

The  Long  Perone'al  muscle,3  situated  at  the  outer  part  of  the  leg, 
arises  from  the  upper  two-thirds  of  the  fibula,  from  the  contiguous  inter- 
muscular  partitions  and  the  crural  fascia.  Its  fleshy  belly  ends  in  a  long 
tendon,  which  descends  through  a  groove  at  the  back  of  the  external 
ankle,  then  proceeds  along  another  groove  on  the  outer  surface  of  the 
calcaneum,  and  turns  beneath  the  sole  of  the  foot.  Entering  the  groove 
of  the  cuboid  bone,  it  passes  obliquely  forward  and  inward  to  be  inserted 
into  the  base  of  the  first  metatarsal  bone. 

In  the  course  of  the  tendon,  it  twice  changes  its  direction;  once  at 
the  lower  end  of  the  fibula,  and  again  at  the  cuboid  bone.  In  these 
positions  it  acquires  a  thickened  fibro-eartilagmous  character,  and  at  the 
turn  of  the  cuboid  bone  not  unfrequently  has  a  sesamoid  bone  devel- 
oped in  it.  The  grooves  behind  the  external  ankle  and  the  outer  face 
of  the  calcaneum,  through  which  the  tendons  pass,  are  converted  by 
fibrous  bands  into  canals  lined  with  synovial  bursas.  The  groove  of  the 
cuboid  bone  is  converted  into  a  canal  by  the  long  plantar  ligament,  and 
is  likewise  provided  with  a  synovial  bursa. 

The  Short  Perone'al  muscle4  arises  from  the  lower  half  of  the  outer 
surface  of  the  fibula,  and  the  contiguous  intermuscular  partitions.  Its 
fleshy  belly  terminates  in  a  tendon,  which  descends,  in  company  with  that 
of  the  preceding  muscle,  behind  the  external  ankle,  and  passes  along  the 
outer  surface  of  the  calcaneum  to  be  inserted  into  the  base  of  the  last 
metatarsal  bone. 

The  long  and  short  peroneal  muscles  extend  the  foot,  and  are  the 
antagonists  of  the  anterior  peroneal  and  tibial  muscles. 

1  M.  extensor  proprius  pollicis,  or  hal-  or  maximus ;  m.  pereneo-sub-tarseus  ; 

lucis  ;  m.  e.  longus  hallucis.  m.  extensor  tarsi-fibularis  longior. 

•  M.  extensor  brevis  digitorum  pedis ;  4  M.  peroneus  brevis,  secundus,  or 

111.  pedicus.  medius  ;  m.  semifibulaeus  ;  m.  extensor 

3  M.  peroneus  longus,  primus,  posticus,  tarsi-fibularis  brevior. 


254 


THE   MUSCULAR   SYSTEM. 


FIG.  176. 


MUSCLES  ON  THE  BACK  OF  THE  LEG. 

The  Tri'ceps  Su'ral  muscle,1  as  expressed  in  the  name,  has  three  heads, 
the  fleshy  bellies  of  which  form  the  calf  of  the  leg.2     Two  of  the  bellies 
are  superficial,  and  constitute  the  gastrocne- 
mius  muscle,  while  the  third  is  under  cover  of 
the  former,  and  is  named  the  soleus  muscle. 

The  Gastrocne'mius  muscle3  arises  tendin- 
ously  just  above  the  condyles  of  the  femur; 
and  its  two  fleshy  bellies  descend  in  contact 
with  each  other  to  terminate  in  a  strong  apo- 
neurosis. 

The  Sole'us  muscle4  arises  from  the  head  and 
half  the  length  of  the  fibula,  from  the  oblique 
line  of  the  tibia  just  below  the  popliteal  mus- 
cle, and  from  the  inner  border  of  the  tibia  for 
several  inches  below  the  latter.  From  this 
origin  the  fleshy  fasciculi  descend  obliquely, 
and  terminate  in  an  aponeurosis  facing  the 
muscle  posteriorly. 

The  aponeuroses  of 
the  gastrocnemius  and 
soleus  muscles  conjoin 
in  the  formation  of  the 
strongest  cord-like  ten- 
don of  the  body,  named 
the  tendon  of  Achilles,5 
which  descends  to  be 
inserted  into  the  lower 
part  of  the  tuberosity 
of  the  calcaneum.  Between  the  upper  part  of  the  tuberosity  and  the 
tendon  a  synovial  bursa  is  interposed. 

The.  triceps  sural  muscle  by  drawing  on  the  calcaneum  elevates  the 
body  upon  the  toes,  as  in  walking.  Dancing,  jumping,  or  other  active 
movements  of  the  kind  tend  greatly  to  increase  its  size. 


SUPERFICIAL  MUSCLES  ON  THE 

BACK  OF  THE  RIGHT  LEG.     1,  bi- 

ceps  flexor;  2,  tendons  of  the 
Bemitendinous,  semimembra- 
nous,  gracilis,  and  sartorius 
muscles;  3,  popliteal  space;  4, 
gastrocnemius;  5,  eoleus;  6, 
tendon  of  Achilles;  7,  calca- 
neum ;  8,  tendons  of  the  long 
and  short  peroneal  muscles 
passing  behind  the  outer  an- 
kle ;  9,  tendons  of  the  posterior 
tibial  muscle  and  long  flexor 
of  the  toes  passing  behind  the 
inner  ankle. 


1  M.  extensor  pedis  ;  m.  triceps  surae  ; 
m.  surae,  or  suralis ;    m.  extensor  tarsi 
magnus. 

2  Sura ;  gastrocnemium. 

3  M.  gastrocnemius  externus ;   m.  ge- 
mellus  surae ;  m.  gemellus  externus  and 
internus ;  m.  bi-femoro-calcaneus. 


4  M.  gastrocnemius  internus ;  m.  tibio- 
calcaneus ;  m.  tibio-pereneo-calcaneus. 

5  Tendo   Achilles  ;    Achilles'    tendon  ; 
chorda,    or    funis    Hippocratis ;     corda 
magna ;  nervus  latus. 


THE   MUSCULAR   SYSTEM. 


255 


The  Plantar  muscle1  arises  from  the  femur  just  above  the  outer  con- 
dyle,  and  from  the  contiguous  portion  of  the  capsular  ligament  of  the 
knee  joint.  Its  short,  fleshy  belly  ends  in  a  long,  delicate  tendon,  which, 
after  passing  between  the  gastrocnemius  and  soleus  muscles,  descends  at 
the  inner  margin  of  the  tendon  of  Achilles  to  be  inserted,  in  company 
with  it,  into  the  calcaneum. 

This  muscle  corresponds  to  the  long  palmar  muscle  of  the  forearm, 
but  it  is  only  in  some  of  the  lower  animals  tha^jts  tendon  joins  the  plan- 
tar aponeurosis. 


FIG.  177. 


The  Poplite'al  muscle2  is  situated  immediately  below  the  knee  joint 
posteriorly,  and  is  invested  with  a  thin  aponeurosis 
connected  with  the  tendon  of  the  semimembranous 
muscle.  It  arises  by  a  tendon  from  the  groove  on 
the  outer  side  of  the  external  condyle  of  the  femur, 
beneath  the  contiguous  lateral  ligament  of  the  knee 
joint,  and  expands  upon  the  triangular  surface  at 
the  upper  part  of  the  tibia,  into  which  it  is  inserted. 

The  tendon  of  origin  is  attached  to  the  external 
semilunar  nbro-cartilage,  and  is  invested   by  the 
synovial  membrane  of  the 
knee  joint. 

The  popliteal  muscle 
flexes  the  leg  and  rotates 
it  inwardly. 


DEEP  MUSCLES  OF  THE  BACK  OF  THE 
LEG.  1,  femur ;  2,  posterior  portion 
of  the  capsular  ligament ;  3,  tendon 
of  the  semimembranous  muscle  in- 
serted into  the  head  of  the  tibia, 
and  giving  an  offset  to  the  capsular 
ligament;  4,  5,  internal  and  exter- 
nal lateral  ligaments;  6,  popliteal 
muscle ;  7,  long  flexor  of  the  toes ; 
8,  posterior  tibial  muscle;  9,  long 
flexor  of  the  great  toe ;  10, 11,  long 
and  short  peroneal  muscles;  12, 
tendon  of  Achilles;  13,  tendons  of 
the  long  flexor  of  the  toes,  and  the 
posterior  tibial  muscle,  just  before 
passing  beneath  the  internal  annu- 
lar ligament. 


The  Long  Flexor  of 
the  Toes,3  situated  under 
cover  of  the  muscles  of 
the  calf,  and  below  the 
popliteal  muscle,  arises 
from  the  tibia  to  within  a 
short  distance  of  its  lower 

extremity.     The  fleshy  fasciculi  proceed  obliquely 
to  a  tendon,  which  descends  behind  the  inner  ankle 
and  turns  beneath  the  concavity  of  the  calcaneum  into  the  sole  of  the 
foot.     Receiving  a  process  from  the  tendon  of  the  long  flexor  of  the 


1 M.  plantaris ;  m.  p.  gracilis ;  m.  exten- 
sor tarsi  minor ;  m.  gracilis  surse ;  m.  tibi- 
alis  gracilis ;  m.  femoro-calcaneus  brevis. 

2  M.  poplitaeus  ;  m.  sub-poplitaeus ;  m. 
femoro-popliti-tibialis. 


8  M.  flexor  longus  digitorum ;  m.  f.  1. 
d.  pedis  profundus  perforans ;  m.  flexor 
tertii  internodii  digitorum  pedis ;  m.  pe- 
ronodactylius. 


256  THE    MUSCULAR   SYSTEM. 

great  toe,  it  then  divides  into  four  tendons,  which  proceed  forward  and 
pass  through  perforations  in  the  tendons  of  the  short  flexor  of  the  toes, 
finally  to  be  inserted  into  the  bases  of  the  last  phalanges  of  the  four 
lesser  toes. 

The  Long  Flexor  of  the  Great  Toe,1  situated  at  the  outer  side  of  the 
preceding  muscle,  arises  from  the  lower  two-thirds  of  the  fibula,  and  ends 
in  a  tendon  which  descends  behind  the  inner  ankle  to  the  concavity  of 
the  calcaneum.  Turning  forward  in  the  sole  of  the  foot,  after  giving,  off 
a  process  to  the  tendon  of  the  long  flexor  of  the  toes,  it  proceeds  to  be 
inserted  into  the  base  of  the  last  phalanx  of  the  great  toe. 

The  Posterior  Tib'ial  muscle,2  situated  between  the  preceding  pair  of 
muscles,  arises  from  the  surface  of  the  interosseous  membrane  and  the 
contiguous  borders  of  the  tibia  and  fibula.  Its  fleshy  fasciculi  end  in  a 
tendon  which  descends  through  a  groove  behind  the  inner  ankle,  then 
proceeds  beneath  the  calcaneum  to  be  inserted  into  the  scaphoid  bone 
and  the  base  of  the  first  metatarsal  bone. 

This  muscle  is  an  extensor  of  the  foot. 


MUSCLES  OF  THE  SOLE  OF  THE  FOOT. 

The  Short  Flexor  of  the  Toes3  is  covered  by  the  middle  portion  of  the 
plantar  fascia,  from  which  and  the  inner  tubercle  of  the  calcaneum.  it  has 
its  origin.  Proceeding  forward,  it  terminates  in  four  tendons,  which, 
after  being  perforated  for  the  passage  of  the  tendons  of  the  long  flexor 
of  the  toes,  are  inserted  into  the  bases  of  the  second  phalanges  of  the 
latter. 

The  Accessory  Flexor4  arises  from  the  concavity  and  under  part  of 
the  calcaneum,  and  is  inserted  into  the  tendon  of  the  long  flexor  of  the 
great  toes,  to  which,  as  the  name  indicates,  it  is  an  accessory  head. 

The  Lumbrical  muscles5  are  four  fleshy  fasciculi  like  those  of  the 
hand.  They  arise  from  the  tendons  of  the  long  flexor  of  the  toes,  and 


1  M.  flexor  longus  pollicis  pedis ;    m.  perforates ;  m.  flexor  secundi  internodii 
f.  1.  hallucis  pedis.  digitorum  pedis. 

2  M.  tibialis  posticus;  m.  nauticus;  m.  4  M.  flexor  accessorius ;  m.  accessorius 
extensor  tarsi-tibialis ;  m.  tibio-sub-tar-  flexoris  longi  digitorura  pedis ;  massacar- 
seus.  nea  Jacobi  Sylvii;  caro  quadrata  Sylvii ; 

3  M.  flexor  brevis  digitorum  pedis  ;  m.  caro  accessoria ;  m.  plantarus  verus. 
f.  b.d.  p.  perforatus ;  m.  f.  sublimus  d.  p.  5  M.  lumbricales  pedis. 


THE   MUSCULAR   SYSTEM. 


257 


proceed  to  be  inserted  into  the  corresponding  extensor  tendons  and  the 
bases  of  the  first  phalanges  of  the  toes. 

The  Abduc'tor  of  the  Great  Toe,1  the  most  superficial  of  the  muscles 
on  the  inner  side  of  the  sole  of  the  foot,  arises  from  the  calcaneum,  the 
scaphoid  and  internal  cuneiform  bones,  and  the  plantar  fascia,  and  pro- 
ceeds forward  to  be  inserted  by  a  tendon  into  the  base  of  the  first 
phalanx  of  the  great  toe. 

FIG.  178.  FIG.  179. 


MUSCLES  OF  THE  SOLE  OF  THE  FOOT.  1,  calcaneum; 
2,  posterior  extremity  of  the  plantar  fascia;  3,  ab- 
ductor of  the  great  toe;  4,  abductor  of  the  little 
toe ;  5,  short  flexor  of  the  toes ;  6,  tendon  of  the 
long  flexor  of  the  great  toe;  7,  insertion  of  the 
lumbrical  muscles,  which  are  seen  to  the  right  of 
the  tendons  of  the  short  flexor  of  the  toes. 


DEEP  MUSCLES  OF  THE  SOLE.  1,  attachment  of  the 
plantar  fascia  and  short  flexor  of  the  toes ;  2,  ac- 
cessory flexor;  3,  tendon  of  the  long  flexor  of  the 
toes;  4,  tendon  of  the  long  flexor  of  the  great  toe; 
5,  two  heads  of  the  short  flexor  of  the  same ;  6,  ad- 
ductor of  the  great  toe;  7,  flexor  of  the  little  toe; 
8,  transverse  muscle ;  9,  interosseous  muscles ;  10, 
course  of  the  tendon  of  the  long  peroneal  muscle, 
seen  through  the  long  plantar  ligament. 

The  Short  Flexor  of  the  Great  Toe2  arises,  as  a  pair  of  fleshy  bellies, 
from  the  cuboid  and  outer  two  cuneiform  bones,  and  proceeds  forward 
to  be  inserted  tendinously  into  the  base  of  the  first  phalanx  of  the 
great  toe.  Between  the  two  bellies  of  this  muscle  lies  the  tendon  of  the 
long  flexor. 

The  Adduc'tor  of  the  Great  Toe3  arises  from  the  cuboid  bone  and  the 


1  M.  abductor  pollicis  pedis ;  m.  calco- 
sub-phalangeus  pollicis. 

2  M.  flexor  brevis  pollicis,  or  hallucis 
pedis. 


3  M.  adductor  pollicis,  or  hallucis  pe- 
dis ;  m.  antithenar ;  m.  metatarso-sub- 
phalangeus  pollicis. 


IT 


258  THE   MUSCULAR  SYSTEM. 

bases  of  the  third  and  fourth  metatarsal  bones,  and  is  inserted  tendinously 
into  the  base  of  the  first  phalanx  of  the  great  toe. 

The  Transverse  muscle1  consists  of  several  fasciculi  arising  from  the 
heads  of  the  second,  third,  and  fourth  metatarsal  bones,  and  inserted 
tendinously  into  the  base  of  the  first  phalanx  of  the  great  toe. 

The  sesamoid  bones  are  inclosed  within  the  insertion  of  the  muscles 
into  the  base  of  the  first  phalanx  of  the  great  toe,  and  move  upon  the 
head  of  the  metatarsal  bone  during  the  action  of  those  muscles. 

The  Abduc'tor  of  the  Little  Toe2  arises  from  the  outer  tubercle  of  the 
calcaneum,  the  plantar  fascia,  and  the  base  of  the  last  metatarsal  bone, 
and  proceeds  forward  to  be  inserted  into  the  base  of  the  first  phalanx  of 
the  little  toe. 

The  Flexor  of  the  Little  Toe 3  arises  from  the  long  plantar  ligament 
and  the  base  of  the  last  metatarsal  bone,  and  proceeds  to  be  inserted 
into  the  base  of  the  first  phalanx  of  the  little  toe. 

THE  INTEKOSSEOUS  MUSCLES  OF  THE  FOOT. 

The  Dorsal  Interos'seous  muscles  occupy  the  metatarsal  intervals,  with 
which  they  correspond  in  number.  They  arise  from  the  adjacent  sides 
of  the  metatarsal  bones,  and  are  inserted  tendinously  into  the  extensor 
tendons  and  bases  of  the  first  phalanges  of  the  middle  three  toes. 

The  first  dorsal  interosseous  muscle  is  inserted  on  the  inner  side  of  the 
second  toe,  and  acts  as  an  adductor ;  while  the  others  are  inserted  into 
the  outer  side  of  the  second,  third,  and  fourth  toes,  and  act  as  abductors. 

The  Plantar  Interos'seous  muscles,  three  in  number,  lie  on  the  outer 
three  metatarsal  bones  and  arise  from  their  inner  side,  from  whence  they 
proceed  forward  to  be  inserted  into  the  extensor  tendons  and  bases  of 
the  first  phalanges  of  the  corresponding  toes,  to  which  they  act  as  adduc- 
tors. 

1  M.  transversalis,  or  transversus  pe-  2  M.  abductor  minimi  digiti  pedis. 

dis ;  m.  scandularius ;  m.  metatarso-sub-          3  M.  flexor  minimi  digiti  pedis. 
phalangeus. 


CHAPTER  Y. 

ANATOMICAL    ELEMENTS   OF    SEROUS   AND    MUCOUS   MEMBRANES,    THE 
GLANDS,    THE   LUNGS,    AND   THE    SKIN. 


FIG.  180. 


SEROUS  and  mucous  membranes,  glands,  the  lungs,  and  the  skin  pos- 
sess common  anatomical  elements,  which  hold  the  same  relative  position 
with  one  another.  These  elements  are  as  follows :  a  cellular  layer,  a 
basement  membrane,  a  fibrous  layer,  and  blood-vessels,  lymphatics,  and 
nerves. 

The  Cellular  layer1  occupies  the  free  surface  of  the  structures  above 
mentioned,  and  is  named 
epithelium,2  except  on 
the  skin,  where  it  is  called 
epider'mis,  It  consists 
of  from  one  to  many 
layers  of  cells,  of  different 

forms  in  the  Various  StrUC-         DIAGRAM  EXHIBITING  THE  RELATIVE  POSITION  OF  THE  COMMON  ANA 

.  .       , .  ,          rp,  .  TOMICAL  ELEMENTS  OF  SEROUS  AND  MUCOUS   MEMBRANES,  THE  GLANDS 

LlCated.      ineepi-  THE  LUNGSj  ANJ)  THE  8KIN      1?  epithelium,  secreting  cells,  or  epi- 

thelium  Of  the  UriniferOUS  dermis,  as  the  case  may  be,  composed  of  nucleated  cells,  and  occu- 

,11  f     fVi         V'  1  Pying  the  free  surface  of  the  structure  mentioned;  2,  basement 

e^S  layer,  in  this  and  other  diagrams  purposely  represented  much 

presents   an  example  Of   a  thicker  than  natural,  in  comparison  with  the  other  layers;  :j. 

Invpr  of  pplls  •    thp  fit>rous  layer,  in  which  the  arteries  and  veins  (4)  terminate  in  a 


capillary  net-work. 

serous   membranes,   from 

one  to  four  layers ;  the  mucous  membrane  of  the  stomach,  several  layers 
in  different  stages  of  development;  the  mucous  membrane  of  the  mouth, 
many  layers;  and  the  epidermis,  above  all  similar  structures,  presents 
the  greatest  number  of  layers  of  cells. 

From  difference  in  form,   and  other  peculiarities,  the  epithelium  is 


1  Implying  its  composition  of  organic  cells,  and  not  to  be  confounded  with  areolar 
or  connective  tissue,  which,  until  within  a  comparatively  short  period,  was  called 
cellular  tissue. 

2  Epitelium ;  endepidermis. 


(259) 


260  EPITHELIUM. 

divided  into  the  following  varieties:  squamous  epithelium;  pavement 
epithelium ;  spheroidal,  polyhedral,  and  irregular  epithelium  ;  columnar 
epithelium  ;  and  ciliated  epithelium. 

The  Squa'mous  epithelium1  consists  of  many  layers  of  broad,  thin 
scales,  which  are  flattened  cells,  containing  a  nucleus  and  a  few  scattered 
coarse  granules.  This  variety  forms  the  epithelium  of  the  mucous 
membrane  of  the  mouth,  lower  part  of  the  pharynx,  oesophagus,  vagina, 
vulva,  entrance  of  the  urethra,  conjunctiva,  and  entrance  of  the  nose. 

FIG.  181.  Fia.  182. 


SQUAMOUS  EPITHELIUM,  consisting  of  nucleated  PAVEMENT  EPITHELIUM,  from  a  serous  membrane, 

cells  transformed  into  broad  scales.   From  the  mu-        highly  magnified,  and  seen  to  consist  of  flat,  six- 
cous  membrane  of  the  mouth,  highly  magnified.  sided  nucleated  cells. 

The  Pavement  epithelium2  consists  of  from  one  to  four  layers  of  flat 
nucleated  cells,  usually  six-sided,  and  regularly  arranged  like  the  blocks 
of  a  pavement,  whence  the  name.  Such  an  epithelium  forms  the  free 
surface  of  the  serous  membranes,  including  the  synovial  membranes  and 
the  lining  membrane  of  the  vascular  system ;  it  likewise  constitutes  the 
epithelium  of  the  uriniferous  tubules,  sweat  glands,  and  air-cells  of  the 
lungs. 

The  Spheroidal,  polyhedral,  and  irregular  epithelium  are  modifica- 
tions of  the  same  form.  The  spheroidal  epithelium  constitutes  the 
secreting  cells  of  the  salivary  glands  and  pancreas,  but  they  are  more  or 
less  modified  into  the  polyhedral  form  by  mutual  pressure.  The  secret- 
ing cells  of  the  liver  are  polyhedral,  but  more  or  less  irregular.  The 
epithelium  of  the  excretory  duct  of  the  kidney  and  of  the  bladder 
exhibits  singularly  irregular  forms  of  cells. 

The  Columnar  epithelium3  consists  of  a  single  layer  of  six-sided  col- 
umnar cells,  with  a  conical  prolongation.  The  broad  end  of  the  cells  is 
free,  the  sides  are  in  contact,  and  the  narrow  end  is  imbedded  in  a  pro- 
geny of  developing  cells.  The  columnar  cells  are  more  delicate  than 
most  other  kinds,  are  provided  with  granular  contents,  and  possess  a 
large  oval  nucleus.  Such  an  epithelium  is  found  on  the  mucous  mem- 

1  Scaly,    lamellar,    tabular,    flattened,  3  Cylinder,  prismatic,    conical,   or  tu- 
pavement,  or  tesselated  epithelium.                bular  epithelium ;  simple  columnar  epi- 

2  Tesselated  epithelium.  thelium. 


EPITHELIUM. 


261 


brane  of  the  stomach,  small  and  large  intestines ;  in  many  glands,  as  the 
tubular  glands  of  the  intestines ;  in  the  ducts  of  most  glands  ;  in  the 
gall-bladder ;  and  in  the  urethra. 


FIG.  183. 


FIG.  184. 


; 


POLYHEDRAL  EPITHELIUM,  exemplified  by  secret- 
ing cells  of  the  liver.  The  arrangement  is  ideal. 
1,  space  occupied  by  a  blood-vessel;  2,  isolated 
cells. 


DIAGRAM  OF  A  VERTICAL  SECTION  OF  MUCOUS  MEM- 
BRANE OF  THE  SMALL  INTESTINES,  highly  magnified. 
1,  fibrous  layer,  in  which  the  blood-vessels  are  dis- 
tributed; 2,  basement  membrane  ;  3,  young  nucle- 
ated cells ;  4,  layer  of  columnar  cells ;  5,  6,  cells  in 
the  act  of  being  shed  or  thrown  off;  7,  free  ends  of 
the  columnar  cells,  exhibiting  their  six-sided  form ; 
8,  a  single  columnar  cell,  exhibiting  its  actual  form 
at  all  parts 


The  Cil'iated  epithelium1  dif- 
fers from  the  preceding,  in  the  cells 
possessing  at  their  free  extremity  a 
number  of  exceedingly  fine  filament- 
ous appendages,  named,  from  their  resemblance  to  the  eyelashes,  cij'ia.2 
These  are  processes  of  the  cell  wall  of  uniform  size,  and  during  life  are 
endowed  with  the  power  of  rapidly  and  incessantly  moving  backward 
and  forward.  This  vibratory  movement  is  always  uniform  and  wave-like 
in  a  long  series  of  cells,  so  that  when  seen  over  a  surface  of  some  extent, 
it  reminds  one  of  the  movement  of  a  field  of  grain  under  the  influence 
of  a  gentle  breeze.  The  vibration  of  the  cilia  produces  currents  in  the 
liquids  in  contact  with  them,  and  thus  conveys  the  liquids  from  one  posi- 
tion to  another.  The  cil'iary  motion  even  continues  for  some  time  after 
the  cells  have  been  scraped  from  the  membrane  of  which  they  form  a 
part ;  and  the  resistance  of  the  liquid  to  the  vibrating  cilia  of  the  de- 
tached cells  causes  these  to  move  freely  about,  as  if  endowed  with  volun- 
tary power.  A  ciliated  epithelium  exists  on  the  mucous  membrane  of 
the  upper  part  of  the  nose  and  pharynx,  the  tympanum  and  Eustachian 
tube,  the  larynx,  trachea,  bronchi  and  their  ramifications,  and  the  cavity 
of  the  uterus  and  Fallopian  tubes. 

The  epidermis  will  be  particularly  described  in  the  account  of  the 
skin. 


1  Vibratile  epithelium. 


2  Vibratile  cilia;  vibrillse. 


262 


BASEMENT   MEMBRANE. 


FIG.  185. 


DIAGRAM  OF  A  VERTICAL  SECTION 
OF  THE  BRONCHIAL  MUCOUS  MEM- 
BRAXE,  highly  magnified.  1,  col- 
umnar ciliated  epithelial  cells;  2, 
cilia;  3,  nuclei;  4,  young  cells;  5, 
basement  membrane;  6,  fibrous 
layer. 

works  of  elastic  tissue. 


Basement  membrane1  is  a  thin,  homogeneous  layer,  or  one  devoid  of 
visible  structure,  supporting  the  cellular  layer  of  the  serous  and  mucous 
membranes,  the  skin,  and  other  organs  above 
mentioned ;  and  resolving  itself  beneath  into 
the  fibrous  layer.  In  some  instances  it  is  very 
distinct  and  readily  observed,  as  in  the  uriri- 
iferous  tubules;  in  others  it  certainly  exists, 
but  is  not  so  easily  demonstrable  as  in  the 
mucous  membranes  and  skin ;  and  in  some 
cases  it  is  so  difficult  to  detect,  that  in  such 
positions  by  many  its  existence  is  denied,  as 
in  the  liver. 

The  fibrous  layer,2  situated  beneath  and 
supporting  the  basement  membrane  and  epi- 
thelial  layer,  is  composed  of  an  intertexture  of 
bundles  of  fibrous  tissue  mingled  with  fine  net- 
This  layer,  for  the  most  part,  is  absent  in  the 
liver,  exists  in  very  small  quantity  in  the  kidneys,  is  well  developed  in 
other  glands,  and  in  the  serous  and  mucous  membranes,  and  reaches  its 
greatest  extent  in  the  formation  of  the  dermis.  The  fibrous  layer  gives 
strength  and  stability  to  the  other  structures,  and  in  it,  or  in  a  correspond- 
ing position  if  it  is  absent,  the  blood-vessels,  lymphatics,  and  nerves  are 
distributed,  and  never  penetrate  the  basement  membrane  or  epithelial 
layer.  The  blood-vessels  form  capillary  nets,  which  have  the  closest 
meshes  in  the  glands,  mucous  membranes,  lungs,  and  skin.  The  lym- 
phatics are  more  numerous  in  these  than  any  other  structures.  The  nerv- 
ous supply  is  also  abundant. 

Most  or  perhaps  all  the  structures,  whose  elements  have  been  described 
above,  lose  the  superficial  portion  of  their  cellular  layer  from  time  to 
time,  which  is  as  constantly  renewed.  The  process  is  not  very  evident 
in  the  cellular  layer  of  glands,  nor  is  it  much  more  clear  in  the  pave- 
ment epithelium  of  serous  membranes  and  allied  structures.  The  colum- 
nar epithelium,  including  its  ciliated  variety,  exhibits  strong  evidences  of 
the  process,  but  it  is  most  strikingly  obvious  in  the  squamous  epithelium 
and  the  epidermis. 

In  a  vertical  section  of  the  mucous  membrane  of  the  mouth,  the  cells 
of  the  epithelium  in  contact  with  the  basement  membrane  are  observed 
to  be  comparatively  soft,  polyhedral  from  mutual  pressure,  and  of  uniform 


1  Structureless,  or  amorphous  membrane ;  homogeneous  layer ;  membrana  inter- 
media, or  limitans ;  primary  or  limitary  membrane. 

2  Membrana  propria. 


SEROUS   MEMBRANES.  263 

diameters ;  the  layers  of  cells  in  succession  increase  in  breadth  at  the  ex- 
pense of  their  depth ;  and 
the  superficial  cells  form 
the  broad  thin  scales  char- 
acteristic of  the  squamous 
epithelium,  of  which  G 

shreds  or  flakes  are  con- 
stantly being  cast  off  while 
they  are  renewed  from  be- 
neath. 

j  ,.        -,  ,.  f  DIAGRAM  OP  A  SECTION  OF  THE  MUCOUS    MEMBRANE  OF  THE  MOUTH, 

L     highly  magnified.   1,  fibrous  layer,  in  which  the  blood-vessels  are 

the  muCOUS  membrane  Of  distributed;  2,  basement  layer;  3,  young  cells  of  the  epithelium; 
the  Small  intestine,  SeV-  4,  older  cells  transformed  into  scales;  5,  shred  of  epithelium  cast 

off;  6,  a  single  scale,  seen  on  its  broad  surface;  7,  a  similar  scale, 

eral  layers   of   cells   are    seen  in  its  thickness. 
observable,  in  the  deeper 

part  of  the  epithelium,  in  various  stages  of  development,  from  the  simple 
spheroidal  form  to  the  columnar  cells,  which  always  exist  in  a  single  layer 
at  the  free  surface  of  the  epithelium.  How,  or  whether  these  columnar 
epithelial  cells  are  shed,  has  not  been  positively  determined.  On  several 
occasions,  the  author,  in  some  examinations  of  the  structure  of  the  small 
intestine  in  the  lower  animals,  has  observed  isolated  columnar  cells  ap- 
parently crowded  from  their  position  by  pressure  laterally  and  beneath, 
as  represented  in  figure  184.  Perhaps  from  these  instances  we  may  not 
be  wrong  in  suspecting  that  the  older  or  effete  cells  are  thus  pushed 
one  after  another  from  their  place  by  the  more  vigorous  cells  around 
and  the  developing  ones  beneath. 

SEROUS  MEMBRANES. 

The  Serous  membranes,1  named  from  the  character  of  the  liquid 
bathing  their  free  surface,  line  cavities  of  the  body  having  no  exterior 
communication,  and  are  therefore  closed  sacs.  They  serve  to  lubricate 
organs  which  move  upon  one  another,  and  in  many  instances  form  folds, 
which  retain  the  organs  in  their  position,  and  from  this  circumstance,  in 
some  cases  are  named  ligaments,  as  in  the  case  of  the  suspensory  liga- 
ment of  the  liver. 

The  serous  membranes  are  as  follows  : — 

1.  The  two  pleurae  lining  the  sides  of  the  thorax  and  investing  the  lungs. 

2.  The  pericardium  surrounding  the  heart. 

3.  The  peritoneum  lining  the  cavity  of  the  abdomen  and  reflected  upon  its 
viscera. 

1  Membrause  serosae. 


264 


SEROUS    MEMBRANES. 


4.  The  vaginal  tunic  of  each  testicle. 

5.  The  arachnoid  membrane  of  the  brain  and  spinal  cord. 

6.  The  lining  membrane  of  the  ventricles  of  the  brain. 

7.  The  synovial  membranes  of  the  joints. 

8.  The  synovial  bursa3. 

9.  The  lining  membrane  of  the  vascular  system. 
\  JX).  The  lining  membrane  of  the  labyrinth. 

In  the  relation  of  the  serous  membranes  to  the  contiguous  parts,  one 
portion  is  applied  upon  the  interior  surface  of  the  cavity  it  lines,  and 
another  portion  is  reflected  upon  the  organ  or  organs  contained  within 
the  cavity.  The  former  is  named  its  parietal  or  lining  portion ;  the 
latter,  its  reflected  or  vis'ceral  portion,  From  this  arrangement,  the 
organs  are  not  contained  within  the  cavity  of  the  serous  sacs,  but  are 
excluded  by  the  membrane  being  reflected  over  them. 

The  outer  surface  of  the  serous  membrane  is  attached  to  the  neighbor- 
ing parts  by  connective  tissue,  named  from  its 
position  sub-serous  tissue ;  the  inner  surface  is 
free,  smooth,  shining,  and  moistened  with  a 
serous  liquid  elaborated  by  the  membrane 
itself.  The  free  surfaces  of  the  parietal  and 
reflected  portions  of  the  serous  membrane  come 
into  contact,  so  that  the  organs  easily  and 
smoothly  move  upon  one  another,  and  against 
the  walls  of  the  cavity  containing  them ;  the 
movement  being  facilitated  by  the  liquid  lubri- 
cating the  surfaces. 

The  liquid  of  the  serous  cavities  resembles 
the  serum  of  the   blood   in   appearance   and 


FIG.  187. 


only  attached  portion  of  the  organ, 
all  others  being  free ;  3,  side  of  the 
thorax;  4,  diaphragm;  5,  parietal 
pleura;  6,  pulmonary  or  reflected 
pleura ;  7,  cavity  of  the  pleura. 


DIAGRAM  EXHIBITING  THE  RELA- 
TION OP  A  SEROUS  MEMBRANE,  THE 
PLEURA,  TO  THE  ORGAN  IT  INVESTS 
AND  THE  CAVITY  IT  LINES.  1 ,  lung ;  ...  ,  ,  . 

2,  root  of  the  lung,  which  is  the  composition,  but  in  some  instances  is  more 
viscid,  as  in  the  case  of  that  of  the  synovial 
membranes. 

The  sub-serous  connective  tissue  usually  at- 
taches the  serous  membranes  closely  to  the 
adjacent  parts.  In  the  case  of  the  arachnoid  membrane  attached  to  the 
pia  mater,  it  consists  of  scattered  bands,  the  sub-arach/noid  tissue,  with 
the  intervals  occupied  by  a  liquid  like  that  contained  within  the  cavity 
of  the  arachnoid  membrane. 

When  serous  membranes  invest  the  interior  surface  of  fibrous  mem- 
branes, as  in  the  case  of  the  arachnoid  and  dura  mater,  and  the  serous 
and  fibrous  pericardium,  the  two  together  are  often  named  fibro-serous 
membranes. 

The  serous  membranes  are  thin,  transparent,  and  colorless,  moderately 


SEROUS   MEMBRANES.  265 

strong,  extensible  and  elastic.  In  structure  they  consist  of  one  or  more 
layers  of  pavement  epithelium  composed  of  six-sided  cells  ;  a  thin  base- 
ment membrane,  and  a  layer  of  fibrous  tissue  with  mingled  elastic  fibres. 
The  blood-vessels  are  comparatively  few,  and  form  capillary  nets,  with 
wide  meshes,  in  the  fibrous  layer.  Numerous  lymphatics  and  fine 
plexuses  of  nerves  also  pervade  the  latter,  though  the  serous  membranes 
are  quite  devoid  of  sensibility  in  a  condition  of  health.  The  liquid  of 
serous  membranes  consists  of  water,  with  from  one  to  six  percentage 
of  albumen,  chloride  of  sodium,  and  phosphate  of  soda  and  lime. 

Syno'vial  membranes1  line  the  interior  of  the  joints,  but  do  not  cover 
the  articular  cartilages.  Their  lubricating  liquid,  named  syno'via,2  is 
more  viscid  than  the  liquid  of  other  serous  membranes.  At  the  margin 
of  the  articulations  the  membrane  frequently  forms  one  or  more  folds 
containing  fat,  and  named  synovial  fringes.3  These  are  yellow  or  red- 
dish yellow,  more  vascular  than  other  portions  of  the  synovial  membrane, 
and  apparently  more  active  in  the  production  of  synovia. 

Syno'vial  bur'sae4  occur  where  muscles  or  tendons  move  upon  bones, 
fibro -cartilages,  or  ligaments,  or  frequently  upon  one  another.  In  many 
positions  they  appear  as  simple,  flattened  spheroidal  sacs,  tightly  adhe- 
rent by  one  side  to  the  moving  organ,  and  by  the  other  side  to  the  part 
against  which  the  organ  moves.  Instances  of  this  kind  are  seen  in  the 
bursa  beneath  the  deltoid  muscle,  and  that  between  the  insertion  of  the 
biceps  flexor  tendon  and  the  tuberosity  of  the  radius. 

When  tendons  move  through  grooves  of  bones,  or  beneath  annular  or 
vaginal  ligaments,  the  synovial  bursa5  lines  the  groove  or  canal  and  is 
thence  reflected  upon  the  tendons.  In  the  vicinity  of  joints  the  bursae 
often  communicate  with  their  cavity. 

In  positions  in  which  a  number  of  tendons  move  upon  one  another,  as 
in  the  case  of  the  flexor  tendons  in  the  vicinity  of  the  wrist,  a  highly 
extensible,  fibro-elastic  membrane6  is  folded  around  and  among  them, 
which  appears  to  have  the  same  function  as  the  synovial  bursaB,  but 
presents  no  trace  of  an  epithelium.  Beneath  the  skin  also  in  certain 
positions,  as  between  that  of  the  elbow  and  the  olecranon,  or  that  of 
the  knee  and  the  patella,  pouches7  exist,  apparently  of  the  nature  of 

1  Capsulae  synoviales.  4  Bursae  mucosae  ;    b.  m.  vesiculares ; 

2  Mucilago ;  humor,  unguentum,  smeg-  b.  or  capsulae  synoviales ;  sacci  mucosi ; 
ma,  axungia, gluten, or humidum nativum  synovial  crypts  or  follicles;  blennocys- 
articulorum;  hydrarthrus;  arthrohydrine.  tides ;  vesicrc  unguinosre  tendinum. 

3  Synovial  glands  of  Havers ;    Haver-  5  Vaginas  synoviales  or  mucilaginosae. 
sian  glands;  glandulae  articulares;  syno-  6  Bursae  mucosae  tendinosae. 

vial  fimbriae ;  plicae  synoviales,  adiposse,  »  B.  m.  subcutanese. 

or  vasculosae  ;  ligamenta  mucosa. 


266  MUCOUS   MEMBRANES. 

synovial  bursaa.     These  have  a  ragged-looking  internal  surface  devoid 
of  an  epithelium. 

MUCOUS  MEMBRANES. 

Mucous  membranes,  though  possessing  common  physical  or  anatomical 
elements,  like  the  serous  membranes,  differ  in  most  other  respects.  They 
line  internal  cavities  and  passages  communicating  with  the  exterior, 
together  with  various  receptacles  and  glandular  ducts  opening  on  the 
surfaces  of  the  former.  They  never  form  completely  closed  sacs,  as  the 
serous  membranes,  and  are  all  continuous  with  one  another  and  the  skin. 
Habitually  exposed  to  the  contact  of  materials  foreign  to  their  structure, 
such  as  food,  air,  dust,  the  secretions  and  excretions  of  glands,  their  free 
surface  is  bathed  with  a  viscous  liquid  named  mucus,  which  is  usually 
more  consistent  than  the  liquid  of  serous  membranes. 

Mucous  membrane  lines  the  cavity  of  the  nose  and  its  communicating 
sinuses,  the  front  of  the  eye  and  the  lachrymo-nasal  duct,  the  tympanum, 
mastoid  sinuses  and  Eustachian  tube,  the  mouth,  pharynx,  oesophagus, 
stomach,  and  intestines,  the  larynx,  trachea,  bronchi  and  their  ramifica- 
tions, the  salivary,  pancreatic,  and  bile  ducts,  and  the  gall-bladder,  the 
pelvis  of  the  kidneys,  ureters,  urinary  bladder  and  urethra,  the  semi- 
nal ducts  and  vesicles,  the  vagina,  uterus,  and  Fallopian  tubes,  and 
the  ducts  of  the  mammary  glands.  From  their  isolation,  all  these  mu- 
cous membranes  together  are  divided  into  three  groups,  generally  desig- 
nated as  the  gastro-pulmonary,  genito-urinary,  and  mammary  mucous 
membranes.  At  the  edges  of  the  eyelids,  nostrils,  mouth,  anus,  vulva, 
urethra,  and  orifices  of  the  milk  ducts,  the  mucous  membranes  become 
continuous  structures  with  the  skin. 

All  the  mucous  membranes  possess  a  free  surface  formed  of  an  epithe- 
lium resting  on  a  basement  membrane,  beneath  which  is  a  fibrous  layer 
adhering  to  the  contiguous  parts  by  connective  tissue,  named  from  its 
position  the  submucous  tissue.1  In  the  hollow  viscera  the  latter  forms 
an  abundant  and  distensible  layer,  permitting  considerable  enlargement 
of  the  visceral  cavities,  as  in  the  case  of  the  stomach  and  urinary  blad- 
der. In  contraction  of  organs  lined  with  mucous  membrane  this  be- 
comes rugose,  or  thrown  into  folds,  which  are  effaced  on  distention. 
These  folds,  however,  should  not  be  confounded  with  others  of  a  perma- 
nent character  existing  in  some  of  the  mucous  membranes,  as  for  instance, 
the  val'vulae  conniven'tes  of  the  small  intestine. 

The  mucous  membranes  are  less  transparent  in  general  than  the  serous 

1  Textus  cellularis  submucosus ;  tunica  cellularis ;  fibrous  coat ;  cellular  coat. 


THE   GLANDULAR  SYSTEM.  267 

membranes ;  are  more  vascular,  and  are  also  well  supplied  with  lym- 
phatics and  nerves.  They  vary  from  a  white,  grayish  white  and  pale 
pink,  to  dark  red,  the  shade  or  depth  of  redness  depending  mainly  on 
the  amount  of  blood  supplied.  Excitation  heightens  their  color,  and 
contact  with  the  air  favors  their  permanent  redness. 

Nearly  all  mucous  membranes  are  abundantly  supplied  with  minute 
glands  imbedded  in  their  fibrous  layer  or  the  contiguous  submucous 
tissue,  and  opening  on  their  free  surface. 

The  epithelium  of  mucous  membranes  presents  most  of  the  varieties 
of  cells  which  have  been  described.  Those  provided  with  a  columnar 
epithelium  are  usually  softer  and  more  moist  than  the  others.  The  base- 
ment membrane  and  fibrous  layers  of  structure  are  sufficiently  evident  in 
all  mucous  membranes. 

Mucus,  the  material  elaborated  by  the  mucous  membranes,  and  appa- 
rently by  many  of  their  glands,  is  a  clear,  colorless,  transparent,  viscid 
liquid,  frequently  rendered  more  or  less  turbid  by  cast-off  epithelial  cells, 
and  isolated  nuclear  bodies,  commonly  called  mucous  corpuscles.  It  is 
composed  of  water,  the  peculiar  organic  principle  mucosin,  and  alkaline 
salts. 

THE  GLANDULAR  SYSTEM. 

The  name  of  Gland  has  been  indiscriminately  applied  to  almost  every 
rounded,  massive  organ,  if  it  was  only  supposed  to  elaborate  certain 
liquid  materials  from  the  blood.  Thus  the  liver,  which  produces  the 
bile,  the  thyroid  body  whose  office  is  unknown,  the  rounded  masses  situ- 
ated in  the  course  of  the  lymphatics,  and  the  pituitary  body,  a  portion 
of  the  brain,  have  all  been  and  yet  continue  to  be  called  glands.  In 
this  confusion  of  parts  with  one  general  name,  it  is  our  object  at  present 
only  to  describe  those  which  are  commonly  distinguished  as  the  true 
glands.  These  may  be  defined  to  be  organs  which  elaborate  from  the 
blood  liquid  matters  poured  forth  by  one  or  more  ducts  or  orifices  open- 
ing on  the  surface  of  the  mucous  membranes  or  skin.  The  material 
elaborated  by  a  gland  is  called  a  secretion,  and  the  same  name  is  given 
to  the  act  of  elaboration.  If  the  secretion  is  to  be  rejected  from  the 
body  as  useless,  it  is  also  called  an  excretion.  The  term  secretion  is 
likewise  applied  to  mucus  and  serum,  and  to  the  elaboration  of  these  by 
their  appropriate  membranes. 

In  general,  the  glands  may  be  described  as  consisting  of  a  tube  or 
series  of  tubes  of  basement  membrane  lined  with  nucleated  cells,  and  in- 
vested externally  with  a  fibrous  layer  in  which  are  distributed  the  blood- 
vessels from  which  the  glands  elaborate  their  secretions.  The  difference 


268 


THE   GLANDULAR   SYSTEM. 


in  the  complexity  and  extent  of  glands  depends  mainly  on  the  difference 
in  number,  length,  and  arrangement  of  the  tubes. 


FIG.  188. 


FIG.  189. 


SIMPLE  GLAND  DILATED  INTO  A  POUCH.   References 
as  in  the  preceding  figure. 


DIAGRAM  OF  TWO  SIMPLE  TUBULAR  GLANDS.  The 
dotted  line  1  indicates  the  glandular  epithelium 
or  secreting  cells;  the  thicker  continuous  line  2, 
is  the  basement  membrane,  and  the  shaded  portion 
of  the  figure  3  represents  the  fibrous  tissue  in 
which  the  blood-vessels  are  distributed  which  sup- 
ply the  glands. 


The  simplest  form  of  a  gland 
consists  of  a  short,  straight  tube, 
closed  at  one  end,  and  opening  at 
the  other  upon  the  surface  of  a 
mucous  membrane,  as  instanced  in 
the  tubular  glands  of  the  small  intestines.  The  complexity  is  slightly 
increased  if  the  tube  is  dilated  into  a  purse-like  pouch,  as  in  the  simple 
sebaceous  glands  of  the  skin. 

If  the  simple  tube  or  pouch  is  divided  at  bottom  into  two  or  more 
similar  parts,  the  complexity  is  increased  according  to  the  number  of 
the  latter,  as  seen  in  tlie  gastric  glands,  and  compound  sebaceous  glands 
of  the  skin. 

The  glandular  tube  may  be  rendered  complex  by  becoming  more  or 
less  elongated  and  convoluted,  as  in  the  case  of  the  sweat  glands.  If 


FIG.  190. 


FIG.  191. 


FIG.  192. 


Fig.  190.  GLANDS  RENDERED  SLIGHTLY  COMPLEX  BY  DIVISION  AT  BOTTOM.    References  as  in  figure  188. 
Fig.  191.  INCREASE  OF  COMPLEXITY  OF  GLANDS  by  the  addition  of  similar  parts.    References  as  before. 
Fig.  192.  A  TUBULAR  GLAND  rendered  complex  by  becoming  elongated  and  convoluted.   Same  references. 

the  tube  divide  and  subdivide,  and  the  ultimate  branches  become  elon- 
gated and  convoluted,  the  gland  is  rendered  complex  according  to  the 
extent  of  branching  and  convolution,  as  exemplified  by  the  kidneys  and 
testicles. 

If  the  glandular  tube  divide  and  subdivide,  and  the  terminal  branches 


THE   GLANDULAR   SYSTEM. 


269 


dilate  into  vesicles,  a  complex  arrangement  is  produced  resembling  in 
appearance  a  bunch  of  grapes,  as  represented  in  the  construction  of  the 
salivary  glands.  If,  on  the  other  hand,  the  branching  tubes  form  a  net- 
work, a  complex  arrangement  results  such  as  is  seen  in  the  construction 
of  the  liver. 

FIG,  193.  FIG.  194.  FIG.  195. 


Fig.  193.  GLAND  OF  COMPLEX  FORM;  the  tubes  branching  and  the  terminal  ones  convoluted  and  dilated 
at  the  extremities.  1,  main  tube  or  duct ;  2,  branches;  3,  convoluted  portions  dilated  at  the  extremities. 

Fig.  194.  GLAND  OF  COMPLEX  FORM,  whose  arrangement  resembles  that  of  a  bunch  of  grapes.  1,  duct; 
2,  branches  ending  in  vesicles;  3,  branch  of  another  lobule. 

Fig.  195.  GLAND  OF  COMPLEX  CHARACTER  in  which  the  tubes  anastomose,  and  thus  form  a  net-work 
1,  duct;  2,  net-work  of  tubes. 

The  glands  may  be  classified  according  to  their  structural  arrangement, 
though  it  should  be  fairly  understood  that  the  different  forms  are  not 
separated  by  trenchant  characters,  but  pass  by  gradations  into  one 
another.  The  principal  forms  are  as  follows:  the  tubular,  racemose, 
convoluted,  and  reticular  glands. 

The  Tubular  glands  consist  of  simple,  straight  or  slightly  tortuous 
tubes  closed  at  one  end,  and  opening  at  the  other  on  the  surface  of  a 
mucous  membrane.  They  are  usually  short,  of  uniform  diameter  through- 
out, or  slightly  dilated  toward  the  closed  extremity ;  or  in  the  latter  po- 
sition they  may  divide  into  several  tubular  offsets  or  prolongations. 
They  are  imbedded  in  the  fibrous  layer  of  mucous  membranes,  and  in 
most  instances  are  provided  with  a  columnar  epithelium,  besides  the 
basement  membrane  and  fibrous  coat.  Such  are  the  tubular  glands  of 
the  large  and  small  intestine,  the  gastric  glands,  and  the  tubular  glands 
of  the  nose  and  uterus. 

The  Follic'ular  glands,  intermediate  to  the  former  and  the  succeeding 
variety,  and  passing  insensibly  from  one  into  the  other,  are  composed  of 
one  or  more  purse-like  pouches  lined  with  a  spheroidal  epithelium. 
When  the  pouches  are  numerous,  they  are  usually  collected  into  small 
groups  or  lobules  opening  into  a  common  canal  or  duct,  which  conveys 


270  THE   GLANDULAR  SYSTEM. 

the  secretion  to  the  surface  of  the  skin  or  mucous  membrane.  To  this 
variety  belong  the  sebaceous  glands  of  the  skin,  the  follicular  glands  of 
the  root  of  the  tongue,  soft  palate  and  pharynx,  and  the  tonsils. 

The  Rac'emose  glands  are  named  from  their  structure  resembling  in 
arrangement  the  appearance  of  a  raceme  or  cluster  of  grapes.  In  the 
construction  of  such  glands,  a  tube  divides  and  subdivides,  and  the 
smallest  branches  communicate  with  vesicular  dilatations  lined  with 
spheroidal  secreting  cells,  rendered  polyhedral  from  mutual  pressure. 
Groups  of  vesicles  and  their  associating  tubes,  which  may  be  compared 
with  the  small  clusters  of  a  bunch  of  grapes,  are  named  lobules,  In  the 
construction  of  a  large  racemose  gland,  the  latter  are  associated  in  still 
larger  portions,  a  number  of  which  together  may  form  the  largest  divi- 
sions or  lobes  of  the  gland. 

The  simplest  racemose  glands  present  a  striking  resemblance  to  a 
bunch   of    grapes,   but    the    more   compound 
FIG.  196.  glands,  or  those   consisting  of  a  number   of 

lobules  and  lobes,  are  modified  in  form  from 
mutual  pressure.  The  commencing  vesicles 
are  polyhedral,  the  lobules  and  lobes  are 
pyramidal,  and  the  whole  are  associated,  by  in- 
tervening connective  tissue,  into  a  more  or  less 
solid  mass.  The  tubes  or  ducts,  which  collect 
the  secretion  from  the  commencing  vesicles, 

th« 


A  RACEMOSE  GLAND.     1,  duct;   2, 

lobules  composed  of  the  terminal    a  principal  duct,  or  sometimes  several,  issuing 


n       °Penng  On  S0me 

membrane. 

The  duct  or  ducts  of  the  racemose  glands  have  fibrous  walls  lined  with 
mucous  membrane,  usually  provided  with  a  columnar  epithelium.  A  few 
of  the  principal  ducts  in  addition  are  furnished  with  unstriated  muscular 
fibres. 

To  the  racemose  glands  belong  the  pancreas,  the  salivary  glands,  the 
lachrymal  gland,  the  labial,  buccal,  palatine,  lingual,  pharyngeal,  oeso- 
phageal,  and  duodenal  glands,  the  tracheal  and  bronchial  glands,  the 
vaginal,  prostatic,  and  urethra!  glands. 

The  Convoluted  glands  are  composed  of  simple  or  branching  tubes, 
which,  at  their  commencement,  are  enrolled  upon  themselves  or  convoluted 
into  masses.  The  simplest  forms  are  the  sweat  glands  ;  the  compound 
forms  are  the  kidneys  and  testicles. 

The  only  gland  exhibiting  a  reticular  arrangement  in  its  intimate 
structure  is  the  liver.  This  organ  is  divided  on  the  surface  into  several 
lobes,  and  these  are  composed  of  an  aggregation  of  small  and  closely 


UNSTRIATED   MUSCULAR   TISSUE.  271 

adherent  polyhedral  lobules  or  acini.  Independently  of  the  blood-ves- 
sels, the  acini  consist  of  a  net-work  of  polyhedral  glandular  cells ;  but 
whether  they  occupy  the  interior  of  tubes  of  basement  membrane,  as  in 
other  glands,  is  still  a  point  which  remains  undetermined  to  the  satisfac- 
tion of  most  anatomists.  Ducts  proceeding  from  the  acini,  as  in  other 
secretory  organs,  converge  to  trunks  composed  of  fibrous  walls,  with  a 
lining  of  mucous  membrane. 

The  glands  are  most  richly  furnished  with  blood-vessels,  which  form 
capillary  nets  around  or  among  the  glandular  tubes.  They  likewise  pos- 
sess numerous  lymphatics,  and  are  also  supplied  with  nerves. 

UNSTRIATED  MUSCULAR  TISSUE. 

Most  of  the  hollow  viscera,  including  the  vascular  system  and  a  few 
other  parts,  are  provided  with  muscular  layers  of  a  different  structure 

FIG.  197. 


UNSTRIATED  MUSCULAR  FIBRE.     1,  from  the  small  intestine;  2,  from  the  middle  coat  of  an  artery;  3, 
from  a  vein. 

from  that  already  described,  and  named,  in  contradistinction,  the  unstri- 
ated  muscular  tissue.1  The  unstriated  muscular  fibres  of  the  latter 
consist  of  fusiform,  rounded,  or  slightly  prismoid  columns  or  bands, 
varying  considerably  in  the  proportions  of  length  and  breadth  in  the 
different  organs.  They  range  from  tne  fa  to  the  T\j  of  a  line  in  length, 
are  faintly  yellowish  or  colorless,  homogeneous,  or  indistinctly  granu- 
lar, and  present  no  trace  of  transverse  striation.  They  consist  of  single, 
elongated  cells,  pointed  at  the  extremities,  and  always  provided  with  a 
central,  oblong  oval  nucleus. 

The  unstriated  muscular  fibres  are  usually  associated  into  fasciculi, 
and  these  are  arranged  into  layers  or  membranes,  having  a  yellowish- 
brown  appearance.  These  muscular  layers  are  abundantly  supplied  with 
blood-vessels  and  nerves,  which  have  the  same  general  arrangement  as 
in  the  striated  muscles.  The  unstriated  muscular  tissue  is  excited  to 
contraction  usually  through  reflex  impressions,  but  may  also  be  excited 
by  the  direct  impression  of  most  of  the  stimuli  operating  on  the  striated 
muscles,  except  the  will. 

1  Unstriped,  or  non-striated  muscular  tissue  or  fibres ;  smooth  muscles,  or  mus- 
cular fibres  ;  organic  muscular  tissue  or  fibres ;  muscular  tissue  of  organic  life. 


272  UNSTRIATED  MUSCULAR   TISSUE. 

Unstriated  muscular  tissue  constitutes  the  muscular  coat  of  the 
stomach,  small  and  large  intestine,  and  the  muscular  fibres  noticed  in 
the  mucous  membrane  of  these  organs.  A  thin  layer  is  also  found  on 
the  gall-bladder  and  in  certain  glandular  ducts.  It  forms  the  muscular 
coat  of  the  urinary  bladder,  the  walls  of  the  uterus,  and  a  layer  to  the  Fal- 
lopian tubes,  vagina,  and  urethra.  In  association  with  elastic  tissue,  it 
composes  the  middle  coat  of  the  blood-vessels  and  lymphatics,  and  fur- 
ther constitutes  the  muscular  structure  of  the  trachea,  bronchi  and  their 
ramifications.  Finally,  it  forms  the  dartos  layer  of  the  scrotum,  and  is 
found  in  other  parts  of  the  skin,  especially  in  the  walls  of  the  odoriferous 
glands  of  the  axillae. 


CHAPTER  YL 

THE  ALIMENTARY  APPARATUS. 

THE  Alimentary  apparatus  consists  of  the  aliment'ary  canal,1  to- 
gether with  a  number  of  accessory  organs.  The  former  comprises  two 
divisions,  of  which  one  is  constituted  by  the  mouth  and  the  organs  of 
deglutition,  consisting  of  the  pharynx  and  resophagus;  the  other,  by 
the  digestive  organs,2  contained  within  the  abdomen,  and  composed  of 
the  stomach  and  the  small  and  large  intestines.  The  accessory  organs 
are  those  of  mastica'tion,  consisting  of  the  teeth,  jaws,  and  appropriate 
muscles,  and  the  tongue,  salivary  glands,  pancreas,  and  the  liver. 

THE  MOUTH. 

The  Mouth3  is  the  space  included  between  the  lips  in  front,  the 
pharynx  behind,  and  the  cheeks  at  the  sides.  Above,  it  is  bounded  by 
the  roof  or  palate,  inclosed  by  the  upper  teeth  and  alveolar  arch ;  below, 
is  its  floor,  upon  which  rests  the  tongue,  included  within  the  lower  teeth 
and  alveolar  arch.  The  closed  jaws  and  teeth  divide  the  mouth  into  two 
portions :  the  narrow  interval4  between  the  lips,  cheeks,  and  the  jaws, 
and  the  larger  cavity  within  the  latter,  containing  the  tongue. 

The  cavity  of  the  mouth,5  except  on  the  teeth,  is  everywhere  invested 
with  a  highly  vascular  mucous  membrane,  provided  with  a  squamous  epi- 
thelium. It  is  also  furnished  with  conical  papilla?,  for  the  most  part 
minute  and  concealed  beneath  the  epithelium,  except  at  the  margins  of 
the  gums,  and  more  especially  on  the  upper  surface  of  the  tongue,  where 
they  become  conspicuous  as  the  chief  organs  of  taste. 

The  Gums6  consist  of  reflections  of  the  oral  mucous  membrane  upon 
the  alveolar  arches.  They  closely  adhere  to  the  periosteum  beneath,  and 
form  circular  doublings  or  collars  around  the  necks  of  the  teeth,  with 
which  they  are  intimately  connected. 

1  Canalis,  tubus,  or  ductus  alimenta-          3  Os ;  stoma;  cavum  oris. 
rius,  ciliarius,   digestivus,   or  intestine-          *  Vestibulum  oris. 

rum ;  digestive  canal ;  intestinal  canal ;          5  Cavum,  or  spatium  oris. 
primoe  vise.  6  Gingivse  ;  carnicula ;  ula. 

2  Organon  digestionis. 

18  (273) 


274 


THE  ALIMENTARY  APPARATUS. 


The  Lips1  are  separated  by  the  oral  fissure,2  the  extremities  of  which 
constitute  the  oral  angles  or  commissures.3  Besides  the  exterior  skin, 
with  its  subjacent  connective  tissue  and  fat,  the  lips  are  composed  of  vari- 
ous muscles  converging  to  and  surrounding  the  oral  fissure,  together  with 

FIG.  198. 


VERTICAL  SECTION  OF  THE  FACE  AND  NECK,  THROUGH  THE  MEDIAN  LINE  ANTERO-POSTERIORLY,  EXPOSING  TO 
VIEW  THE  NOSE,  MOUTH,  PHARYNX,  AND  LARYNX.  1,  oval  cartilage  of  the  left  nostril ;  2, triangular  cartilage; 
3,  line  of  separation  between  the  two;  4,  prolongation  of  the  oval  cartilage  along  the  column  of  the  nose; 
5,  superior  meatus  of  the  nose;  6,  middle  meatus;  7,  inferior  meatus;  8,  sphenoidal  sinus;  9,  posterior 
part  of  the  left  nasal  cavity,  communicating  with  the  pharynx;  10,  orifice  of  the  Eustachian  tube;  11, 
upper  extremity  of  the  pharynx ;  12,  soft  palate,  ending  below  in  the  uvula ;  13,  interval  of  the  mouth 
between  the  lips  and  jaws;  14,  roof  of  the  mouth,  or  hard  palate;  15,  communication  of  the  cavity  of  the 
mouth  with  the  interval  between  the  jaws  and  cheek;  16,  tongue;  17,  fibrous  partition  in  the  median  line 
of  the  latter;  18,  genio-glossal  muscle;  19,  genio-hyoid  muscle;  20,  mylo-hyoid  muscle;  21,  anterior  half 
arch  of  the  palate;  22,  posterior  half  arch  of  the  palate;  23,  tonsil;  24,  25,  floor  of  the  fauces;  26,  27, 
pharynx;  28  cavity  of  the  larynx;  29,  ventricle  of  the1  larynx;  30,  epiglottis;  31,  hyoid  bone;  32,  33, 
thyroid  cartilage;  34,  tbyro-hyoid  membrane;  35,  36,  cricoid  cartilage;  37,  vocal  membrane. 


1  Sing.:   labium;    pi.:  labia;  labrum, 
cheilos;  upper  and  under  lip;  anochei- 
los  and  catacheilos. 

2  Rima,  apertura,  orificium,  or  hiatus 
oris;  os;  peristonrium. 


3  Angles,  or  commissures  of  the  mouth 
or  of  the  lips;  commissura  labiorium ; 
prostomin. 


THE  ALIMENTARY  APPARATUS.  275 

the  lining  mucous  membrane  and  a  number  of  glands.  The  orbicular 
muscle  borders  the  oral  fissure  or  orifice  of  the  mouth,  and  is  covered 
by  thin  skin,  gradually  passing  into  mucous  membrane.  Between  the 
lips  and  jaws,  in  the  median  line,  the  mucous  membrane  forms  doublings, 
named  the  superior  and  the  inferior  labial  free 'num.1 

The  Cheeks2  have  a  composition  similar  to  the  lips,  and  their  princi- 
pal muscle  is  the  buccinator.  At  their  back  part  they  include  the  ramus 
of  the  lower  jaw  and  its  muscles,  and  also,  usually  between  these  and  the 
buccinator  muscle,  a  mass  of  soft  adipose  tissue. 

Beneath  the  mucous  membrane  of  the  lips  and  cheeks  there  are  numer- 
ous small,  rounded,  pinkish  racemose  glands,  opening  by  their  ducts  into 
the  mouth,  and  named  from  their  position  the  labial3  and  buccal  glands.4 
Though  they  are  supposed  to  secrete  mucus,  their  office  has  not  been 
satisfactorily  determined. 

The  Palate,  or  roof  of  the  mouth,5  comprises  two  parts,  called  the  hard 
and  soft  palate. 

The  Hard  palate6  is  deeply  vaulted,  and  is  lined  with  a  smooth  mu- 
cous membrane,  except  at  its  fore  part,  where  it  is  roughened  by  trans- 
verse ridges.  It  is  divided  by  a  faintly-marked  median  line,7  ending  in  a 
small  prominence,  corresponding  with  the  position  of  the  incisive  fora- 
men. Its  osseous  basis  is  formed  by  the  palate  plates  of  the  superior 
maxillary  and  palate  bones,  to  which  the  mucous  membrane  adheres  by  a 
dense  layer  of  fibrous  tissue,  containing  numerous  small  racemose  glands, 
named  from  their  position  the  palatine  glands.8 

The  Soft  palate9  is  composed  of  a  doubling  of  mucous  membrane,  in- 
closing a  fibro-muscular  layer,  together  with  many  small  racemose  and 
follicular  glands.  It  projects  as  a  freely  movable  partition  obliquely 
downward  and  backward  from  the  hard  palate,  between  the  mouth  and 
posterior  nasal  orifices. 

The  U'vula10  is  the  small,  tongue-like  appendage  projecting  from  the 

1  Fraenum,  or  frsenulum  labii  superi-  velum  palatinum,  pendulum,  or  staphyli- 
oris  et  inferioris.  num ;  velum  palati,  or  pendulum  palati ; 

2  Genae  ;  malae.  pendulum,  or  claustrum  palati ;  pendu- 

3  Glandulse  labiales.  lous  veil  of  the  palate. 

*  Glandulae  buccales.  ™Uva;    uvigena;    uvigera;   staphyle; 

5  Palatum ;  fossa  palatina ;  uraniscos ;  columella,  or  columna  oris ;  sublingua : 
hyperoa.  tintinnabulum ;  gargarlon ;  gurgulis ;  in- 

6  Palatum  durum,  or  stabile.  terseptum ;  processus,  or  cartilage  uvi- 

7  Raphe.  fer;  pinnaculum  fornicis  gutturalis;  hi- 

8  Glandulse  palatinse.  mas;  plestrum;  pap  of  the  throat;  the 

9  Palatum  molle,  mobile,  or  pendulum;  palate. 


276  THE  ALIMENTARY  APPARATUS. 

middle  of  the  soft  palate,  and  consists  of  a  pair  of  muscles  inclosed  in  a 
pouch  of  mucous  membrane. 

The  Half  arches  of  the  Palate  are  two  crescentic  folds  of  mucous 
membrane,  inclosing  muscular  fasciculi,  and  diverging  from  the  base  of 
the  uvula,  on  each  side  of  the  palate,  outward  and  downward,  one  to  the 
side  of  the  tongue,  the  other  to  the  side  of  the  pharynx.  The  anterior 
pair  inclose  the  palato-glossal  muscles,  and  together  constitute  the 
anterior  palatine  arch  j1  the  posterior  pair  inclose  the  palato-pharyngeal 
muscles,  and  constitute  together  the  posterior  palatine  arch,2 

The  Fau/ces3  are  the  straits  or  passage  leading  from  the  mouth  to  the 
pharynx,  and  correspond  with  the  space  included  between  the  palatine 
arches. 

The  Ton'sils4  are  two  glandular  organs,  about  the  size  and  shape  of 
an  almond  kernel,  situated  one  on  each  side  of  the  fauces,  inclosed  in 
the  triangular  recess  between  the  half  arches  of  the  palate.  They  are 
in  contact  externally  with  the  superior  constrictor  muscles  of  the  pha- 
rynx, and  move  with  the  contraction  of  these  muscles.  Their  surface 
toward  the  fauces  presents  a  coarsely  reticular  appearance,  due  to  a 
number  of  large  orifices  communicating  with  pouches,  in  the  bottom  of 
which  the  orifices  of  smaller  pouches  are  visible.  They  are  large  com- 
pound follicular  glands  of  peculiar  constitution. 

Simple  follic'ular  glands  of  the  same  character  as  the  tonsils  occupy 
the  floor  of  the  fauces  or  the  root  of  the  tongue,  the  palate,  and  the  pha- 
rynx. These  are  distinguished  as  rounded  prominences  of  the  mucous 
membrane,  with  an  orifice  communicating  with  the  mouth  or  pharynx. 
They  consist  of  a  purse  or  bottle-like  inflection  of  the  mucous  mem- 
brane, and  contain  in  their  thick  walls  of  submucous  tissue  a  number  of 
spheroidal  capsules  or  vesicles  resembling  in  composition  the  solitary 
glands  of  the  intestines.  The  tonsils  differ  from  the  simple  follicular 
glands  only  in  their  compound  form,  or,  in  other  words,  they  consist  of 
an  aggregation  of  such  bodies  as  constitute  the  glands  just  named. 

The  recesses  of  the  tonsils  and  simple  follicular  glands  ordinarily 
appear  to  elaborate  mucus,  which  lubricates  the  fauces  in  the  passage  of 
food.  Under  the  influence  of  cold,  these  glandular  organs  are  very  sus- 

1  Arcus  palatinus  anticus;    a.  palato-  4  Sing.:    tonsilla ;  amygdala;  paristh- 
glossus.  mia ;  tola ;  spongos ;  antias  ;  amphibran- 

2  Arcus  palatinus  posticus ;  a.  palato-  chium  ;    glandula  colli ;    almond  of  the 
pharyngeus.  throat  or  of  the  ear. 

3  Isthmus  of  the  fauces ;   i.  faucium ; 
claustrum  gutturis. 


THE  ALIMENTARY  APPARATUS. 


277 


ceptible  to  inflammation 
condition  their  recesses 
tallow-like  matter,  which 
of  small,  rounded  balls. 
These,  when  crushed,  ex- 
hale a  heavy,  disagreeable 
odor,  indicating  a  source 
of  foul  breath,  independ- 
ent of  the  more  ordinary 
one.  The  material  exam- 
ined beneath  the  micro- 
scope exhibits  nothing  but 
squamous  epithelial  cells, 
together  with  some  oil 
globules,  and  minute,  par- 
asitic, filamentous  plants. 


and  chronic  enlargement.     In  the  unhealthy 

frequently  become    filled  with   a  dirty-white 

is  from  time  to  time  expectorated  in  the  form 

FIG.  199. 


SECTION  OF  A  FOLLICULAR  GLAND  FROM  THE  ROOT  OF  THE  TONGUE. 
a,  epithelium ;  6,  papillfe  imbedded  in  the  latter ;  c,  outer  part 
of  the  thick  wall  of  the  gland  composed  of  connective  tissue; 
d,  mouth  of  the  gland ;  e,  its  cavity ;  /,  epithelium  lining  the  lat- 
ter; g,  vesicular  bodies  resembling  the  solitary  glands  of  the 
intestines.  Highly  magnified. 


MUSCLES  OF  THE  PALATE  AND  FAUCES. 

The  Eleva'tor  of  the  Palate1  is  a  thin,  flat  muscle,  which  arises  from 
the  end  of  the  petrous  portion  of  the  temporal  bone  and  the  contiguous 

FIG  200. 


POSTERIOR  VIEW  OF  THE  MUSCLES  OF  THE  PALATE  AND  FAUCES.  1,  elevator  of  the  palate,  on  the  left  side 
its  origin  only  remaining;  2,  tensor  of  the  palate,  winding  around  the  hook  of  the  internal  pterygoid 
process  and  ending  in  the  soft  palate;  3,  uvular  muscles;  4,  Eustachian  tube;  5,  origin  of  the  palato- 
pharyngeal  and  palato-glossal  muscles ;  6,  part  of  the  origin  of  the  superior  constrictor  of  the  pharynx ; 
7,  external  pterygoid  muscle. 

1  M.  levator  palati  mollis;  m.  salpingo-staphylinus ;  m.  s.-s.  interims ;  m.  petro- 
salpingo-staphylinus ;  m.  pterygo-staphylinus  externus;  m.  spheno-staphylinus;  m. 
spheno-palatinus ;  m.  peristaphylinus  internus  superior ;  m.  petro-staphylinus. 


278  THE  ALIMENTARY  APPARATUS. 

portion  of  the  Eustachian  tube,  and  descends  at  the  side  of  the  posterior 
nasal  orifice  to  expand  in  the  structure  of  the  soft  palate. 

The  Ten/sor  of  the  Palate1  is  a  narrow  muscle  arising  from  the  fossa, 
at  the  root  of  the  internal  pterygoid  process,  and  from  the  contiguous 
portion  of  the  Eustachian  tube.  Descending  at  the  inner  side  of  the 
pterygoid  fossa,  it  terminates  in  a  tendon  which  winds  around  the  hook 
of  the  internal  pterygoid  process,  and  expands  into  a  thin  aponeurosis 
within  the  soft  palate. 

The  TTvular  muscle2  is  a  fleshy  fasciculus  arising  from  the  palate 
spine  of  the  palate  bone,  and  descending  in  company  with  its  fellow 
into  the  uvula. 

The  Pal'ato-glos'sal  muscle3  is  situated  within  the  anterior  half  arch 
of  the  palate,  extending  from  the  side  of  the  soft  palate  to  the  tongue. 

The  Floor  of  the  mouth,  included  within  the  lower  jaw,  is  formed  by 
the  skin,  the  mylo-  and  genio-hyoid  muscles,  and  the  mucous  membrane 
reflected  from  the  gum  to  the  under  part  of  the  tongue. 

THE  SALIYAEY  GLANDS. 

Opening  into  the  cavity  of  the  mouth  there  are  three  pairs  of  salivary 
glands,  named  the  parotid,  submaxillary  and  sublingual  glands. 

The  Parot'id  gland,*  the  largest  of  the  salivary  glands,  occupies  a  po- 
sition in  front  of  the  external  ear,  reaching  a  short  distance  over  the 
masseter  muscle.  It  extends  as  high  as  the  zygoma,  as  far  down  as 
the  angle  of  the  lower  jaw,  and  dips  inwardly  between  the  ramus  of  the 
latter  and  the  mastoid  process  to  the  position  of  the  styloid  process  and 
muscles.  Passing  through  its  length,  we  find  the  external  carotid  artery 
and  accompanying  vein,  and,  diverging  through  it  in  an  opposite  direc- 
tion, the  facial  nerve. 

The  parotid  is  a  large  compound  racemose  gland,  consisting  of  numer- 
ous polyhedral  lobes,  closely  moulded  upon  the  surfaces  with  which  the 
gland  comes  into  contact.  The  lobes  are  subdivided  into  lobules,  the 


1  M.  tensor  palati  mollis ;  m.  circum-  2  Azygos   muscle   of    the   uvula ;     m. 

flexus  palati;   m.  salpingo-staphylinus ;  azygos   uvulae;    m.  palato-staphylinus; 

m.  petro-salpingo-staphylinus;  m.  ptery-  m.  staphylinus ;    m.  epistaphylinus;   m. 

go-staphylinus ;  m.  spheno-salpingo-  staphylinus  medius. 

staphylinus;    m.  peristaphylinus  exter-  3  M.    palato-glossus :    m.    constrictor 

nus  or  inferior ;  m  staphylinus  externus ;  isthmii  faucium;  m.  glosso-staphylinus; 

m.  palato-salpingeus ;  m.  spheno-pterygo-  m.  glosso-palatinus. 

palatinus ;  m.  tubse  novse.  *  Glandula  parotidea;  g.  adaures;  pa- 

rotis ;  animellae  ;  lacticinia. 


THE  ALIMENTARY  APPARATUS.  279 

whole  being  connected  together  by  dense  areolar  tissue,  continuous  ex- 
ternally with  that  enveloping  the  gland  and  adhering  to  the  contiguous 
parts. 

The  Parot/id  duct,1  about  the  diameter  of  a  crow-quill,  and  two  inches 
in  length,  passes  forward  from  the  gland  across  the  masseter  muscle,  a 
short  distance  below  the  zygoma,  and  opens  into  the  mouth  by  perforat- 
ing the  buccinator.  Its  orifice,  somewhat  contracted,  is  indicated  by  a 
small  prominence  opposite  the  position  of  the  second  upper  large  molar 
tooth. 

Usually  a  detached  portion  of  the  gland,  named  the  accessory  parotid,2 
rests  on  the  masseter  muscle,  and  communicates  by  its  duct  with  the  main 
one. 

The  Submax'illary  gland,3  about  a  third  the  size  of  the  preceding, 
and  separated  from  it  by  a  strong  process  of  the.  deep  cervical  fascia,  is 
situated  just  within  and  below  the  base  of  the  lower  jaw.  It  is  beneath 
the  mylo-hyoid  muscle  ;  is  included  below  in  the  curve  of  the  digastric 
muscle,  and  externally  is  covered  by  the  subcutaneous  cervical  muscle 
and  skin.  Its  structure  is  like  that  of  the  parotid  gland,  but  its  lobes 
are  coarser,  its  connective  tissue  much  less  in  quantity,  and  its  attach- 
ment to  the  contiguous  parts  comparatively  feeble. 

The  Submax'illary  duct,4  about  two  inches  in  length,  passes  backward, 
turns  over  the  posterior  edge  of  the  mylo-hyoid  muscle,  and  is  then  di- 
rected forward  between  this  and  the  hyo-glossal  muscle  to  the  side  of  the 
lingual  fraenum,  where  it  terminates  at  the  summit  of  a  small  promi- 
nence.5 An  accessory  portion  of  the  gland  follows  the  duct  a  short 
distance  and  communicates  with  it. 

The  Sublin'gual  gland,6  the  smallest  of  the  salivary  glands,  is  narrow 
oblong  in  shape,  and  rests  on  the  floor  of  the  mouth,  projecting  into  its 
cavity  as  a  conspicuous  ridge  beneath  the  side  of  the  tongue.  It  ex- 
tends from  the  position  of  the  lingual  fraenum  to  the  submaxillary  gland, 
and  is  in  contact  with  the  duct  of  the  latter. 

The  sublingual  gland  has  the  same  structure  as  the  other  salivary 
glands ;  but  its  lobules  are  less  closely  associated.  It  communicates 
with  the  cavity  of  the  mouth  by  about  half  a  dozen  small  ducts,7  which 

1  Duct  of  Steno;  ductus  Stenonianus:  4  Duct  of  Wharton;  ductus  Whartoni- 

d.  salivalis  superior.  anus ;  d.  salivalis  inferior. 

.     2  Glandula  socia  parotidis ;  accessory  5  Caruncula  sublingualis. 

gland  of  the  parotid:   g.  parotis  acces-  6  Glandula  sublingualis;   in  part,  the 

soria.  glands  of  Rivinus. 

3  Glandula  submaxillaris ;    g.  angula-  7  Ductus  Rivini ;  d.  Waltheriani. 
ris;  g.  maxillaris;  hypognathaden ;  hy- 
posialaden. 


280  THE  ALIMENTARY  APPARATUS. 

open  upon  the  ridge  indicating  its  position.  Frequently  several  of  the 
ducts  unite  into  a  single  one,1  terminating  near  to,  or  in  conjunction  with, 
the  submaxillary  duct. 

The  secretion  of  the  salivary  glands,  the  sali'va,2  is  a  colorless  liquid 
of  slightly  alkaline  reaction.  It  is  rendered  more  or  less  viscid  by  the 
mixture  of  mucus,  and  contains  a  few  epithelial  scales  and  so-called 
mucous  corpuscles  or  free  nuclei. 

The  parotid  gland  is  supplied  with  arteries  from  the  external  carotid, 
the  submaxillary  gland  from  the  facial,  and  the  sublingual  gland  from 
the  sublingual  artery.  The  veins  terminate  in  those  accompanying  the 
corresponding  arteries.  The  nerves  are  derived  from  the  contiguous 
vascular  plexuses  of  the  sympathetic,  in  conjunction  with  filaments  of 
the  trifacial  nerve. 

THE  TONGUE. 

The  Tongue3  is  a  muscular  organ  invested  with  mucous  membrane,4 
and  ordinarily,  when  at  rest,  occupies  a  position  within  the  arch  of  the 
lower  jaw.  From  its  freedom  of  movement  it  aids  in  the  process  of 
mastication  and  deglutition,  and  contributes  to  articulation  in  speech ; 
from  the  papillae  of  its  surface  it  constitutes  the  organ  of  taste. 

The  posterior  part  of  the  tongue  attached  to  the  hyoid  bone  is  named 
its  root  or  base,5  and  that  which  is  attached  along  the  middle  to  the  floor 
of  the  mouth  is  the  body.  The  tip,6  sides,7  and  upper  surface8  are  free, 
and  invested  with  mucous  membrane,  which,  from  beneath  the  tongue,  is 
reflected  to  the  lower  gum. 

Between  the  root  of  the  tongue  and  the  epiglottis,  the  mucous  mem- 
brane forms  three  folds,  named  the  glos'so-epiglot'tic  frae'na  ;9  and  be- 
neath the  tip  of  the  tongue  a  median  fold  passes  to  the  gum,  and  is 
called  the  lin'gual  frae'num.10 

The  mucous  membrane  of  the  under  part  of  the  tongue  is  thin  and 
translucent,  and  permits  the  blood-vessels,  especially  the  ranine  veins, 
and  a  number  of  small  racemose  glands,  distinctly  to  be  seen  through  it. 
Beneath  the  tip  it  forms  a  slightly  elevated  median  line  or  raphe'  which 
is  continuous  with  the  lingual  frsenum. 

1  Ductus  Bartholini.  6  Dental  extremity  ;  point. 

2  Sputum;     sputamentum;     ptyalon;  7  Margins, 
rfialon ;  spit ;  spittle.  8  Dorsum. 

3  Lingua ;  glossa ;  glotta.  9  Glosso-epiglottic  ligaments ;    frama, 

4  Periglottis :     membrana,    or    tunica  or  frsenula  epiglotidis ;  ligamenta  mem- 
vaginalis ;    involucrum  ;    cutis ;    epider-  branacea  ;  velamenta  linguae. 

mis ;  crusta  villosae.  10  Frgenum,    frcenulum,    or    vinculum 

5  Radix  ;  hyoid  extremity.  linguse  ;  glossodesmus ;  filetum. 


THE  ALIMENTARY  APPARATUS. 


281 


The  upper  surface  or  back  of  the  tongue1  is  marked  along  the  middle 
by  a  slight  furrow,2  which  corresponds  in  position  with  a  thin  fibrous  par- 
tition,3 dividing  the  organ  into  symmetrical  halves. 


FIG.  201. 


VIEW  OF  THE  UPPER  SURFACE  OF  THE  TONGUE.  1,  2,  V-like  row  of  the  circumvallate  papilla?;  3,  capitate 
papillae;  4,  5,  conical  papillae;  6,  0,  floor  of  the  fauces,  with  numerous  simple  follicular  glands;  7,  tonsils; 
8,  summit  of  the  epiglottis;  9,  the  middle  glosso-epiglottic  fraenum,  with  depressions  on  each  side  bounded 
externally  by  the  lateral  fraena. 

Upon  the  anterior  two-thirds  of  the  upper  surface  of  the  tongue,  the 
mucous  membrane  adheres  most  intimately  to  the  muscular  structure 
beneath,  and  is  especially  remarkable  from  its  being  densely  beset  with 

1  Dorsum.  2  Linea  mediana ;  raphe. 

3  Septum  linguae  ;  cartilage  linguae  ;  c.  mediana ;  lingual  nbro-cartilage. 


282  THE  ALIMENTARY  APPARATUS. 

small  processes,  named,  from  their  function,  the  papillae  of  taste.1  The 
principal  of  these  are  of  a  composite  character,  and  present  three  varie- 
ties, called  the  circumvallate,  capitate,  and  conical  papillae. 

The  Circumval'late  papil'lae,2  the  largest  of  the  varieties,  and  about 
a  dozen  in  number,  form  a  Y-like  row,  defining  the  papillary  layer  at  the 
posterior  third  of  the  tongue.  They  have  the  form  of  an  inverted  cone, 
surrounded  by  an  annular,  wall-like  elevation,  whence  their  name. 

The  Cap'itate  papillae,3  the  second  in  size,  and  more  numerous  than 
the  preceding,  are  conspicuous  as  small,  red  eminences,  scattered  over 
the  surface  of  the  tongue,  but  are  especially  numerous  at  and  near  the 
tip.  They  are  rounded  at  the  free  extremity,  and  narrower  at  the  basis 
of  attachment. 

The  Conical  papil'lae/  smaller  and  much  more  numerous  than  the 
others,  are  crowded  in  the  intervals  between  them,  but  are  arranged  in 
rows  diverging  from  the  median  line  of  the  tongue. 

All  the  papillae  of  taste,  as  described  above,  and  the  intervals  between 
them,  are  covered  with  numerous  minute,  simple  papil'lae5  of  a  conical 
form.  From  those  surmounting  the  conical  papillae,  the  squamous  epi- 
thelium rises  in  hair-like  appendages,  which  give  to  these  papillae  a 
pencil-  or  brush-like  arrangement,  admirably  adapted  to  the  imbibition 
of  liquids  to  be  tasted.  To  these  hair-like  processes  is  due  the  velvety 
character  of  the  surface  of  the  tongue ;  and  it  is  upon  them  also  that 
the  so-called  furred  condition  of  the  latter  depends. 

The  papillae  of  taste  are  processes  of  the  mucous  membrane  of  the 

tongue,  richly  supplied 

FIG.  202.  with  blood-vessels.  The 

modes  of  termination  of 
the  nerves  within  these 
organs  has  not  yet  been 
^&ss55z-&*&*&&e&*.  satisfactorily  determined, 

DIAGRAM  OP  THE  PAPILLA  OF  THE  TONGUE,  moderately  magnified.  ^Ut  the  prevalent  Opinion 
1,  capitate  papillae ;  2,  conical  papillae ;  3,  epithelium ;  4,  the  same  jg  that  they  end  HI  loops 
structure  forming  bunches  of  hair-like  processes;  5,  connective  .,  .  ,  .„ 

tigsue  in    the    simple    papillae. 

The  capillary  blood-ves- 
sels distinctly  appear  within  the  latter  in  the  form  of  loops  communicat- 
ing with  the  vascular  trunks  at  their  base. 

1  Papillae  gustatoriae.  3  P.  capitatae;  p.  fungiformes;   p.  cla- 

2  P.  circumvallatae;  p.  vallatae;  p. max-  vatse  ;  p.  mediae;   p.  semilenticulares. 
imae;   p.  truncatae ;    p.  calyciformes ;  p.  4  P    conicae  ;  p    minimae ;  p    pyrami- 
mucosae  :  p.  lenticulares.  dales  :  p.  villosae  ;  p.  conicae  et  filiformes. 

5  P.  filiformes ;  filla ;  villi  linguae. 


THE  ALIMENTARY  APPARATUS. 


283 


Back  of  the  position  of  the  circumvallate  papillae,  corresponding  with 
the  floor  of  the  fauces,  the  tongue  is  provided  with  numerous  glands, 
named  the  lingual  glands.1  These  are  of  two  kinds :  racemose  glands, 
probably  secreting  mucus ;  and  follicular  glands,  which  have  the  peculiar 


FIG.  203. 


PAPILLA  OF  THE  TONGUE,  highly  magnified.  1,  conical  papillae;  2,  capitate  papilla;  3,  simple  papillae, 
occupying  the  intervals  of  the  compound  papillae ;  4,  epithelium  ascending  from  the  conical  papillae  in 
hair-like  processes;  5,  isolated  epithelial  scales  from  the  latter. 

constitution  of  the  tonsils,  the  follicular  glands  of  the  palate  and  pha- 
rynx. A  group  of  the  lingual  glands  usually  opens  into  a  small  pouch2 
just  behind  the  middle  circumvallate  papilla.  As  previously  indicated, 
a  number  of  racemose  glands  also  exist  beneath  the  tongue ;  and  others 
likewise  are  found  imbedded  in  the  muscular  structure  of  its  sides. 


MUSCLES  OF  THE  TONGUE. 

The  muscles  of  the  tongue  form  the  great  bulk  of  the  organ.  For 
the  most  part  they  are  inserted  into  the  fibrous  layer  of  its  investing 
mucous  membrane,  and,  as  they  approach  the  latter,  their  fasciculi  form 
an  intricate  intertexture,  associated  with  many  bundles  of  transverse,3 
longitudinal,4  and  vertical  muscular  fibres.5  Mingled  with  these  fibres 
there  is  a  quantity  of  adipose  tissue,  which  in  some  measure  appears  to 
take  the  ordinary  position  of  connective  tissue. 


1  Glanduloe  linguales. 

2  Foramen  coecum  :  f.  Morgagni. 

3  Musculus  transversus  linguae  ;  mus- 
culi  transversales. 


4  M.  longitudinalis  superior;  m.  chon- 
droglossus;  m.  superncialis  linguae  ;  mus- 
culi  longitudinales. 

5  Musculi  verticales. 


284 


THE  ALIMENTARY  APPARATUS. 


FIG.  204. 


The  Hyo-glos'sal  muscle1  is  a  quadrilateral  plane  of  fibres  arising 

from  the  great  horn  and 
body  of  the  hyoid  bone, 

^  j_—  ,/  and  ascending  to  expand 

^rjgjjpp  .^  ^e  g.^e  ^  ^e  tongue, 

between  the  stylo-glossal 
and  lingual  muscles. 


The  Geni'o-gios'sal 
muscle2  is  a  thick,  fan- 
shaped  layer  of  fibres, 
arising  tendinously  from 
the  posterior  mental  tu- 
bercle, and  radiating  back- 
ward and  upward  to  be 
inserted  into  the  tongue 
from  its  tip  to  its  attach- 
ment to  the  hyoid  bone. 
It  is  separated  from  the 
muscle  of  the  opposite 
side  by  a  thin  partition  of 
fibrous  tissue. 


SIDE    VIEW   OF    THE   MUSCLES    OF    THE    TONGUE.      1,  2,  StylO-glOSSal 

muscle;  3,  lingual  muscle;  4,  upper  part  of  the  tongue;  5,6,  hyo- 
glossal  muscle;  7,  genio-glossal  muscle;  8,  stylo-pharyngeal 
muscle ;  9,  genio-hyoid  muscle ;  10, 11,  median  line  of  the  mylo- 
hyoid  muscles. 


The  Lin/gual  muscle3  is  a  narrow  fasciculus  of  fibres,  situated  between 
the  insertion  of  the  hyo-glossal  and  genio-glossal  muscles,  and  extending 
from  the  hyoid  bone  to  the  tip  of  the  tongue. 

The  Sty'lo-glos'sal  muscle4  arises  from  the  extremity  of  the  styloid 
process  of  the  temporal  bone  and  from  the  stylo-maxillary  ligament,  and 
descends  to  expand  in  the  side  of  the  tongue  externally  to  the  hyo-glossal 
muscle. 

The  genio-glossal  muscles,  when  the  mouth  is  open,  will  protrude  the 
tongue,  and  the  hyo-glossal  and  lingual  muscles  will  retract  it  again. 
The  anterior  portion  of  the  genio-glossal  muscles  when  alone  contract- 
ing will  draw  down  the  tip  of  the  tongue.  The  stylo-glossal  muscles 
draw  the  sides  of  the  tongue  upward  and  backward. 

The  arteries  of  the  tongue  are  derived  from  the  lingual  branches  of 


1  M.  hyo-glossus ;  m.  basio  glossus,  ce- 
rato-glossus,  et  chondro-glossus;  m.  hy- 
oideo-glossus;  m.  hyo-chondro-glossus ; 
m.  hypsilo-glossus. 


2  M.  genio-glossus;  m.  genio-hyo-glos- 
sus;  m.  meso-glossus  ;  m.  nonus  linguae. 

3  M.  lingualis ;    m.  basio-glossus ;   m. 
glossianus  ;  m.  longitudinalis  inferior. 

4  M.  stylo-glossus. 


THE  ALIMENTARY  APPARATUS.  285 

the  external  carotids.  The  principal  veins  are  the  ranine,  which  usually 
join  the  facial  vein  on  each  side  of  the  head.  The  nerves  are  the  lingual 
branch  of  the  inferior  maxillary,  the  lingual  branches  of  the  glosso-pharyn- 
geal,  and  the  hypoglossal  nerve.  The  former  two  supply  the  mucous 
membrane  and  papilla  of  taste ;  the  latter  supplies  the  muscular  struc- 
ture. 

THE  TEETH. 

Teeth1  have  so  close  a  relationship  with  the  nature  of  the  food  and 
the  habits  of  animals,  that  they  present  to  the  zoologist  most  important 
distinctive  characters  in  classification.  Three  different  substances  gen- 
erally enter  into  their  constitution :  cement,  a  material  resembling  bone ; 
dentine,  a  harder  material  forming  the  ivory  of  the  tooth ;  and  enamel, 
not  only  the  hardest  material  of  teeth,  but  the  hardest  of  all  organic 
substances.  In  the  grinding  teeth  of  herbivorous  animals,  as  the  horse, 
ox,  and  elephant,  the  three  substances  alternate  with  one  another  in  such 
a  manner  that,  as  the  teeth  are  worn,  an  uneven  triturating  surface  is 
always  preserved.  In  carnivorous  and  omnivorous  animals,  as  the  cat, 
dog,  and  hog,  the  body  of  the  teeth  is  composed  of  dentine,  while  the 
crown  or  exposed  part  is  capped  with  enamel,  and  the  roots  are  covered 
with  a  thin  film  of  cement. 

The  teeth  are  properly  appendages  of  the  mucous  membrane  of  the 
alimentary  canal,  and  are  developed  from  it.  They  are  inserted  into  a 
portion  of  the  skeleton  so  as  to  give  them  a  firmly-fixed  position.  In 
birds  and  turtles  we  find  their  place  on  the  jaws  occupied  by  a  corneous 
bill,  which,  like  nails  and  hairs,  is  an  appendage  of  the  skin.  In  grami- 
nivorous birds,  as  the  common  fowl,  pebbles  swallowed  with  the  food  are 
a  substitute  for  teeth.  The  gizzard,  which  is  a  powerfully  muscular 
stomach  with  a  thick  epidermis-like  lining,  triturates  the  hard  food 
through  the  aid  of  the  pebbles. 

Man  and  almost  all  other  mammals,  in  the  course  of  life,  are  provided 
with  two  sets  of  teeth,  of  which  the  first  are  the  temporary  or  milk 
teeth;  the  second,  the  permanent  teeth.  Reptiles  and  fishes  are  pro- 
vided with  numerous  sets,  which  succeed  one  another  through  life. 

The  teeth  are  divided  into  four  kinds,  named  inci'sors,  canines',  pre- 
mo'lars  or  bicus'pids,  and  molars. 

The  protruding  portion  of  the  teeth  is  named  the  crown  or  body;2 
the  portion  inserted  into  the  alveoli  or  sockets  of  the  jaws,  is  the  fang 

1  Sing.:  dens;  odous  ;  pl.:dentes;  odontes  ;  mordices.  2  Corona. 


286  THE  ALIMENTARY  APPARATUS. 

or  root;1  and  the  slightly  constricted  portion  clasped  by  the  gums,  is  the 
neck,2  The  crown  varies  in  form  in  the  different  kinds  of  teeth.  The 
fang  gradually  tapers  to  its  extremity,  and  is  firmly  attached  to  the  sides 
of  the  alveolus,  in  which  it  is  inserted,  by  fibrous  tissue  continuous  with 
the  periosteum  of  the  jaws  and  the  submucous  tissue  of  the  gums.  At 
the  neck  of  the  tooth  a  slight  accumulation  of  this  tissue  constitutes  the 
dental  ligament. 

The  teeth  have  in  their  interior  a  small  hollow  called  the  pulp  cavity,3 
which  has  the  general  form  of  the  teeth,  and  contains  a  soft,  highly  sen- 
sitive, and  vascular  structure  named  the  pulp.4  This  receives  its  blood- 
vessels and  nerves  through  a  narrow  canal5  opening  at  the  extremity  of 
the  fangs. 

The  teeth  in  each  jaw  form  an  unbroken  arch,  which  is  rarely  the  case 
in  any  of  the  inferior  animals.  The  upper  arch  is  larger  than  the  lower 
one,  and  projects  slightly  beyond  it.  This  difference  is  mainly  due  to 
the  obliquity  fqrward  of  the  upper  front  teeth,  while  the  corresponding 
ones  below  are  vertical,  and  those  behind  slightly  inclined  inward.  When 
the  jaws  are  shut,  the  upper  incisors  inclose  those  below,  while  the  suc- 
ceeding upper  teeth  alternate  with  those  below ;  the  triturating  surfaces 
of  the  molars  being  in  contact. 

CHARACTERS  OF  THE  PERMANENT  TEETH. 

The  Permanent  teeth6  are  thirty-two  in  number,  sixteen  in  each  jaw, 
or  eight  on  each  side  of  each  jaw,  as  follows  :  two  incisors,  one  canine, 
two  premolars,  and  three  molars.  Occasionally  there  is  a  diminution  or 
an  increase  in  the  number.  When  there  are  supernumerary  teeth,  they 
are  usually  small,  and  provided  with  a  single  fang. 

The  Inci'sors,7  eight  in  number,  are  the  four  front  teeth  of  each  jaw, 
and  are  so  named  from  their  being  adapted  to  cutting  or  biting  the 
food.  Their  crown  is  wedge-shaped  or  chisel-like,  being  convex  in 
front,  beveled  behind,  and  triangular  at  the  sides.  The  cutting  edge  at 
first  is  narrow,  and  provided  with  three  small  tubercles,  but  these  are 
soon  obliterated  from  use,  and  the  edge  gradually  widens.  The  fang  is 
long,  conical,  and  compressed  at  the  sides. 

1  Radix.  6  Second  teeth;  last  teeth;  dentes  per- 

2  Cervix ;  collum.  manentes ;  d.  serotini. 

3  Cavitas  pulpae;    cavum  dentis;  an-           7  Incisive   teeth:    dentes   incisivi,   or 
trum  dentale.  incisores;   d.  primores;    d.  tomici,  raso- 

4  Pulpa ;  blastema  dentis.  sores,  gelasini,  ctenes,  or  dichasteres. 

5  Canalis  radicis,  or  dentalis. 


THE  ALIMENTARY  APPARATUS. 


287 


The  upper  incisors  are  larger  than  the  lower  ones,  and  of  the  former 
the  central  incisors1  are  the  larger,  while  the  lateral  ones  are  the  larger 
in  the  case  of  the  lower  incisors.  The  upper  incisors  are  directed  down- 
ward and  forward,  while  the  lower  ones  occupy  a  vertical  position. 


FIG.  205. 


UPPER  AND  LOWER  PERMANENT  TEETH,  EXTERIOR 

VIEW.  1,  first  incisors ;  2,  canines ;  3,  first  premo- 
lars ;  4,  middle  molars. 


LATERAL  VIEW  of  the  same  teeth,  as  in  the  pre- 
ceding figure. 


The  Canine'  teeth,2  four  in  number,  are  larger  than  the  incisors,  and 
succeed  them  in  position,  one  on  each  side  above  and  below.  Their 
crown  is  blunt,  conical,  beveled  behind,  and  becomes  more  blunt  from 
attrition.  Their  fang  is  conical,  compressed  at  the  sides,  and  longer 
than  in  any  of  the  other  teeth.  It  is  also  marked  laterally  by  a  slight 
furrow,  as  if  indicating  a  disposition  to  divide  into  two. 

The  upper  canines,  commonly  called  eye  teeth,  are  larger  and  longer 
than  the  lower  ones,  which  are  commonly  known  as  the  stomach  teeth. 

In  carnivorous  animals  the  canine  teeth  are  remarkable  for  their 
length  and  strength,  and  are  admirably  adapted  to  seizing,  retaining, 
and  tearing  living  prey.  From  their  conspicuous  character  in  the  canine 
or  dog  tribe  they  have  received  their  name. 

The  Premo'lars,  or  bicus'pid  teeth,3  eight  in  number,  succeed  the  ca- 


1  Butter  teeth. 

2  Cuspid  teeth ;  dentes  cuspidati ;  ca- 
nini;  angulares,  or  laniarii;  d.  columel- 


lares ;  oculares,  or  mordentes ;  cynodon- 
tes ;  pug  teeth. 

3  Small  molars;  dentes  bicuspidati;  d. 
buccales. 


288  THE   ALIMENTARY   APPARATUS. 

nines  in  position,  two  on  each  side  above  and  below.  Their  crown  is 
cubical  with  rounded  borders,  prominently  convex  externally  and  in- 
ternally, and  less  so  or  flattened  at  the  sides.  The  triturating  surface 
has  a  prominent  border  elevated  before  and  behind  into  a  pair  of  tuber- 
cles, of  which  the  outer  one  is  the  larger  and  higher.  The  fang  is  coni- 
cal, much  flattened,  and  deeply  grooved  at  the  sides,  indicating  a  dispo- 
sition to  divide.  The  upper  premolars  are  larger  than  the  lower  ones, 
and  their  fang  is  usually  more  or  less  divided  into  two,  especially  that 
of  the  second  upper  premolar. 

The  Mo'lars,1  twelve  in  number,  are  next  in  succession  to  the  premo- 
lars, three  on  each  side  above  and  below.  They  are  commonly  known  as 
grinders  or  jaw  teeth;  and  have  a  large,  cuboidal  crown,  with  low, 
rounded  sides  and  borders,  but  are  generally  least  convex  laterally,  or  are 
even  flattened  in  this  position.  In  the  upper  molars  the  grinding  surface 
is  rhomboidal,  with  a  prominent  border,  elevated  at  the  four  angles  into 
as  many  tubercles.  In  the  lower  molars,  the  grinding  surface  is  nearly 
oblong  square,  with  a  prominent  border  elevated  into  five  tubercles.  The 
lower  molars  have  a  pair  of  conical  fangs  placed  side  by  side,  and  much 
compressed  and  deeply  grooved  laterally.  The  upper  molars  have  three 
conical  fangs,  two  external  and  one  internal ;  the  latter  being  the  larger 
and  grooved,  as  if  disposed  to  divide. 

The  molars  slightly  decrease  in  size  from  first  to  last,  and  the  lower 
ones  are  larger  than  the  upper  ones.  The  last  of  the  series,  from  its 
comparatively  late  appearance  in  life,  is  named  the  wisdom  tooth.2  It 
is  liable  to  considerable  variation  in  size  and  form,  more  especially  in 
the  case  of  the  upper  one.  Its  fangs  are  usually  more  or  less  confluent 
into  a  single  cone. 

CHARACTERS  OF  THE  TEMPORARY  TEETH. 

The  Temporary  or  milk  teeth3  are  twenty  in  number,  ten  in  each  jaw, 
or  five  on  each  side  of  each  jaw,  as  follows :  two  incisors,  one  canine,  and 
two  molars. 

The  incisors  and  canines  correspond  in  number  with  those  of  the  per- 
manent set,  which  they  also  resemble  in  form ;  but  they  are  smaller,  and 
the  crowns  are  broader  in  proportion  to  their  length. 

1  Denies  molares  ;  large  molars;   true  2  Dens  sapientiae  ;  d.  serotinus;  d.  so- 

molars;  denies  multicuspidati;  d.  maxil-  phroreticus;  d.  sophronista;  wit  tooth; 

lares,  clavales,  or  gomphii ;  molse ;  my-  last  tooth. 

lodontes ;  mylacri ;  momisci ;  cheek  3  Dentes  lactei ;  d.  caduci ;  d.  tempo- 
teeth  ;  axle  teeth  ;  wall  teeth ;  log  teeth ;  rarii ;  deciduous  teeth ;  primary,  or 
grinding  teeth.  shedding  teeth. 


THE  ALIMENTARY  APPARATUS. 


289 


No  premolars  belong  to  the  temporary  set  of  teeth.     The  molars  are 
eight  in  number,  succeeding  the  canines  in  position,  two  on  each  side 

above  and  below. 

FIG.  207. 

1  345 


FIG.  208. 


TEMPORARY  TEETH  OF  ONE  SIDE.  1,  2,  upper  and  lower  incisors;  3,  upper  and  lower  canine;  4,  5,  upper 
and  lower  molars;  6,  7,  triturating  surface  of  the  lower  molars;  8,  9,  triturating  surface  of  the  upper 
molars. 

STRUCTURE  OF  THE  TEETH. 

On  splitting  a  tooth  longitudinally,  the  exposed  surface  exhibits, 
besides  the  pulp  cavity,  three  different  sub- 
stances. The  greater  portion  of  the  tooth 
appears  to  be  composed  of  a  yellowish-white 
substance,  which  is  called  dent'ine;  the  crown 
is  capped  with  a  harder  and  whiter  layer, 
named  the  enam/el;  and  a  thin,  translucent 
investment  to  the  fang  is  the  cement'. 

The  Dent'ine,  or  ivory,1  forms  the  principal 
bulk  of  the  tooth,  giving  to  it  the  general 
shape,  and  containing  the  pulp  cavity.  It 
is  yellowish-white,  and  has  the  appearance 
of  dense  bone,  which  it  further  resembles  in 
chemical  composition.  It  consists  of  about 
twenty-eight  parts  of  bone  cartilage  and 
seventy-two  parts  of  earthy  matters ;  mostly 
phosphate  of  lime,  with  a  little  carbonate  of 
lime. 

In  thin  section,  beneath  the  microscope,  the 


VERTICAL  SECTION  OF  A  MOLAR  TOOTH. 
moderately  magnified.  1,  enamel,  the 
lines  of  which  indicate  the  arrange- 
ment of  its  columns;  2,  dentine,  the 
lines  indicating  the  course  of  its  tu- 
bules; 3,  thin  lamina  of  the  dentine 
forming  the  wall  of  the  pulp  cavity, 
the  dots  indicating  the  orifices  of  the 
dentinal  tubules ;  4,  cement. 


1  Ebur ;    substantia  ossea,  or   eburnea ;    tooth  bone ;    proper  tooth  substance ; 
osseous  substance. 

19 


290 


THE  ALIMENTARY  APPARATUS. 


dentine  is  found  to  be  composed  of  a  translucent,  amorphous  substance, 
pervaded  with  a  multitude  of  fine  canals,  possessing  distinct  walls  from  the 
intervening  material.  The  canals,  named  dent/inal  tu/bules,1  commence 
with  open  orifices  at  the  surface  of  the  pulp  cavity,  and  radiate  from  thence 
to  the  periphery  of  the  tooth.  They  have  a  general  parallel  and  gently 
waving  or  undulating  course.  As  they  proceed  outwardly,  they  divide 
into  several  principal  branches,  pursuing  the  same  general  parallel  course 


FIG.  209. 


Fro.  210. 


Fig.  209.  VERTICAL  SECTION  OF  THE  FANG  OF  A  CANINE  TOOTH,  exhibiting  the  structure  of  the  dentine  and 
cement.  1,  inner  extremities  of  the  dentinal  tubules  ;  2,  outer  extremities  of  the  tubules,  terminating  in 
interspaces  at  the  boundary  of  the  dentine;  3,  cement;  4  lacunoe  like  those  of  bone.  Highly  magnified. 

Fig.  210.  SECTION  OF  DENTINE,  cutting  across  the  direction  of  its  tubules,  very  much  magnified.  The 
tubules  are  seen  to  have  thick  walls,  distinct  from  the  intervening  material. 

to  one  another.  They  also  gradually  become  narrower,  and  give  off  in- 
numerable, fine,  divergent  branches,  which  anastomose  with  one  another. 
The  walls  of  the  tubules  are  nearly  as  thick  as  their  calibre,  which,  in 
the  fresh  tooth,  is  filled  with  a  colorless  liquid,  replaced  by  air  in  dried 
specimens.  In  consequence  of  the  latter  condition,  the  dried  microscopic 
sections  of  teeth,  when  viewed  by  transmitted  light,  appear  pervaded 
by  black  lines ;  while  by  reflected  light,  the  same  lines  appear  silvery 
white. 

FIG.  211.  FIG.  212. 


THREE  ENAMEL  COLUMNS,  highly  magnified ;  ex- 
hibiting the  six-sided  prismatic  and  waving  charac- 
ter. 


SECTION  OF  ENAMEL,  highly  magnified,  at  right 
angles  to  the  course  of  its  columns;  exhibiting  the 
six-sided  character  of  the  latter. 


The  Enam'el2  is  the  glistening-white  or  bluish-white  substance  invest- 
ing the  crowns  of  the  teeth.  It  is  thickest  on  the  triturating  surface, 
and  gradually  diminishes  toward  the  neck,  where  it  terminates  by  a 


1  Canaliculi  dentium. 

2  Substantia   vitrea ;    s.   adamantina ; 


s.  filamentosa;  cortex;  c.  striata;  crusta 
adamantina ;  nitor  dentium. 


THE   ALIMENTARY   APPARATUS.  291 

sharply  defined  edge.  As  previously  mentioned,  enamel  is  not  only  the 
hardest  of  all  the  dental  structures,  but  it  is  the  hardest  of  all  organized 
substances.  In  chemical  composition  it  consists  of  only  five  parts  of  bone 
cartilage,  with  ninety-five  parts  of  earthy  matters,  mostly  phosphate  of  lime. 

Viewed  with  the  microscope,  enamel  is  found  to  consist  of  solid,  hexa- 
hedral  columns,  resting  with  one  extremity  on  the  dentine  of  the  crown, 
and  with  the  other  extremity  free.  The  columns  are  not  straight,  but 
undulating  in  their  course ;  and  at  the  sides  they  present  a  faint,  trans- 
versely striated  appearance. 

The  arrangement  of  the  enamel  columns  is  the  most  favorable  that 
could  have  been  adopted  to  prevent  their  detachment  and  rapid  abrasion  ; 
though  this  arrangement,  together  with  the  great  deficiency  of  bone  car- 
tilage, renders  the  enamel  brittle,  and,  under  extremes  of  temperature, 
*to  which  it  is  often  subjected  in  the  use  of  hot  and  cold  food,  it  is  liable 
to  crack. 

The  exterior  surface  of  the  unworn  enamel,  when  treated  with  hydro- 
chloric acid,  so  as  to  remove  its  calcareous  salts,  separates  in  the  form  of 
a  thin,  homogeneous  membrane,1  which,  though  it  is  intimately  blended 
with  the  exterior  ends  of  the  enamel  columns,  appears  to  be  an  inde- 
pendent structure. 

The  Cement'2  is  a  very  thin  layer  of  osseous  substance  investing  the 
fangs  of  the  teeth,  commencing  at  the  neck,  and  gradually  becoming 
thicker  to  the  extremities  of  the  fangs.  In  the  latter  position,  in  the 
teeth  of  old  persons,  it  frequently  becomes  much  increased  in  thickness, 
and  sometimes  forms  a  nodular  mass.  Like  true  bone,  the  cement  con- 
tains branching  lacunae,  but  vascular  canals  pervade  it  only  when  it 
becomes  much  thickened. 

The  teeth,  like  the  epithelium  of  a  mucous  membrane,  are  entirely 
non- vascular,  and  their  fluids  are  obtained  by  imbibition  from  the  dental 
pulp  and  the  periosteum  of  the  fangs. 

The  Dent/al  pulp3  is  a  soft,  translucent,  reddish-white  substance,  filling 
the  pulp  cavity  of  the  teeth.  It  is  composed  of  an  exterior  layer  of  nu- 
cleated cells,  with  an  interior  mass  of  indistinctly  defined  areolar  tissue, 
mingled  with  many  nuclei,  and  containing  an  abundant  colorless  liquid. 
Highly  sentient  and  vascular,  its  nerves  and  blood-vessels,  entering  the 
fine  aperture  at  the  ends  of  the  fangs,  are  derived  from  the  dental  nerves 
of  the  trifacial,  and  the  dental  arteries  of  the  internal  maxillary  artery. 

1  Nasmyth's  membrane ;  cuticle  of  the      crusta  petrosa ;  cortical  substance  ;  sub- 
enamel  ;  skin  of  the  teeth.  stantia  ostoidea. 

2  Cementum ;  crusta  ostoides  radicis  ;  3  Pulpa  dentis. 


292 


THE  ALIMENTARY  APPARATUS. 


DEVELOPMENT  OF  THE  TEETH. 

The  temporary  teeth  commence  their  development  from  the  sixth  to 
the  tenthXonth  of  embryonic  life,  originating  in  a  corresponding  num- 
ber of  papillae  from  the  bottom  of  the  dental  groove,1  which  is  a  semi- 
circular inflection  of  the  mucous  membrane  at  the  margin  of  the  gums. 
Processes2  from  the  dental  groove  gradually  inclose  the  papillae  in  sepa- 
rate compartments,  which  contract  in  the  course  of  the  fourth  month, 
and  include  the  papillae  in  distinct  cavities,  named  the  dental  sacs.  The 

FIG.  213. 


DIAGRAM  OF  THE  MODE  OF  DEVELOPMENT  OF  THE  TEETH,  a,  section  across  the  dental  groove ;  fc.  papilla 
developed  in  the  latter;  c,  the  groove  deepened  and  processes  forming  which  ultimately  close  it;  rf,  the 
groove  becoming  closed ;  e,  dental  sac  containing  a  dental  pulp,  which  is  the  rudiment  of  the  crown  of  a 
temporary  incisor ;  the  cavity  above  is  reserved  for  a  permanent  incisor ;  /,  the  crown  of  the  temporary 
incisor  fully  formed,  and  the  reserved  cavity  for  the  permanent  tooth  moving  backward ;  g,  fang  of 
the  temporary  incisor  produced,  and  origin  of  the  dental  papilla  of  the  future  permanent  tooth;  h,  erup- 
tion of  the  temporary  incisor,  and  the  alveoli  produced  for  both  teeth ;  t,  the  temporary  incisor  occupy- 
ing its  functional  position,  and  the  crown  of  the  permanent  incisor  developed. 

papillae,  now  called  dental  pulps,  gradually  assume  the  form  and  size  of 
the  crowns  of  the  future  teeth,  and  are  defined  by  a  delicate  basement 
membrane.3  The  enlarging  dental  sacs,  closely  applied  to  the  included 
pulps,  also  undergo  a  change  in  structure  ;  and  they  are  supplied  with 
blood-vessels  from  the  dental  arteries  as  well  as  from  those  of  the  gums. 
From  the  fifth  to  the  eighth  month  of  foetal  life  the  dental  pulps  com- 
mence transformation  into  dentine  by  the  deposit  of  calcareous  salts. 
This  transformation  begins  at  the  summit  of  the  pulps  and  proceeds 
toward  their  base,  and  from  without  inwardly. 


1  Primitive  dental  groove. 


Opercula. 


Membrana  praeformativa. 


THE  ALIMENTARY  APPARATUS.  293 

While  this  process  is  going  on,  the  thick  internal  layer  of  the  dental 
sacs,  named  the  enamel  organ,1  undergoes  transformation  into  enamel, 
from  within  outwardly. 

The  crown  of  the  tooth  being  produced,  the  dental  pulp  now  grows 
in  length,  and  as  it  gradually  develops  the  shape  of  the  future  fang,  it 
is  transformed  into  dentine,  from  without  inwardly,  and  from  the  base 
toward  the  end  of  the  fang. 

The  lengthening  of  the  fang  occasions  the  eruption  or  so-called  cut- 
ting of  the  teeth,2  in  which  process  the  latter  burst  their  sacs  and  pro- 
trude from  the  gums. 

The  eruption  of  the  temporary  teeth.3  occurs  after  birth,  during  the 
period  between  six  months  and  two  and  a  half  years ;  usually  in  the 
following  order,  the  lower  teeth  generally  taking  precedence  of  the  upper 
ones  : — 

The  central  incisors  from  the  sixth  to  the  eighth  month ; 

The  lateral  incisors  from  the  seventh  to  the  ninth  month ; 

The  first  molars  from  the  twelfth  to  the  fourteenth  month ; 

The  canines  from  the  sixteenth  to  the  twentieth  month ; 

The  last  molars  from  the  twentieth  to  the  thirtieth  month. 

During  the  fourth  and  fifth  months  of  foetal  life,  in  the  progress  of 
development  of  the  dental  sacs  of  the  temporary  teeth,  a  corresponding 
number  of  cavities4  are  developed  in  the  dental  groove5  over  them. 
These  reserved  cavities  subsequently  become  the  dental  sacs  of  perma- 
nent teeth ;  those  of  the  upper  jaw  receding  behind  and  above  the  po- 
sition of  the  temporary  teeth ;  those  of  the  lower  jaw  receding  behind 
and  below  the  temporary  teeth.  The  dental  sacs  just  indicated  are  finally 
inclosed  in  osseous  cavities  of  the  jaws,  communicating  by  canals6  with 
the  margin  of  the  latter.  The  canals  contain  a  narrow  pedicle,7  which 
is  the  closed  and  elongated  neck  of  the  dental  sacs  continuous  with  the 
gum  behind  the  corresponding  temporary  teeth. 

The  three  permanent  molar  teeth  on  each  side,  above  and  below,  origi- 
nate in  succession  from  the  posterior  extremity  of  the  dental  groove. 

The  permanent  teeth  are  developed  from  their  dental  sacs  and  pulps 
in  the  same  manner  exactly  as  the  temporary  teeth.  Calcification  com- 
mences in  the  different  ones  from  a  period  prior  to  birth  up  to  the  twelfth 
year  subsequently. 

At  six  years,  when  the  temporary  teeth  are  usually  still  preserved,  the 


1  Organon  adamantinse.  *  Cavities  of  reserve. 

2  Teething ;  dentition ;  odontophyia.  5  Secondary  dental  groove 

3  First  dentition ;  odontia  dentionis  lactantium.         6  Itinera  dentium. 

7  Gubernaculum  dentis. 


294  THE  ALIMENTARY  APPARATUS. 

jaws  contain  besides,  the  crowns  of  all  the  permanent  teeth  except  the 
last  molars  or  wisdom  teeth.  The  subsequent  development  of  the  fangs 
of  the  permanent  teeth  causes  a  gradual  advancement  of  their  crowns 
toward  the  gums.  Those  which  come  into  contact  with  and  press 
against  the  temporary  teeth  excite  a  gradual  absorption  of  the  fangs  of 
the  latter  Continuing  to  advance,  the  permanent  teeth  detach  the 
loosened  crowns  of  the  temporary  set,  and  protrude  from  the  gums  in 
their  place.  « 

The  eruption  of  the  permanent  teeth1  and  the  shedding  of  the  tempo- 
rary set  commences  between  the  fifth  and  seventh  years  after  birth.  The 
first  permanent  molars  usually  protrude  before  any  of  the  temporary 
teeth  are  shed,  and  it  is  perhaps  partly  due  to  this  circumstance  that 
these  teeth  are  usually  the  first  to  undergo  decay.  The  course  of 
eruption  of  the  permanent  teeth  is  commonly  as  follows,  the  lower  ones 
preceding  the  upper  : — 

The  first  molars  from  the  fifth  to  the  seventh  year ; 

The  central  incisors  from  the  sixth  to  the  eighth  year ; 

The  lateral  incisors  from  the  seventh  to  the  ninth  year ; 

The  first  premolars  from  the  eighth  to  the  tenth  year ; 

The  second  premolars  from  the  tenth  to  the  twelfth  year ; 

The  canines  from  the  eleventh  to  the  twelfth  year ; 

The  second  molars  from  the  twelfth  to  the  fourteenth  year ; 

The  last  molars  or  wisdom  teeth  from  the  seventeenth  to  the  twenty- 
second  year. 

THE  PHAEYNX. 

The  Pha'rynx2  or  throat  is  the  funnel-like  cavity  occupying  the  gut- 
tural region  of  the  skull,  and  extending  from  its  base  down  to  a  level 
with  the  fifth  cervical  vertebra,  where  it  terminates  in  the  oesophagus. 
Behind  it  is  the  vertebral  column,  and  on  each  side  the  great  blood-ves- 
sels and  nerves  of  the  neck.  Communicating  with  it  in  front,  in  succes- 
sion from  above  downward,  are  the  nasal  fossae,  the  mouth,  and  the 
larynx ;  and  opening  into  it  on  each  side  of  the  nasal  fossa3  is  the  Eu- 
stachian  tube.  Its  upper  extremity  is  attached  to  the  basilar  process  of 
the  occipital  bone  ;  and  on  each  side  it  is  attached  in  succession  to  the 
petrous  portion  of  the  temporal  bone,  the  internal  pterygoid  process, 
the  pterygo-maxillary  ligament,  the  back  part  of  the  molar  ridge  of  the 
lower  jaw,  the  root  of  the  tongue,  the  hyoid  bone,  and  the  larynx.  With 
the  surrounding  parts  it  is  connected  by  areolar  tissue. 

1  Second  dentition;  odontia  dentionis  puerilis;   dedentition. 

2Pharus;   pharyngethros;    fauces;    gula;    isthmos;    laemos;   ingluvies ;    gurges; 
os  posterum ;  principium  guise ;  communis  aeris  et  nutrimentorum  via. 


THE   ALIMENTARY   APPARATUS.  295 

The  walls  of  the  pharynx  are  musculo-membranous.  Exteriorly  it  is 
provided  with  a  thin,  fibrous  investment,  which  at  its  attachment  to  the 
base  of  the  skull  assumes  a  stronger  and  more  aponeurotic  character. 
Within  this  structure  succeeds  a  moderately  thick,  muscular  layer,  sepa- 
rable into  five  pairs  of  distinct  muscles,  presently  to  be  described. 

The  lining  mucous  membrane  of  the  pharynx  is  soft  and  red,  and  is  con- 
nected with  the  muscular  layer  by  a  strong  submucous  tissue  containing 
many  glands.  As  low  down  as  the  floor  of  the  nose  the  mucous  mem- 
brane is  furnished  with  a  columnar  ciliated  epithelium,  but  in  the  lower 
portion  of  the  pharynx  it  resembles  that  of  the  mouth,  being  furnished 
with  minute  papillae  imbedded  in  a  squamous  epithelium. 

The  pharyn'geal  glands  are  of  the  racemose  and  follicular  kind  ;  the 
latter  variety  being  simple  and  compound,  having  the  peculiar  constitu- 
tion of  the  tonsils  and  follicular  glands  of  the  palate  and  tongue. 

The  blood-vessels  of  the  pharynx  are  derived  from  the  pharyngeal, 
inferior  palatine,  and  thyroid  arteries.  The  nerves  are  supplied  from 
the  glosso-pharyngeal,  pneumo-gastric,  and  sympathetic  system. 

MUSCLES  OF  THE  PHARYNX. 

The  Pal'ato-pharyn'g'eal  muscle1  originates  in  the  soft  palate,  and 
descends  within  the  posterior  half  arch  of  the  palate  to  be  inserted,  in 
conjunction  with  the  succeeding  muscle,  into  the  side  of  the  pharynx  and 
the  upper  part  of  the  thyroid  cartilage. 

The  Sty'lo-pharyn'geal  muscle2  arises  from  near  the  root  of  the  sty- 
loid  process  of  the  temporal  bone,  and  descends  between  the  superior 
and  middle  constrictors  of  the  pharynx,  to  expand  upon  the  mucous 
membrane  of  the  latter,  and  partially  to  be  inserted  into  the  upper  part 
of  the  thyroid  cartilage. 

The  Superior  Constric'tor  of  the  Pharynx3  is  a  thin,  quadrilateral 
muscle  arising  from  the  pterygo-maxillary  ligament  and  the  lower  half 
of  the  internal  pterygoid  process.  Proceeding  backward,  it  conjoins  the 
muscle  of  the  opposite  side,  and  is  prolonged  to  be  attached  to  the  ba- 
silar  process  of  the  occipital  bone. 


1  M.palato-pharyngeus;  m.  pharyngo-  3  M.  constrictor  pharyngeus  superior; 
staphylinus;  m.  staphylino-pharyngeus;  m.  cephalo-pharyngeus;  m.  glosso  pha- 
m.  thyro  pharyngo-staphylinus;  m.  hy-  ryngeus ;  m.  mylo-pharyngeus ;  m.  pte- 
pero  pharyngeus  in  part.  rygo-pharyngeus ;  m.  pterygo-syndcsmo- 

2  M.  stylo-pharyngeus;    m.  stylo-thy-  staphili-pharyngeus. 
ro-pharyngeus. 


296  THE  ALIMENTARY  APPARATUS. 

The  Middle  Constric'tor  of  the  Pharynx1  is  a  fan-shaped  muscle, 
arising  from  the  great  and  small  horns  of  the  hyoid  bone,  from  whence 
it  radiates  to  conjoin  the  muscle  of  the  opposite  side  in  the  posterior 
median  line  of  the  pharynx. 

The  lower  fibres  of  the  muscle  are  concealed  by  the  inferior  constrictor ; 
the  middle  ones  are  nearly  horizontal ;  and  the  upper  ones  overlap  the 
superior  constrictor. 

FIG.  214.  FIG.  215 


Fig.  214.  POSTERIOR  VIEW  OF  THE  MUSCLES  OF  THE  PHARYNX.  1,  vertical  section,  transversely,  of  the 
base  of  the  skull,  just  in  advance  of  the  cervical  vertebras;  2,  3,  posterior  border  and  angle  of  the  lower 
jaw  ;  4,  internal  pterygoid  muscle;  5,  styloid  process  giving  attachment  to  6,  the  stylo-pharyngeal  mus- 
cle ;  7,  larynx ;  8,  inferior  constrictor  of  the  pharynx ;  9,  middle  constrictor ;  10,  superior  constrictor. 

Fig.  215.  SIDE  VIEW  OF  THE  MUSCLES  OF  THE  PHARYNX.  1,  trachea;  2,  cricoid  cartilage;  3,  vocal 
membrane;  6,  hyoid  bone;  7,  stylo-hyoid  ligament;  8,  oesophagus;  9,  inferior  constrictor  of  the  pharynx; 
10,  middle  constrictor;  11,  superior  constrictor;  12,  portion  of  the  stylo-pharyngeal  muscle  observed  pass- 
ing into  the  interval  between  the  superior  and  middle  constrictors;  13,  upper  extremity  of  the  pharynx; 
14,  pterygo-maxillary  ligament;  15,  buccinator  muscle;  16,  oral  orbicular  muscle;  17,  mylo-hyoid  muscle. 

The  Inferior  Constrictor  of  the  Pharynx2  arises  from  the  upper  one 
or  two  rings  of  the  trachea,  the  side  of  the  cricoid  cartilage,  and  an 
oblique  line  of  the  thyroid  cartilage.  From  this  origin  it  curves  back- 
ward, expanding  in  its  course,  and  conjoins  the  muscle  of  the  opposite 
side  in  the  posterior  median  line  of  the  pharynx. 

The  inferior  fibres  of  the  muscle  are  horizontal,  and  inclose  the  com- 
mencement of  the  oesophagus ;  and  the  upper  fibres  ascend,  gradually 


1  M.  constrictor  pharyngeus  medius  ;  2  M.  constrictor  pharyngeus  inferior ; 

m.  hyo-pharyngeus  ;    m.  cerato-pharyn-  m.  lai-yngo  pharyngeus ;     m.  thyro-    et 

geus ;  m.  chondro-pharyngeus  ;  m.  syn-  crico-pharyngeus ;    m.  crico-thyro-pha- 

desmo-pharyngeus ;  m.  hyo-glosso-basi-  ryngeus. 
pharyngeus. 


THE   ALIMENTARY   APPARATUS.  297 

increasing  in  obliquity,  and  overlap  the  lower  part  of  the  middle  con- 
strictor. 

The  muscles  of  the  soft  palate,  fauces,  and  pharynx,  together  with 
those  of  the  tongue  and  the  elevators  of  the  hyoid  bone  and  larynx,  are 
concerned  in  the  action  of  deglutition,  or  swallowing. 

The  genio-glossal  muscles,  drawing  the  tongue  forward  and  upward, 
press  the  food  against  the  hard  palate,  and  from  thence  into  the  fauces. 
The  stylo-glossal  muscles  now  contract,  narrowing  the  entrance  of  the 
fauces ;  and  the  stylo-glossal  muscles  draw  the  tongue  backward  and  up- 
ward. The  soft  palate  is  drawn  upward  and  backward,  and  made  tense 
by  the  action  of  its  elevators  and  tensors.  At  the  same  time,  the  palato- 
pharyngeal  muscles  cause  the  posterior  half  arches  of  the  palate  to  ap- 
proach each  other,  leaving  only  a  small  interval,  which  is  closed  by  the 
uvula,  and  thus  the  communication  of  the  pharynx  with  the  nasal  cavi- 
ties is  cut  off.  The  pharynx  and  larynx  are  drawn  up  by  the  stylo- 
pharyngeal,  stylo-hyoid,  digastric,  genio-hyoid,  and  mylo-hyoid  muscles, 
through  which  action  the  former  cavity  is  widened,  and  the  latter  is 
closed  by  pressure  against  the  epiglottis.  The  food  received  into  the 
pharynx  is  passed  downward  into  the  oesophagus  by  the  action  of  its 
constrictors,1  after  which  the  parts  resume  their  ordinary  position. 

THE  (ESOPHAGUS. 

The  Oesoph'agus  or  gullet2  is  a  musculo-membranous  tube  descending 
from  the  pharynx  in  a  slightly  flexuose  course  through  the  neck  and  pos- 
terior mediastinal  cavity  to  the  stomach.  It  commences  on  a  level  with 
the  fifth  cervical  vertebra  and  the  cricoid  cartilage  of  the  larynx,  pro- 
ceeds downward  in  contact  with  the  vertebral  column,  and  opposite  the 
ninth  dorsal  vertebra  passes  through  the  cesophageal  orifice  of  the 
diaphragm.  In  the  neck,  the  trachea  is  in  front,  and  the  primitive  ca- 
rotid artery  on  each  side  of  it ;  in  the  thorax,  the  pericardium  is  in  front, 
the  descending  aorta  to  its  left,  and  the  azygos  vein  to  its  right.  ^ 

The  oesophagus  is  about  nine  inches  long,  and  rather  less  than  an  inch 
in  diameter.  It  is  narrowest  at  its  commencement,  gradually  widens  in 
its  descent,  but  is  slightly  constricted  as  it  passes  through  the  diaphragm, 
after  which  it  quickly  expands  into  the  stomach.  In  the  state  of  rest  it  is 
flattened  from  before  backward ;  but  when  distended,  is  cylindroid  in  shape. 

1  Musculus  sphincter  gulae. 

2Gula;  fistula  cibalis;  f.  ventriculi;  infundibulum  ventriculi ;  via  stomachi  et 
ventris;  gluttus. 


298  THE  ALIMENTARY  APPARATUS. 

The  oesophagus  is  provided  externally  with  a  thin,  fibrous  investment, 
inclosing  the  oesophageal  plexus  of  nerves,  and  adhering  to  the  contigu- 
ous parts.  Succeeding  this  investment  is  the  muscular  coat,1  which  is 
about  three-fourths  of  a  line  thick,  and  composed  of  two  layers.  The 
external  layer  consists  of  longitudinal  fibres,  which  originate  in  three 
fasciculi  from  the  cricoid  cartilage  and  inferior  constrictors  of  the 
pharynx,  and  surround  the  oesophagus  uniformly  to  the  stomach.  The 
internal  layer,  thinner  than  the  other,  consists  of  transverse  or  circular 
fibres,  continuous  with  the  inferior  constrictors  of  the  pharynx,  and  ex- 
tending to  the  stomach. 

In  the  upper  part  of  the  oesophagus  the  muscular  coat  is  exclusively 
composed  of  striated  fibres,  but  in  its  descent  unstriated  fibres  become 
mingled  with  the  latter,  and  finally  predominate. 

The  mucous  membrane  lining  the  oesophagus  is  much  paler  than  in  the 
pharynx  or  mouth,  though  it  has  the  same  structure,  being  provided  with 
minute  papilla  and  a  squamous  epithelium  which  completely  conceals  the 
latter  When  the  oesophagus  is  at  rest,  the  mucous  membrane  is  thrown 
into  slight  longitudinal  folds,  which  disappear  in  the  distended  condition 
of  the  organ.  Beneath  the  mucous  membrane  is  a  moderately  thick 
layer  of  sub -mucous  tissue,  connecting  it  to  the  muscular  coat,  and  con- 
taining some  small,  scattered,  racemose  glands,  named  from  their  position 
the  cesophage'al  glands.2 

The  blood-vessels  of  the  oesophagus  are  derived  from  the  inferior  thy- 
roid and  cesophageal  arteries.  The  nerves  are  supplied  by  the  pneumo- 
gastrics  and  the  sympathetics. 

THE  CAVITY  OF  THE  ABDOMEN. 

The  Cavity  of  the  Abdomen,  or  of  the  belly,3  the  most  extensive  space 
of  the  body,  is  occupied  by  the  greater  portion  of  the  alimentary  and 
uro-genital  apparatus.  It  is  lined  with  an  extensive  serous  membrane, 
the  peritoneum,  which,  from  its  relationship  with  the  many  viscera  it 
inves^j.  is  very  complex  in  its  arrangement. 

The  viscera  of  the  abdominal  cavity  leave  no  unoccupied  vacuity  or 
space  filled  with  air;  they  follow  the  movements  of  the  muscular  walls 
of  the  abdomen ;  and  the  enlargement  or  decrease  of  any  one  results  in 
the  displacement  of  those  around. 

In  consequence  of  the  great  extent  of  the  abdomen,  and  the  frequent 
necessity  of  referring  to  the  relative  position  of  the  organs  which  occupy 
the  different  parts  of  its  cavity,  it  is  artificially  divided  into  regions, 

1  Tunica  vaginalis  guise.         2  Glandulse  oesophageales.        3  Cavura  abdominis. 


THE  ALIMENTARY  APPARATUS. 


299 


FIG.  216. 


indicated  by  lines  drawn  on  the  abdominal  walls.  Transverse  lines  en- 
circling the  body,  one  at  the  lower  margin  of  the  thorax,  the  other  at 
the  hips  or  crest  of  the  ilium  on  each  side,  divide  the  abdomen  into 
three  zones.  A  vertical 
plane,  ascending  on  each 
side  from  the  anterior  in- 
ferior spinous  process  of 
the  ilium,  will  divide  each 
zone  into  three  parts,  and 
in  this  manner  nine  re- 
gions will  be  defined. 

Of  the  middle  regions, 
..the  upper  one  is  the  epi- 
gas'tric  region;1  the  suc- 
ceeding one,  the  umbilic- 
al region  ;2  and  the  lowest, 
the  hypogas'tric  region,3 
Of  the  lateral  regions,  the 
upper  pair  are  the  right 
and  left  hypochondriac 
regions  ;4  those  succeed- 
ing, the  lum'bar  regions  ;5 
and  the  lowest,  the  il'iac 
regions.6 

The  different  organs  oc- 
cupying these  regions  are 
as  follows : — 

The  stomach  occupies 
the  left  hypochondriac, 
epigastric,  and  a  small 
part  of  the  right  hypo- 
chondriac regions.  In  a 


CAVITY  OP  THE  ABDOMEN  LAID  OPEN,  WITH  THE  VISCERA  RETAINED 
IN  THEIR  RELATIVE  POSITION.  The  straight  lines  indicate  the  regions 
of  the  abdomen,  a,  epigastric  region ;  b,  hypochondriac  regions ; 
c,  umbilical  region ;  d,  lumbar  regions ;  e,  hypogastric  region ;  /, 
iliac  regions.  1,  flaps  of  the  abdominal  wall  turned  aside;  2,3, 
left  and  right  lobes  of  the  liver;  4,  fundus  of  the  gall-bladder;  5, 
round  ligament  of  the  liver;  6,  part  of  the  suspensory  ligament 
of  the  liver;  1,  8,  stomach;  9,  commencement  of  the  duodenum; 
10,  spleen;  11,  great  omentum  ;  12,  small  intestine;  13,  caecum; 
14,  vermiform  appendix;  15,  ascending  colon;  16,  transverse  colon; 
17,  descending  colon ;  18,  sigmoid  flexure ;  19,  epiploic  appendages; 
20,  ridges  indicating  the  course  of  the  remains  of  the  urachus  and 
umbilical  arteries ;  21,  diaphragm. 


distended  condition,  with 

the  small  intestine  empty,  it  encroaches  on  the  umbilical  region. 

The  small  intestine  forms  a  convoluted  mass,  occupying  the  umbilical 
region  and  the  contiguous  borders  of  the  surrounding  regions.     When 


1  Regio   epigastrica ;   r.  cardiaca ;    r. 
stomachica ;  epigastrium. 

2  R.  umbilicalis  ;    r.  mesogastrica ;  r. 
gastrica ;  mesogastrium. 

8  R.  hypogastrica ;  r.  pubis ;  hypogas- 
trium ;  rumen ;  venter  parvus,  or  imus. 


4  Regiones  hypochondriacae ;    r.  sub- 
cartilaginese ;  hypochondria. 

5  R.  lumbares,   or  lumbales ;   lumbi ; 
lendis ;  psoae  ;  loins ;  flanks ;  reins  ;  la- 
para. 

6  R.  iliacse  ;  inania ;  flanks. 


300  THE  ALIMENTARY  APPARATUS. 

the  viscera  of  the  pelvis  are  empty,  a  portion  of  the  small  intestine 
descends  into  that  cavity. 

The  large  intestine,  commencing  in  the  right  iliac  region,  ascends 
through  the  corresponding  lumbar  into  the  right  hypochondriac  region. 
Thence  crossing  through  the  boundary  of  the  epigastric  and  umbilical 
regions  to  the  left  hypochondriac  region,  it  descends  through  the  suc- 
ceeding lumbar  and  iliac  regions,  and  enters  the  pelvis  at  its  back  part. 

The  liver  occupies  the  right  hypochondriac  region,  and  extends  across 
the  epigastric  into  the  left  hypochondriac  region. 

The  spleen  is  situated  deeply  in  the  left  hypochondriac  region. 

The  pancreas  extends  from  one  hypochondriac  region  to  the  other, 
through  the  deep  part  of  the  epigastric  region. 

The  kidneys  occupy  the  deep  parts  of  the  lumbar  regions  or  loins.      «, 

The  urinary  bladder  occupies  the  pelvic  cavity,  but  when  distended 
rises  into  the  hypogastric  region. 

THE  PERITONEUM. 

The  Peritone'um,1  the  most  extensive  of  all  serous  membranes,  lines 
the  walls  of  the  abdomen,  and  from  them  is  reflected  upon  the  viscera. 
Like  all  serous  membranes,  it  forms  a  completely  closed  sac,  except 
that  in  the  female  the  Fallopian  tubes  communicate  with  its  cavity.  The 
viscera  are  not  included  within  the  latter,  but  are,  as  it  were,  thrust  for- 
ward from  the  back  part  of  the  abdomen,  and  inclosed  by  inflections  of 
the  peritoneum  projecting  into  its  own  cavity.  It  is  to  these  numerous 
inflections  inclosing  the  viscera  that  the  peritoneum  owes  the  complexity 
of  its  arrangement.  That  portion  of  the  membrane  investing  the  viscera 
is  named  the  vis'ceral  peritone'um,2  and  that  lining  the  abdominal  walls 
is  the  parie'tal  peritoneum  ;3  and  both  portions  on  the  interior  of  the 
peritoneal  cavity  are  in  close  contact  with  each  other.  Their  opposed 
surfaces  are  smooth  and  shining,  and  are  bathed  with  a  serous  liquid, 
which  give  the  organs  they  invest  a  slippery  feeling,  and  adapts  them 
favorably  to  move  on  one  another.  The  attached  surface  of  the  perito- 

» adheres  closely  to  the  contiguous  parts  by  thin,  connective  tissue.* 
merous  doublings  or  folds,5  associated  by  connective  tissue,  often 

1  Peritonaeum  ;  membrana  abdominis ;       subperitoneal   membrane;    retro  perito- 
velamentum  abdominale ;  tunica  praeten-       neal  membrane. 

sa ;    operimentum   praetensum ;    pagos ;  5  Omenta ;  epiploones,  ligaments,  and 

syphar;  zepach.  mesenteries.  Sing.:  omentum ;  epiploon; 

2  P.  viscerale,  or  intestinale.  rete ;  reticulum ;   dertron ;    gangamum  ; 

3  P.  parietale.  zirbus;  operimentum  intestinorum  ;  sac- 

4  Textus  cellulosus  subperitonealis,  or  cus  epiploicus ;  sagena ;  caul, 
subserosus  ;  lamina   externa  peritonei ; 


THE  ALIMENTARY  APPARATUS. 


301 


containing  much  fat,  inclose  and  sustain  the  position  of  the  viscera,  and 
likewise  include  the  blood-vessels,  lymphatics,  and  nerves  passing  to  and 
from  the  latter. 

In  tracing  the  reflections  of  the  peritoneum  from  the  abdominal  walls, 
and  from  one  organ  to  another,  in  any  direction,  its  complete  continuity 
will  be  discovered.  Thus  the  peritoneum,  in  ascending  from  the  front 
and  sides  of  the  abdominal  parietes,  invests  the  diaphragm,  and  is  thence 
reflected  to  the  liver,  producing  three  folds,  named  the  suspensory  and 
lateral  ligaments  of  the  liver.  After  inclosing  the  liver,  it  is  reflected 
as  a  doubling,  the  gas'tro-hepat'ic 
omen'tum,  from  the  transverse  fis- 
sure of  the  liver  to  the  small  curv- 
ature of  the  stomach.  Envelop- 
ing the  latter,  the  peritoneum  then 
passes  from  its  great  curvature,  and 
makes  a  quadruple  fold,  named  the 
great  omen'tum.  This  is  suspend- 
ed as  a  broad,  apron-like  process 
in  front  of  the  intestines,  and  has 
its  posterior  division  above,  inclos- 
ing the  transverse  colon.  Passing 
thence  to  the  back  of  the  abdomen, 
the  doubling  named  the  transverse 
mesoco'lon  is  produced.  Of  the  two 
layers  of  this  doubling,  the  upper 
one  proceeds  to  the  back  of  the 
liver,  there  forming  the  posterior 
part  of  its  lateral  ligaments.  The 
other  layer  of  the  transverse  meso- 
colon  descends,  and,  passing  off  lat- 
erally, incloses  the  colon  on  each 
side  and  forms  the  ascending  and 
descending  mesoco'lon.  The  peri- 
toneum, from  the  intervening  por- 
tions of  the  mesocolon  reflected 
forward  from  the  vertebral  column 
to  the  small  intestine,  forms  the 
extensive  fold  named  the  mes'en- 
tery.  From  the  root  of  the  latter 
the  peritoneum  descends  to  the  rectum,  and,  binding  this  to  the  posterior 
part  of  the  pelvis,  forms  the  mesorec'tum.  The  peritoneum  is  then  re- 
flected from  the  rectum  to  the  bladder,  or  in  the  female  to  the  uterus,  and 


DIAGRAM  OF  THE  REFLECTIONS  OF  THE  PERITONEUM 

IN  A  VERTICAL  SECTION  OF  THE    ABDOMEN,  the  peritO- 

neum  represented  by  the  thick,  black  line.  1,  up- 
per segment  of  the  sacrum ;  2,  first  lumbar  verte- 
bra ;  3,  dorsal  vertebrae  ;  4,  diaphragm ;  5,  liver ;  6, 
stomach;  7,  transverse  colon;  8,  small  intestine;  9, 
duodenum;  10,  pancreas;  11,  rectum;  12,  vagina 
and  uterus;  13,  urinary  bladder;  14,  pubis;  15, 
greater  cavity  of  the  peritoneum ;  16,  le 
17,  section  of  a  lateral  ligament  of  the 
gastro-hepatic  omentum  :  the  arrow 
communication,  at  the  right  border  of  the  latter,  of 
the  great  and  lesser  cavities  of  the  peritoneum  ;  19, 
great  omentum ;  20,  transverse  mesocolon ;  21,  me- 
sentery; 22,  recto-uterine  pouch;  23,  vesico-uterine 
pouch;  24,  portion  of  peritoneum  lining  the  ante- 
rior wall  of  the  abdomen. 


302  THE  ALIMENTARY  APPARATUS. 

thence  to  the  bladder,  and  from  this  it  ascends  to  the  anterior  wall  of  the 
abdomen. 

In  figure  217,  representing  the  course  of  the  reflections  of  the  peri- 
toneum, it  would  appear  as  if  the  latter  formed  a  small  cavity1  behind 
the  stomach,  distinct  from  the  greater  peritoneal  cavity.  This  is,  how- 
ever, not  the  case,  as  the  two  communicate  by  an  aperture,  named  the 
foramen  of  Winslow,2  behind  the  right  border  of  the  gastro-hepatic 
omentum.  A  finger  passed  through  this  opening,  and  downward  between 
the  stomach  and  colon,  gains  access  to  the  space  between  the  two  divisions 
of  the  great  omentum,  or  if  in  the  new-born  child  a  blow-pipe  be  intro- 
duced at  the  aperture,  the  great  omentum  may  be  inflated,  and  then 
appears  as  a  large  and  delicate  sacculated  vesicle.  The  experiment  sub- 
sequently fails,  as  the  omentum,  in  the  progress  of  life,  becomes  per- 
forated. 

The  folds  of  the  peritoneum,  from  their  importance,  may  now  be  sep- 
arately considered. 

The  Suspensory  ligament  of  the  liver3  is  a  falciform  doubling  of  the 
peritoneum,  extending  from  the  median  line  of  the  diaphragm  to  the 
upper  surface  of  the  liver,  between  its  anterior  notch  and  its  posterior 
border,  where  it  becomes  continuous  with  the  lateral  ligaments.  Its 
anterior  extremity  is  extended  from  the  liver  to  the  umbilicus,  and  in- 
closes the  obliterated  umbilical  vein. 

The  Right  and  Left  lateral  ligaments4  of  the  liver  are  the  peritoneal 
attachments  of  the  posterior  border  of  the  liver  to  the  diaphragm.  The 
former  is  very  short,  and  though  of  two  layers,  these  are  remote  from 
each  other,  except  at  the  right  border  of  the  liver.  The  other  is  longer, 
and  suspends  the  left  lobe  of  the  liver  loosely. 

The  Suspen'sory  ligament  of  the  spleen5  is  a  doubling  of  peritoneum 
passing  from  the  diaphragm  to  the  upper  part  of  the  spleen ;  and  it  is 
continuous  with  the  left  lateral  ligament  of  the  liver. 

The  Gas'tro-hepat'ic  omen'tum6  is  a  thin  doubling  of  the  peritoneum, 

d  between  the  transverse  fissure  of  the  liver  and  the  small  cnrva- 
the  stomach.  Its  loft  border  is  short,  and  incloses  the  cardiac 
orifice.  Its  right  border  is  long,  bounds  the  foramen  of  Winslow,  and 
incloses  the  common  biliary  duct,  the  portal  vein,  and  the  hepatic  artery. 

1  Bursa  omentalis;  saccus  retro-ven-  5  L.  phrenico-lienale;  phrenico-splenic 
tricularis ;  sac  of  the  omentum.  ligament. 

2  F.  Winslovii ;  hiatus  of  Winslow.  6  Lesser  omentum ;   omentum  minus, 

3  Ligamentum  suspensorium  hepatis ;  or  gastro-hepaticum ;  gastro-hepatic  epi- 
broad  ligament ;  1.  triangulare.  ploon ;    membrana   macilentior ;    small 

4  L.  lateralia  hepatis.  epiploon. 


THE  ALIMENTARY  APPARATUS.  303 

The  Gas'tro-splen'ic  omen'tum1  is  a  doubling  of  peritoneum  passing 
from  the  cul-de-sac  of  the  stomach  to  the  hilus  of  the  spleen,  and  con- 
tains the  splenic  blood-vessels. 

The  Great  omen/turn,  or  gas'tro-col'ic  omen/turn,2  is  a  quadruple 
doubling  of  peritoneum  suspended  from  the  great  curvature  of  the 
stomach  and  transverse  colon  downward  in  front  of  the  small  intestine, 
nearly  to  the  pelvis.  It  is  a  broad,  thin,  apron-like  process,  with  its 
four  layers  inseparably  united  in  the  adult.  It  frequeii^  presents  a 
perforated,  lace-like  appearance,  crossed  with  reticular  lines  of  fat,  inc(P 
eating  the  course  of  long,  narrow  vessels,  which  are  branches  of  the 
gastro-epiploic  arteries  and  veins.  In  fat  persons  it  contains  a  large 
accumulation  of  fat.  Not  unfrequently  it  is  found  tucked  up  above  the 
small  intestine. 

The  Mes'entery3  is  a  large  doubling  of  the  peritoneum,  which  is  re- 
flected from  the  front  of  the  vertebral  column  over  the  small  intestine. 
Its  root  is  about  six  inches  wide,  and  extends  obliquely  from  the  left  side 
of  the  second  lumbar  vertebra  to  the  right  iliac  region.  From  the  ver- 
tebral column  the  mesentery  extends  about  four  inches  to  its  intestinal 
border,  which  corresponds  in  length  with  that  of  the  small  intestine  it 
involves.  Between  the  layers  of  the  mesentery  there  are  contained, 
besides  areolar  tissue  and  fat,  the  superior  mesenteric  blood-vessels  and 
their  accompanying  plexus  of  nerves,  the  lacteals,  and  numerous  lym- 
phatic glands.  I 

The  Mesoco'lon4  is  the  portion  of  peritoneum  which  binds  the  colon 
to  the  back  part  of  the  abdomen.  The  transverse  mesoco'lon5  is  a  wide 
doubling,  the  layers  of  which,  in  front,  after  inclosing  the  transverse 
colon,  become  continuous  with  the  posterior  layer  of  the  great  omentum; 
while  behind  they  diverge  over  the  position  of  the  pancreas  and  duode- 
num. The  ascending6  and  descending  mesoco'lon7  is  for  the  most  part 
so  short,  that  its  two  layers  do  not  come  into  contact  behind  the  corre- 
sponding portions  of  the  intestine,  which,  in  consequence,  are  closely 
bound  to  the  posterior  wall  of  the  abdomen.  In  the  left  iliac  region, 

1  Omentum   gastro-lienale ;  o.  gastro-  num ;  membrana  pinguis  intestinorum ; 
splenicum;  gastro-splenic  epiploon;  g.  s.  medius  intestinum  ;  lactes  ;   epichordis. 
ligament.  4  Mesenterium  crassum. 

2  Omentum  majus;  o.  gastro-colicum ;  5  Mesocolon  transversum. 

great,    or    gastro-colic    epiploon ;     rete  6  Right  lumbar  mesocolon ;  right  liga- 

ijus;  peritonaeum  duplicatum;  zirbus  ment  of  the  colon;    colic  omentum,  or 

lipinus.  epiploon ;  third  omentum,  or  epiploon. 

3  Mesenterium  ;   mesarseum ;    media-  7  Left  lumbar  mesocolon  and  iliac  mes- 

ocolon ;  left  ligament  of  the  colon. 


304  THE   ALIMENTARY  APPARATUS. 

however,  it  becomes  so  broad  as  to  suspend  the  colon  in  a  sigmoid 
flexure. 

The  Meso-rec'tum  is  an  extension  of  the  descending  mesocolon,  con- 
necting the  upper  part  of  the  rectum  closely  to  the  sacrum. 

The  Rec'to-ves'ical  folds,1  as  expressed  by  the  name,  are  two  duplica- 
tures  of  peritoneum  which  extend  between  the  sides  of  the  rectum  and 
bladder.  They  include  between  them  a  pouch  of  peritoneum,  named 
the  rec'to-ve^frcal  pouch,  which  extends  downward  between  the  rectum 
Jld  bldJddfcr,  "nearly  to  the  position  of  the  prostate  gland.  When  the 
bladder  and  rectum  are  empty,  the  recto-vesical  folds  form  together  a 
crescentic  line,  and  a  portion  of  the  small  intestine  occupies  the  recto- 
vesical  pouch. 

In  the  female,  the  pouch  just  mentioned  is  divided,  by  the  presence  of 
the  uterus  and  vagina,  into  two  portions,  which  are  named,  from  their 
position,  the  rec'to-u'terine  and  ves'ico-u/terine  pouches,  The  former 
is  the  deeper,  extending  downward  between  the  rectum  and  the  upper 
part  of  the  vagina  while  the  other  extends  between  the  body  of  the 
uterus  and  the  bladder.  Instead  of  the  recto-vesical  folds,  their  place 
in  the  female  is  substituted  by  the  rec'to-u'terine2  and  ves'ico-u'terine 
folds.3 

The  Broad  ligaments  of  the  uterus  are  two  folds  of  peritoneum  pass- 
ing from  the  sides  of  the  uterus  to  those  of  the  pelvis.  They  inclose 
the  ovaries  and  the  Fallopian  tubes. 

From  the  summit  and  sides  of  the  bladder  a  slight  fold4  of  peritoneum 
ascends  to  the  umbilicus,  and  incloses  the  obliterated  urachus  and  um- 
bilical arteries  of  the  foetus.  Likewise  a  pair  of  slight  folds5  ascend  to 
the  umbilicus,  over  the  position  of  the  epigastric  blood-vessels.  The 
latter  folds  cross  the  course  of  the  inguinal  region,  and  divide  it  into 
two  shallow  fossae,  called,  from  their  relative  position,  the  internal  and 
external  in'guinal  fossae.6  The  former  corresponds  in  position  with  the 
external  abdominal  ring,  the  latter  with  the  internal  abdominal  ring ; 
and  here  the  peritoneum  often  presents  a  short,  conical  pouch,  which 
was^bnce  continuous  with  the  vaginal  tunic  of  the  testicle.  In  the 
female,  the  pouch  just  mentioned  is  sometimes  lengthened  into  a  blind 
sac7  accompanying  the  round  ligament  of  the  uterus  a  short  distance 
into  the  inguinal  canal. 

1  Posterior  false  ligaments  of  the  mentum  suspensorium  vesicte ;  superior 

bladder  j  plicae  semilunares.  false  ligament  of  the  bladder. 

*  Posterior  ligaments  of  the  uterus;  5  Plicae  vesico-umbilicales  laterales; 

plicae  semilunares.  plicae  epigastricae. 

3  Anterior  ligaments  of  the  uterus.  6  Fovea  inguinalis  interna  et  externa. 

4  Plica  vesico-umbilicalis  media;  liga-  7  Canal  of  Nuck. 


THE  ALIMENTARY  APPARATUS. 


305 


FIG.  218. 


THE  STOMACH. 

The  Stom'ach1  is  a  large  musculo-membranous  pouch,  situated  within 
the  abdomen,  and  extending  from  the  oesophagus  to  the  small  intestine. 
It  is  the  most  capacious  portion  of 
the  alimentary  canal,  and  is  a  re- 
ceptacle in  which  the  food  is  sub- 
mitted to  the  chemical  action  of 
liquids  elaborated  in  its  walls.  It 
occupies  the  left  hypochondriac  re- 
gion extending  through  the  epigas- 
tric into  a  small  part  of  the  right 
hypochondriac  region.  Above  it 
is  the  diaphragm  and  liver;  below, 
the  transverse  colon  ;  in  front,  the 
abdominal  wall ;  behind,  the  pan- 
creas ;  to  the  right  the  liver,  and  to 
the  left  the  spleen.  In  shape  it  is 
conical,  curved  upwardly  on  itself, 
and  is  extended  obliquely  from  left 
to  right. 

The  different  parts  of  the  stom- 
ach, to  which  we  usually  refer  in 
speaking  of  the  organ,  are  its 
greater  and  lesser  extremities,  its 
greater  and  lesser  curvatures,  its 
anterior  and  posterior  surfaces,  and 
its  cardiac  and  pyloric  orifices. 

The  greater  extremity  of  the 
stomach  is  to  the  |e£t,  and  commu- 
nicates with  the  oesophagus  by  the  car'diac  orifice;2  the  lesser  ex- 
tremity, also  named  pylor'ic  extremity,3  is  to  the  left,  and  communi- 
cates with  the  small  intestine  by  the  pylor'ic  orifice.* 

The  greater  extremity  of  the  stomach  projects  several  inches  to  the 
left  of  the  oesophagus,  and  in  this  position  is  named  the  fundus.5  The 
terminal  portion  of  the  lesser  extremity,  for  about  two  inches  of  its 


THE  STOMACH  AND  INTESTINES.  1,  stomach ;  2, 
duodenum;  3,  small  intestine;  4,  termination  of 
the  ileum ;  5,  crccum ;  6.  vermiform  appendix ;  7, 
ascending  colon;  8,  transverse  colon;  9,  descend* 
ing  colon;  10,  sigmoid  flexure  of  the  colon;  11. 
rectum ;  12,  spleen. 


1  Stomachus;     ventriculus;    gaster; 
anocoelia;  nedys;  gluttupatens ;  maw. 

2  Cardia;  oesophageal  orifice;   upper, 
or   left  orifice;    os   ventriculi;    ostium 
oesophageum. 


3  Pars  pylorica. 

4  Pylorus ;  intestinal  orifice ,  lowegr,  or 
right  orifice;  ostium  duodenale. 

5  Cul-de-sac;  great  tuberosity. 


20 


306  THE  ALIMENTARY  APPARATUS. 

length,  is  slightly  constricted  from  the  rest,  and  is  named  the  pyloric 
antrum.1 

The  lesser  curvature2  of  the  stomach  is  directed  upward  and  back- 
ward, and  has  attached  the  smaller  omentum  ;  the  greater  curvature3  is 
directed  forward  and  downward,  and  has  attached  the  anterior  division 
of  the  great  omentum. 

The  anterior  surface  of  the  stomach  presents  forward  and  upward ; 
the  posterior  surface  looks  downward  and  backward,  and  is  in  contact 
with  the  diaphragm,  pancreas,  duodenum,  and  left  kidney. 

The  capacity  of  the  stomach  varies  with  the  degree  of  distention,  but 
ordinarily  it  will  contain  from  one  to  two  quarts,  and  measures  from 
nine  to  twelve  inches  long,  and  from  four  to  five  inches  in  diameter  where 
most  capacious. 

The  walls  of  the  stomach  are  composed  of  four  coats,  named  from 
their  character  serous,  muscular,  fibrous,  and  mucous,  all  of  which  adhere 
intimately  together  by  means  of  connective  tissue. 

The  serous  coat4  is  the  most  external,  and  is  derived  from  the  perito- 
neum. It  is  a  thin,  transparent  membrane  closely  investing  the  stomach, 
except  along  the  curvatures,  where  it  leaves  a  narrow  interval  occupied 
by  the  trunks  of  the  blood-vessels,  lymphatics,  and  nerves  of  the  organ. 

The  muscular  coat5  is  composed  of  three  layers  of  pale-red,  unstriated 
muscular  fibres,  pursuing  different  directions.  The  external  layer  con- 
sists of  longitudinal  fibres  continuous  with  those  of  the  oesophagus,  from 
which  they  radiate  on  the  stomach.  They  are  most  numerous  along  the 
curvatures,  especially  the  lesser  one,  and  are  thinly  scattered  on  the  an- 
terior and  posterior  surfaces.  The  middle  layer,  more  uniform  and 
important  than  the  former,  consists  of  circular  fibres.  Commencing 
thinly  at  the  fundus,  they  gradually  accumulate  toward  the  pyloric  ex- 
tremity, and  at  the  pyloric  orifice  form  a  thick  fasciculus  named  the 
pylor'ic  sphinc'ter.6  The  internal  layer  consists  of  oblique  fibres,  con- 
tinuous with  the  circular  fibres  of  the  oesophagus.  They  form  a  wide 
band  embracing  the  cardiac  orifice  on  the  left,  and  spreading  obliquely 
downward  and  to  the  right  on  the  anterior  and  posterior  surfaces  of  the 
stomach. 

The  fibrous  coat7  is  a  thick,  submucous  tissue,  forming  an  extensible 
layer  upon  which  the  strength  of  the  stomach  mainly  depends. 

1  Antrum  pylori,  or  pyloricum;  lesser  *  Tunica  serosa. 

cul-de-sac;  lesser  tuberosity.  5  Tunica  musculosa;  stratum  muscu- 

2  Curvatura  superior;  superior,  or  dia-  lare. 
phragmatic  margin.  6  Sphincter  pylori. 

3  Curvatura  inferior;  inferior,  or  colic  7  Tunica  fibrosa;  t.  nervosa,  or  nervea. 
margin. 


THE  ALIMENTARY  APPARATUS. 


307 


The  mucous  coat1  or  lining  membrane  of  the  stomach  is  soft  and  pulpy 
to  the  touch,  and  is  of  a  pale-pinkish  ash  color.  Under  excitement  it 
becomes  more  reddened,  as  during  digestion ;  and  in  inflammation  it 
assumes  a  deep-red  hue.  It  is  thin  at  the  fundus,  and  gradually  thickens 

FIG.  219. 


FIG.  220. 


WRINKLED  OR  RUGOUS  SURFACE  OF  THE  MUCOUS  MEMBRANE  OF  THE  STOMACH.    1,  wrinkles,  or  superficial  folds ; 

2,  mammillated  surface. 

toward  the  pyloric  extremity,  where  it  is  from  three-fourths  of  a  line  to 
one  line  in  thickness.  In  the  latter  position,  ordinarily,  it  presents  nu- 
merous contorted  reticular  ridges  or  wrinkles,2  the  larger  of  which  are 
longitudinal,  and  gradu- 
ally fade  away  toward  the 
fundus  of  the  stomach. 
These  ridges  multiply  and 
increase  in  size  with  the  s'lJ^^^^Wpi"  SW. 

ft  ,  •  /»  >'*.V  •4:*^*'^f^3HP5P^»?f^5lB^»1r--*'v1'c3-f-!><;,  ^ '  5^"*  <'**-*,V^*  .>§•'• 

extent  ot  contraction  of 
the  organ,  and  decrease 
or  even  disappear  with 
its  distention. 

At  the  pyloric  orifice  a 
thick,  circular  fold,  or 
sometimes  a  pair  of  cres- 
centic  folds,  acts  the  part 
of  a  valve,  and  hence  is 
named  the  pylor'ic  valve.3 
It  contains  the  thick  mus- 
cular fasciculus  constituting  the  pyloric  sphincter. 

1  Tunica  mucosa;  erusta  villosa  ventriculi ;  gastro-mycoderis. 

2  Rugae ;  plicae.  s  Valvula  pylori. 


MAMMILLA  OF  THE  MUCOUS  MEMBRANE  OF  THE  STOMACH,  moder- 
ately magnified,  exhibiting  the  orifices  of  the  gastric  glands. 


308 


THE  ALIMENTARY  APPARATUS. 


The  free  surface  of  the  gastric  mucous  membrane  exhibits  a  feebly 
mammillated  appearance,  well  represented  in  figure  219;  and  it  is 
everywhere  minutely  punctured  by  the  orifices  of  glands.  It  is  pro- 
vided with  a  columnar  epithelium,  which  commences  at  the  cardiac 
orifice  and  subsequently  continues  throughout  the  remainder  of  the  ali- 
mentary canal. 

The  gastric  glands1  are  tubular,  and  closely  set  upright  in  the  thick- 
ness of  the  mucous  membrane.  They  are  generally  simple,  nearly 
straight  or  slightly  tortuous,  and  gradually  increase  in  length  from  the 
cardiac  toward  the  pyloric  orifice,  to  which  circumstance  is  due  the  dif- 
ference in  thickness  of  the  mucous  membrane  in  the  same  direction. 
Some  of  the  glands,  both  in  the  vicinity  of  the  cardiac  and  pyloric  orifices, 

FIG.  222. 


SMALL  PORTION  OF  THE  MUCOUS  MEMBRANE  OF  THE 
STOMACH,  WITH  THE  IMBEDDED  GASTRIC  GLANDS.  1, 
the  glands ;  2,  orifices  of  the  glands ;  3,  epithelium 
of  the  mucous  membrane;  moderately  magnified. 

are  compound,  consisting  of  a  main 
tube  dividing  at  bottom  in  from  two 
to  four  branches. 

Many  of  the  gastric  tubular 
glands  are  lined  throughout  with 
a  columnar  epithelium,  not  differ- 
ing from  that  of  the  mucous  mem- 
brane of  the  stomach.  Most  of  them,2  however,  are  provided  in  their 
deeper  part  with  comparatively  large,  rounded  or  polyhedral  cells,3 
which  gradually  merge  toward  the  orifices  of  the  glands  info  columnar 
epithelial  cells. 

Besides  the  tubular  glands,  the^  stomach  contains  at  its  pyloric  end  a 
few  minute  racemose  glands ;  and  not  unfrequently  in  the  same  position 
there  may  be  detected  a  few  small,  rounded,  whitish  bodies,  resembling 
the  solitary  glands  of  the  intestines. 


A  GASTRIC  GLAND,  highly  magnified.  1,  large 
nucleated  cells  at  the  bottom  of  the  gland,  gradu- 
ally merging  2  into  the  columnar  cells  3,  at  the 
upper  part  of  the  gland. 


1  Gastric  follicles;  glandulae  gastricae. 


Peptic  glands.  3  Peptic  cells. 


THE  ALIMENTARY  APPARATUS. 

The  stomach  is  very  vascular,  the  blood-vessels  reaching  it  along  the 
line  of  attachment  of  its  omenta.  The  gastro-epiploic  arteries  together 
form  an  arch  along  the  greater  curvature  ;  the  coronary  and  pyloric 
arteries  form  a  second  along  the  lesser  curvature,  and  the  short  gastric 
arteries  reach  the  fundus.  The  branches  from  these  vessels  diverge  to 
the  surfaces  of  the  stomach,  and  form  together,  between  its  coats,  a  vas- 
cular net,  from  which  the  capillary  nets  of  the  serous,  muscular,  and 
mucous  coats  originate.  The  veins  correspond  with  the  arteries  and 
pursue  the  same  course.  The  lymphatics  are  likewise  numerous ;  their 
trunks  also  running  along  the  curvatures.  The  nerves  are  derived  from 
the  terminal  portion  of  the  pneumogastric  and  the  solar  plexus  of  the 
sympathetic  nerves. 

The  liquid  elaborated  by  the  glandular  structure  of  the  mucous  mem- 
brane is  named  the  gastric  juice.1  Free  from  foreign  matters  derived 
from  the  food,  it  is  a  clear,  colorless  liquid,  rendered  slightly  viscid  from 
the  mixture  of  mucus,  and  has  a  decidedly  sour  taste.  It  consists  of 
water  holding  in  solution  a  peculiar  nitrogenized  principle  named  pep- 
sin,2 free  chlorohydric  and  lactic  acids,  and  a  number  of  chloride  and 
phosphatic  salts.  Its  operation  consists  mainly  in  the  solution  of  albu- 
minoid substances,  such  as  flesh,  cheese,  eggs,  and  the  gluten  of  vege- 
tables. 

THE  SMALL  INTESTINE. 

The  Small  intes'tine3  is  a  cylindrical  and  much  convoluted  tube,  occu- 
pying the  umbilical  region  and  continuous  borders  of  the  surrounding 
regions,  and  suspended  by  the  mesentery  from  the  vertebral  column.  It 
measures  about  twenty-five  feet  in  length,  and  from  one  to  one  and  three- 
quarters  of  an  inch  in  diameter ;  becomes  slightly  narrower  in  its  de- 
scent ;  and  terminates  by  joining  the  large  intestine.  It  is  divided  into 
three  portions :  the  duodenum,  jejunum,  and  ileum,  and  although 
there  is  no  distinct  separation  between  these,  each  presents  some  pecu- 
liarity of  character. 

The  Duode'num,4  as  expressed  by  the  name,  is  about  twelve  fingers'- 
breadth  in*  length,  and  it  is  the  widest  portion  of  the  small  intestine. 
Commencing  at  the  pyloric  orifice,  it  ascends  to  the  right  and  backward, 
until  it  reaches  the  neck  of  the  gall-bladder.  It  then  abruptly  turns 

1  Succus  gastriciis  ;  menstruum,  or  3  Intestinum  tenue ;  i.  gracile ;  intes- 

fermentum  ventriculi ;  gastric  acid.  tines ;  small  gut ;  guts ;  enteron. 

2Gasterase;  chymosin;  the  digestive  4  Ventriculus  succenturiatus;  dodeca- 

principle.  dactylon  ;  portonarium ;  appendix,  pro- 

cessus,  or  ecphysis  ventriculi. 


310  THE  ALIMENTARY  APPARATUS. 

downward  in  front  of  the  right  kidney,  makes  another  turn  to  the  right 
side,  opposite  the  second  lumbar  vertebra,  and  terminates  in  the  jejunum. 
The  ascending  portion  of  the  duodenum  has  the  liver  and  gall-bladder 
in  front  and  above  it,  and  after  death  is  usually  found  stained,  with 
bile  exuding  from  the  latter.  The  descending  portion  has  attached  to  it, 
on  the  left,  the  head  of  the  pancreas ;  and  into  its  lower  part  the  duct 
of  the  latter,  together  with  the  common  biliary  duct,  opens.  The  trans- 
verse portion  is  behind  the  transverse  mesocolon,  and  is  attached  by 
areolar  tissue  to  the  crura  of  the  diaphragm  and  vessels  in  front  of  the 
vertebral  column.  Along  its  upper  border  is  the  pancreas,  and  the  su- 
perior mesenteric  blood-vessels  cross  from  beneath  the  latter  over  its 
termination. 

The  Jeju'num1  and  Il'eum2  are  the  remaining  portions  of  the  small 
intestine,  and  though  they  pass  insensibly  into  each  other,  the  former  is 
viewed  as  consisting  of  two-fifths,  the  latter  of  three -fifths  of  the 
length  of  the  tube.  The  jejunum  is  wider  than  the  ileum,  feels  thicker 
between  the  fingers  from  the  more  folded  condition  of  its  mucous  mem- 
brane, and  is  further  generally  characterized  by  the  absence  of  agminated 
glands.  The  ileum  terminates  in  the  right  iliac  region,  by  joining  the 
large  intestine  nearly  at  a  right  angle. 

Like  the  stomach,  the  small  intestine  has  four  distinct  coats  composing 
its  walls  :  serous,  muscular,  fibrous,  and  mucous. 

The  external  or  serous  coat,  derived  from  the  peritoneum,  adheres 
closely  around  the  intestine,  leaving  only  a  narrow  space  along  the 
attachment  of  the  mesentery  for  the  passage  of  vessels  and  nerves.  The 
duodenum  is  invested  with  peritoneum  only  at  its  extremities ;  the  de- 
scending and  transverse  portions,  for  the  most  part,  being  destitute  of  a 
serous  covering. 

The  muscular  coat  is  composed  of  two  layers  of  pale-red,  unstriated 
fibres.  The  external  layer  consists  of  thinly-scattered,  longitudinal 
fibres ;  the  internal  layer,  thicker  and  quite  distinct,  consists  of  circular 
fibres. 

The  fibrous  coat,  less  thick  than  that  of  the  stomach,  is  nevertheless 
a  strong,  extensible  layer. 

The  mucous  coat,  or  lining  membrane  of  the  small  intestine,  is 
thinner  and  redder  than  that  of  the  stomach,  and,  like  it,  possesses  a 
columnar  epithelium.  It  is  thrown  into  numerous,  transverse,  crescentic 
folds  or  doublings,  named  val'vulse  connivences.3  These  are  widest 
and  most  abundant  in  the  upper  part  of  the  small  intestine,  where  they 

1  Nestis.  2  Ileon  ;  intestinum  circumvolutum. 

3  V.  c.  Kerkringii ;  plicse  conniventes ;  Kerkringian  valves. 


THE  ALIMENTARY  APPARATUS. 


311 


FIG.  223. 


even  overlap  at  the  edges.  In  descending,  they  gradually  diminish  in 
number  and  width ;  and  in  the 
ileum  they  become  indistinct,  and 
finally  disappear.  These  folds  are 
permanent,  and  not  due  to  con- 
traction of  the  intestinal  wall. 
They  increase  the  extent  of  ab- 
sorbing and  secreting  surface,  and 
further  retard  the  passage  of  the 
food. 


The  mucous  membrane  of  the 
small  intestine,  including  its  valvula3 
conniventes,  is  everywhere  pro- 
vided with  minute  elevations,  named 
vil'li.1  These  give  to  the  surface  a 
velvety  appearance,  which  may  be  favorably  observed,  by  examining  a  por- 
tion of  intestine,  after  it  is  cleansed  from  mucus,  beneath  water.  In  the 

Fio.  224. 


SMALL  PORTION  OP  THE  MUCOUS  MEMBRANE  FROM 
THE  UPPER  PART  OF  THE  JEJUNUM,  moderately  mag- 
nified. 1,  villi.  resembling  valvulae  conniventes  in 
miniature;  2.  tubular  glands ;  their  orifices,  3,  open- 
ing on  the  free  surface  of  the  mucous  membrane ; 
4,  fibrous  tissue. 


PORTION  OF  THE  MUCOUS  MEMBRANE  FROM  THE  ILEUM,  moderately  magnified,  exhibiting  the  villi  on  its 
free  surface,  and  between  them  the  orifices  of  the  tubular  glands.  1,  portion  of  an  agminated  gland ;  2,  a 
solitary  gland ;  3,  fibrous  tissue. 

upper  part  of  the  small  intestine  the  villi  appear  as  fine,  serpentine  folds, 
frequently  interrupted  in  their  course,  and  often  conjoined  in  a  reticular 
manner.  Descending  the  intestine,  the  fold-like  villi  become  more  fre- 
quently interrupted  or  broken,  and  finally,  in  the  ileum,  they  appear  as 
flattened,  conical,  or  tongue-like  processes. 

The  villi  are  from  one-fourth  to  one-third  of  a  line  high,  and  in  struc- 
ture are  processes  of  the  intestinal  mucous  membrane.  Provided  with 
the  columnar  epithelium,  they  contain  on  their  interior  a  capillary  net  of 
vessels,  in  the  form  of  the  villi.  They  likewise  contain  the  commence- 
ment of  those  lymphatics  called  lacteals,  but  the  manner  in  which  these 
originate  has  not  been  satisfactorily  determined.  According  to  one 


1  Villi  intestinales;  fiocculi. 


312  THE  ALIMENTARY  APPARATUS. 

view,  they  commence  as  one  or  two  caecal  branches  for  each  villus ;  and 
according  to  a  second  view,  they  commence  in  a  reteform  plexus.  In 
function,  the  villi  are  most  efficient  organs  in  the  absorption  of  the  nutri- 
tive matter  of  the  food. 

Four  kinds  of  glands  are  found  in  the  mucous  membrane  of  the  small 
intestine :  the  duodVnal,  tubular,  solitary,  and  ag'minated  glands. 

FIG.  225. 


DIAGRAM  OF  THE  STRUCTURE  OF  THE  MUCOUS  MEMBRANE  OF  THE  ILEUM,  highly  magnified.  1,  epithelium 
forming  the  free  surface  of  the  mucous  membrane ;  2,  basement  membrane;  3,  fibrous  layer ;  4,  villi  cov- 
ered with  epithelium;  5,  a  villus  deprived  of  one-half  of  its  epithelium,  and  exhibiting  through  its  base- 
ment layer  the  blood-vessels  ;  6,  a  villus  partially  deprived  of  its  epithelium ;  7,  villi  totally  deprived  of 
their  epithelium,  but  retaining  their  basement  membrane;  8,  tubular  glands  imbedded  in  the  fibrous 
layer  of  the  mucous  membrane ;  9,  orifices  of  the  tubular  glands  opening  on  the  free  surface  of  the  mu- 
cous membrane  between  the  villi;  10,  section  of  a  tubular  gland,  with  its  epithelial  lining;  11,  tubular 
glands  stripped  of  the  latter,  but  retaining  their  basement  membrane ;  12,  one  of  the  glands  in  section, 
without  its  epithelium  ;  13,  capillaries  surrounding  the  orifices  of  the  tubular  glands;  14,  an  artery;  15, 
a  vein ;  16,  lymphatics  or  lacteals ;  17,  commencement  of  the  latter  within  the  villi ;  18,  capillary  blood- 
vessels of  the  villi. 

The  Duode'nal  glands1  (Brunner's)  are  small,  racemose  glands,  occu- 
pying the  submucous  tissue,  and  opening  into  the  duodenum.  They  are 
most  numerous  at  the  commencement  of  the  latter,  where  they  form  a 
nearly  continuous  layer ;  gradually  diminishing  in  number  and  size,  they 
disappear  altogether  approaching  its  termination. 

The  Tubular  glands2  are  the  most  numerous  of  those  of  the  small  in- 
testine, and  are  found  throughout  its  whole  tract.  They  are  situated 

1  Glands  of  Brunner ;  glandulge  Brunneri ;  second  pancreas. 

2  Glands,  or  follicles  of  Lieberkiilm ;  glandulse,  or  cryptte  Lieberkuhnianse ;  cryptao 


THE  ALIMENTARY  APPARATUS. 


upright  in  the  thickness  of  the  mucous  membrane,  and  open  in  the  inter- 
vals of  the  villi,  to  which  spaces  they  give  a  perforated  appearance. 
They  are  simple,  straight  glands,  provided  with  a  columnar  epithelium ; 
and  secrete  a  clear  liquid,  called  the  intestinal  juice.1 


Fio.  226. 


FIG.  227. 


PORTION  OF  THE  DUODENUM,  viewed  from  without, 
natural  size.  1,  thickness  of  the  duodenum;  2,3, 
longitudinal  and  transverse  layers  of  fibres  of  the 
muscular  coat;  4,  fibrous  coat;  5,  exterior  of  the 
mucous  membrane,  with  the  duodenal  glands  im- 
bedded. 


A   VERTICAL    SECTION    OP    THE    DUODENUM,    highly 

magnified.  1,  a  fold-like  villus;  2,  epithelium  of 
the  mucous  membrane ;  3,  orifices  of  the  tubular 
glands,  4;  5,  orifice  of  a  duodenal  racemose  gland, 
6;  7,  two  vesicles  of  the  latter,  more  highly  magni- 
fied, exhibiting  the  epithelial  cells  lining  their  in- 
ternal surface. 


The  Solitary  glands2  are  minute,  whitish,  oval  or  rounded  bodies 
scattered  singly  throughout  the  small  intestine.  They  are  closed  vesicles 
imbedded  in  the  submucous  tissue.  In  structure,  they  consist  of  an  ex- 
terior fibrous  capsule,  containing  rounded,  nucleated  cells,  free  nuclei, 
and  granules  ;  and  fine  vessels  penetrate  into  their  interior.  Their  func- 
tion is  unknown 

The  Ag'minated  glands3  (Peyer's)  consist  of  vesicular  bodies  like 
those  just  described,  arranged  in  elliptical  patches.  Ordinarily  there  are 
from  fifteen  to  thirty  of  these  patches,  from  half  an  inch  to  two  inches 
in  length,  and  about  half  an  inch  in  breadth.  Usually  occupying  the 
ileum,  they  are  always  situated  opposite  the  attachment  of  the  mesen- 
tery, with  their  length  parallel  to  that  of  the  intestine  For  the  most 
part,  the  largest  patches  are  the  lowest  in  the  ileum,  and  in  ascending 


1  Succus  entericus. 

2  Glandulae  solitaries ;  incorrectly  Brun- 
ner's  glands ;  solitary  follicles. 

3  Peyer's  glands  ;  glandulse  Peyeri,  or 
Peyerianse ;  g.  socise  Peyeri ;  g.  agmina- 
tae  ;    g.  mucosaa    coagminatae ;    g.  muci- 
parae   racematim   congest-ae ;    g.  intesti- 


nales  plexiformes ;  g.  plexus  intestinales; 
g.  int.  spuriae  ;  g.  in  agmen  congregatse  ; 
corpuscula  glandularium  similia ;  ente- 
radenes ;  aggregate  or  aggregated  glands ; 
patches  of  Peyer;  Peyer's  plaques;  ag- 
minse  Peyeri. 


314 


THE  ALIMENTARY  APPARATUS. 


they  become  more  distant,  smaller,  and  more  circular.  When  found  in 
the  jejunum,  they  are  few  in  number,  and  small  in  size.  Upon  the  inner 
surface  of  the  intestine  the  agminated  glands  appear  depressed  below 


FIG.  228. 


PORTION  OF  THE  ILEUM,  viewed  from  without ;  the 
Berous  and  muscular  coats  removed  over  the  posi- 
tion of  an  agminated  gland.  1,  exterior  surface  of 
the  ileurn ;  2,  cut  edge  of  the  serous  and  muscular 
coats ;  3,  exterior  surface  of  the  mucous  membrane ; 
4,  an  agminated  gland ;  5,  valvulas  conniventes. 


PORTION  OF  THE  MUCOUS  MEMBRANE  FROM  THE  UP- 
PER PART  OF  THE  ILEUM,  exhibiting  very  well  the 
appearance  presented  to  the  naked  eye  when  the 
specimen  is  floated  in  water.  1,  2,  3, 4,  an  agmi- 
nated gland;  5,  valvulae  conniventes,  becoming 
much  contorted  over  the  gland;  the  short  lines 
everywhere  covering  the  surface  of  the  mucous 
membrane,  including  the  valvulae  and  the  gland, 
represent  villi ;  6,  7,  solitary  glands. 

the  general  level  of  the  mucous  membrane ;  but  they  give  rise  to  a 
slight  prominence  externally.  The  valvulae  conniventes,  in  approaching 
them,  are  usually  interrupted,  or  if  they  pass  upon  them  are  reduced  in 
size,  and  much  contorted.  Their  function  is  unknown;  and  they  are 
remarkable  for  the  changes  they  undergo  in  certain  diseases,  as,  for 
instance,  typhoid  fever. 

The  arteries  of  the  small  intestine  are  numerous,  and  are  derived  from 
the  pancreatico-duodenal,  pyloric,  and  superior  mesenteric  arteries. 
Diverging  from  the  mesentery  upon  the  intestine,  in  the  intervals  of  its 
coats  they  form  vascular  nets,  from  which  are  derived  the  three  capillary 
nets  of  the  mucous,  muscular,  and  serous  layers.  The  veins  accompany 
the  arteries.  The  lymphatics  are  numerous,  and  are  derived  from  the 
three  sources  supplied  by  the  arteries.  The  nerves  are  furnished  by 
the  solar  plexus  of  the  sympathetic  system. 


THE   ALIMENTARY  APPARATUS.  315 


THE  LAKGE  INTESTINE. 

The  Large  intestine1  is  a  cylindrical  tube,  strikingly  differing  from 
the  small  intestine  in  its  greater  capacity  and  sacculated  appearance.  It 
is  about  five  feet  in  length,  nearly  encircles  the  abdomen  in  its  course 
from  the  small  intestine  to  the  anus,  and  is  retained  in  position  by  the 
mesocolon.  Commencing  in  the  right  iliac  region,  it  ascends  in  front  of 
the  right  kidney  to  the  under  part  of  the  liver,  then  crosses  through  the 
upper  boundary  of  the  umbilical  region  to  the  left  hypochondriac  region. 
Descending  from  the  latter,  in  front  of  the  left  kidney  to  the  left  iliac 
region,  it  here  forms  an  S-like  convolution,  and  then  dipping  into  the 
pelvis,  passes  down  in  front  of  the  sacrum  to  terminate  at  the  anus.  It 
is  divisible  into  three  portions :  the  caecum,  colon,  and  rectum. 

The  Cae'cum  or  head  of  the  colon2  is  the  most  capacious  portion  of 
the  large  intestine,  and  consists  of  a  large  pouch  occupying  the  right 
iliac  region  below  the  termination  of  the  ileum.  It  is  retained  in  po- 
sition by  a  fold  of  the  peritoneum  reflected  in  front,  and  by  an  attach- 
ment of  loose  connective  tissue  to  the  iliac  fossa ;  though  sometimes  the 
peritoneum  produces  a  doubling  behind  which  renders  the  caecum  less 
fixed  than  ordinarily. 

The  cascum  is  about  two  and  a  half  inches  in  length  and  breadth,  and 
toward  its  bottom  curves  inwardly  and  backward,  and  is  abruptly  re- 
duced into  a  worm-like  prolongation,  named  the  verm'iform  appen'dix.3 
This  is  four  or  five  inches  long,  as  thick  as  a  goose-quill,  and  is  usually 
somewhat  coiled,  in  which  condition  it  is  retained  by  a  fold  of  peri- 
toneum. Its  calibre  is  narrow,  and  its  comparatively  thick  wall  has  the 
same  structure  as  other  portions  of  the  large  intestine.  It  is  viewed  as 
the  rudiment  of  the  much-elongated  caecum  of  lower  mammals. 

The  Co'lon4  is  the  second  and  longest  division  of  the  large  intestine, 
and  extends  from  the  caecum  to  the  rectum.  In  the  different  parts  of 
its  course  it  is  called  the  ascending,  transverse,  and  descending  colon, 
and  the  sigmoid  flexure,  It  is  most  capacious  at  its  commencement, 

1  Intestinum  crassum;  megalocoelia.  formis;  processus,  or  tubus  vermicula- 

2  Caecum;  caput  coli;  monocolon;  mo-  ris;  appendix  caeci;  additamentum  coli; 
nomacum;   typhloenterum :    typhloteron  -  ecphyas:  digital  appendix;  vermiform, 
monocolon;  initium  intestini  crassi ;  sac-  or  vermicular  process. 

cus  intestini  crassi,  or  coli;   prima  cella  4Colum;  intestinum  crassum  et  ple- 

coli;   initium  extuberans  coli;  the  blind  num;   i.  majus;  i.  grande;   i.  laxum;  i. 

gut-  cellulatum ;  colon  caecum ;  monenterum ; 

3  Appendix,    or    appendicula    vermi-  physce. 


316  THE  ALIMENTARY  APPARATUS. 

where  it  is  about  two  and  a  half  inches  in  diameter,  and  gradually 
diminishes  to  its  termination,  where  it  is  an  inch  less  in  breadth.  Tt 
exhibits  three  ranges  of  saccules  or  pouches,1  alternating  with  as  many 
eguidistant  longitudinal  bands2  proceeding  from  the  base  of  the  vermi- 
form appendix.  The  constrictions  between  the  saccules  appear  on  the 
interior  of  the  colon  as  crescentic  doublings3  of  its  walls. 

The  ascending  colon4  occupies  the  right  side  of  the  abdomen,  attached 
to  its  posterior  wall  by  loose  connective  tissue,  and  further  retained  in 
position  by  the  peritoneum  passing  over  the  sides  and  in  front  of  the 
intestine.  Behind,  it  is  in  relation  with  the  quadrate  lumbar  muscle  and 
kidney  ;  in  front  with  the  small  intestine. 

The  transverse  colon5  passes  obliquely  across  the  abdomen  at  the 
upper  boundary  of  the  umbilical  region.  It  is  closely  attached  to  the 
back  part  of  both  hypochondriac  regions,  and  arches  forward  toward  its 
middle,  where  it  is  loosely  suspended  by  the  transverse  mesocolon.  Above 
it  are  the  liver  and  the  stomach  ;  below,  the  small  intestine ;  and  descend- 
ing from  its  outer  border  is  the  posterior  fold  of  the  great  omentum. 

The  descending  colon6  occupies  the  left  side  of  the  abdomen,  to  the 
back  part  of  which  it  is  closely  attached  by  connective  tissue,  and  by 
the  peritoneum  passing  over  its  sides  and  front.  Its  upper  part  is  in 
contact  with  the  spleen ;  behind  it  are  the  left  kidney  and  quadrate 
lumbar  muscle  ;  and  in  front  is  the  small  intestine. 

The  sigmoid  flexure  of  the  colon7  is  an  S-like  convolution  of  the  in- 
testine attached  by  a  wide  fold  of  peritoneum  to  the  left  iliac  fossa.  It 
is  the  narrowest  and  least  sacculated  portion  of  the  colon ;  and  termi- 
nates opposite  the  left  sacro-iliac  symphysis  in  the  rectum. 

The  Il'eo-col'ic  valve.  The  ileum  opens  into  the  left  side  of  the  colon 
just  above  the  caecum,  the  orifice  being  provided  with  a  pair  of  semi- 
lunar  folds,  which  constitute  the  ileo-colic  valve.8  The  folds  are  trans- 
verse, and  project  from  the  borders  of  the  aperture  toward  each  other 
into  the  colon.  The  free  edges  of  the  folds  are  concave,  and  their  con- 
tiguous extremities  coalesce  and  are  prolonged  a  short  distance  as  a 
narrow  doubling  on  the  interior  surface  of  the  colon.  The  aperture 

1  Cellulse,  haustra,  or  loculamenta  coli.  6  Colon  descendens ;  c.  sinistrum ;  left 

2  Taeniae  Valsalvae ;  tseniae,  or  fasciae       lumbar  colon. 

ligamentosse  coli;  ligamenta  coli.  7  Flexura  sigrnoidea;  f.  S  romanum; 

3  Plicae  sigmoideae.  iliac  colon. 

4  Colon  ascendens;  c.  dextrum;  right  8  Ileo-caecal  valve;   valve  of  Bauhin, 
lumbar  colon.  of  Tulpius,  of  Fallopius,  or  of  Varolius; 

5  Colon  transversum;  transverse  arch  valvula  ilei;   v.  coli;    v.  cooci;    opercu- 
of  the  colon.  lum  ilei ;  sphincter  ilei. 


THE  ALIMENTARY  APPARATUS. 


317 


FIG.  230. 


separating  the  folds  is  elliptical;  but  when  closed,  the  free  edges  of  the 
valve  come  into  contact  so  as  to  prevent  the  return  of  matters  from  the 
large  into  the  small  intestine. 

The  third  division  of  the  large 
intestine,  the  rectum,  possesses  so 
many  peculiarities  that  its  descrip- 
tion is  reserved  for  a  special  section 
of  our  chapter. 

The  caecum  and  colon,  like  the 
small  intestine,  have  four  coats 
holding  the  same  relationship  with 
one  another. 

The  serous  coat,  derived  from 
the  peritoneum,  closely  invests  the 
colon  except  at  the  back  part  of 
the  caecum,  and  of  the  ascending 
and  descending  colon.  Along  its 
course,  it  exhibits  a  series  of  ir- 
regular, pendulous  pouches  con- 
taining fat,  and  named  the  epipr- 
loic  appendages,1 

The  muscular  coat  is  composed 
of  two  layers  of  pale-red,  unstriated 
fibres.  The  external  longitudinal 
fibres,  after  forming  a  uniform  layer 
to  the  vermiform  appendix,  are  collected  into  three  separate  bands,  which 
proceed  equidistant  from  one  another  along  the  course  of  the  caecum  and 
colon.  These  bands  are  much  shorter  than  the  intestine  would  be  if 
deprived  of  them,  and  serve  to  maintain  its  sacculated  condition.  The 
internal  muscular  fibres  are  circular,  and  form  a  continuous  layer  to  the 
caecum  and  colon,  dipping  into  the  constrictions  between  their  saccules, 
and  into  the  folds  of  the  ileo-colic  valve. 

The  fibrous  coat  is  like  that  of  the  small  intestine. 

The  mucous  membrane  is  soft,  smooth,  and  of  a  pale-pinkish  ash 
color.  It  is  without  villi  or  other  doublings  than  those  produced  by  the 
constrictions  separating  the  saccules.  Its  free  surface  everywhere  ex- 
hibits a  finely-punctured  or  sieve-like  appearance,  with  here  and  there 
small  whitish  spots.  It  is  provided  with  a  columnar  epithelium  and  two 


THE  CJECUM  LAID  OPEN,  TO  EXPOSE  THE  ILEO-C.ECAI, 

VALVE,  a,  Termination  of  the  ileum ;  6,  slit-like 
orifice  between  the  two  folds  of  the  ileo-cfecal  valve ; 
c,  caecum;  d,  vermiform  appendix;  e,  ascending 
colon. 


1  Appendices,  or  appendiculae  epiploicse,  or  pinguedinosaB ;  appendices  coli  adi- 
posse;  suplementa  epiploica;  nmbriae  carnosse;  omentula. 


318 


THE  ALIMENTARY  APPARATUS. 


FIG.  231. 


kinds  of  glands,  tubular1  and  solitary  glands,2  which  are  like  those  of 

the  small  intestine.  The  former  are  closely 
set  together  in  the  thickness  of  the  mucous 
membrane,  and  give  to  its  free  surface  the 
punctured  appearance  ;  the  latter  are  indi- 
cated by  the  scattered  whitish  spots. 

The  blood-vessels  of  the  caecum  and  colon 
are  branches  of  the  mesenteric  arteries  and 
veins.  The  lymphatics  communicate  with 

SECTION  OF  THE  MUCOUS  MEMBRANE  .  -      L 

OF  THE  COLON,  i,  free  surface  exhib-     glands  lying  in  the  course  of  the  former  ves- 
iting  the  orifices  of  the  tubular     gelg    The  nerves  are  derived  from  the  mesen- 

glands  2;   3,  fibrous  tissue;   moder- 
ately magnified.  teric  plexuses  of  the  sympathetic  system. 


THE  KECTUM. 

The  Rec'tum,3  the  terminal  portion  of  the  large  intestine,  proceeds 
from  the  sigmoid  flexure  of  the  colon,  opposite  the  left  sacro-iliac  sym- 
physis,  and  descends  along  the  middle  of  the  sacrum  and  coccyx,  to  end 
at  the  anus.  It  follows  the  curvatures  of  the  bones  just  mentioned,  and 
from  the  point  of  the  coccyx  turns  backward  and  downward.  It  is  not 
sacculated  like  the  colon,  though'  it  usually  exhibits  three  constrictions, 
corresponding  with  crescentic  folds  on  its  interior.  It  is  from  six  to 
eight  inches  long,  and  when  distended  is  club-shaped,  being  narrow  above 
and  expanded  just  before  it  contracts  to  the  anus.  In  front  of  it,  in  the 
male,  are  the  urinary  bladder,  seminal  vesicles,  and  prostate  gland ;  in 
the  female,  the  uterus  and  vagina. 

The  a'nus4  is  a  dilatable  aperture,  situated  about  an  inch  from  the  end 
of  the  coccyx.  It  is  encircled  by  a  sphincter  muscle,  covered  below  by 
thin,  dark-colored  skin,  gradually  merging  into  the  mucous  membrane  of 
the  rectum.  In  the  condition  of  rest,  this  skin  is  puckered  or  folded; 
but  in  the  act  of  defecation  the  folds  are  expanded,  and  the  mucous 
membrane  at  the  verge  of  the  anus  is  everted. 

The  upper  part  of  the  rectum  is  invested  by  the  peritoneum,  which 
attaches  it  to  the  sacrum  by  a  doubling  named  the  mes'o-rec'tum. 
Subsequently  the  peritoneum  extends  down  the  sides,  and  finally  only  on 
the  front  of  the  rectum,  and  is  thence  reflected  to  the  bladder  of  the 


1  Glands  or  follicles  of  Lieberkuhn. 

2  Solitary  follicles;  glandulae  simplices 
majores. 

3  Intestinum  rectum ;   longanon ;  ar- 
chos ;  cysaros ;  princeps ;  enthyenteron ; 
apenthysmenos. 


4  Podex  ;  archos ;  sedes  ;  culus ;  proc- 
tos;  molyne;  dactylics;  cathedra;  cyr- 
ceon ;  cysaros ;  cysthos ;  aphedra ;  he- 
dra ;  the  seat,  fundament,  or  body. 


THE   ALIMENTARY  APPARATUS.  319 

male,  or  the  vagina  and  uterus  of  the  female.  The  lower  part  of  the 
rectum  is  destitute  of  a  peritoneal  investment,  and  is  attached  to  the 
contiguous  structures  by  areolar  tissue,  usually  accompanied  with  much 
adipose  tissue. 

In  the  male,  the  portion  of  the  rectum  unprovided  with  peritoneum  is 
in  contact  in  front  with  the  base  of  the  bladder,  the  seminal  vesicles,  and 
the  prostate  gland ;  in  the  female,  it  is  in  contact  in  the  same  position 
with  the  vagina. 

The  muscular  coat  of  the  rectum  is  much  thicker  than  elsewhere  in 
the  large  intestine.  Its  external  longitudinal  fibres,  continuous  with  the 
longitudinal  bands  of  the  colon,  form  a  continuous  and  well-marked 
layer.  The  circular  fibres  likewise  form  a  continuous  layer,  and  gradu- 
ally increase  in  descending  upon  the  rectum,  and  finally  accumulate  in  a 
thick  fasciculus,  named  the  internal  sphincter  of  the  a'nus.1 

Between  the  two  sphincters  of  the  anus  the  longitudinal  muscular 
fibres  of  the  rectum  terminate,  except  a  few,  which  turn  around  the  lower 
border  of  the  internal  sphincter  and  ascend  a  short  distance  between  it 
and  the  mucous  membrane.  In  the  same  position  the  rectum  is  embraced 
from  each  side  by  the  insertion  of  the  anal  elevator  muscles. 

The  fibrous  coat  of  the  rectum  is  thicker  than  in  other  portions  of  the 
large  intestine,  and  is  strong  and  extensible. 

The  mucous  membrane  of  the  rectum  has  the  same  structure  as  that 
of  the  colon,  but  is  more  vascular,  and  becomes  bright  red  at  the  lower 
extremity.  It  exhibits  many  irregular  wrinkles,  which  are  obliterated  on 
distention  of  the  bowel.  Approaching  the  anus,  it  is  thrown  into  con- 
vergent longitudinal  folds,  named  the  columns  of  the  rec'tum,2  which 
are  often  continuous  below,  so  as  to  form  small  recesses  between  them, 
called  the  pouches  of  the  a'nus.3 

Corresponding  in  position  with  the  three  constrictions  usually  observed 
on  the  exterior  of  the  rectum,  its  mucous  membrane  is  provided  with  as 
many  wide,  crescentic  folds,  which  may  act  the  part  of  a  valvular  appa- 
ratus. 

The  arteries  of  the  rectum  are  the  haemorrhoidal  branches  of  the  infe- 
rior mesenteric,  internal  iliac,  and  internal  pudic  arteries.  The  veins  are 
numerous,  and  at  the  lower  part  of  the  rectum  form  an  intricate  net-work, 
named  the  haemorrhoi'dal  plexus,  which  returns  its  blood  through  the 
inferior  mesenteric  and  internal  iliac  veins.  Enlargement  of  the  veins 
of  the  haBmorrhoidal  plexus  at  the  verge  of  the  anus  constitute  hemor- 
rhoids or  piles.  The  lymphatics  of  the  rectum  proceed  to  the  sacral  and 

1  Musculus  sphincter  ani  interims,  or  superius. 

2  Columnae  cameos  Morgagni.  a  ginus  Morgagni;  lacunae. 


320  THE  ALIMENTARY  APPARATUS. 

lumbar  glands.  The  nerves  are  numerous,  and  are  derived  from  the 
hypogastric  plexus  of  the  sympathetic  system  and  the  contiguous  spinal 
nerves. 

The  muscles  of  the  anus  will  be  more  particularly  described  in  the 
account  of  the  perineum. 

THE  PANCREAS. 

The  Pan/creas1  is  a  long,  flat  gland,  situated  behind  the  stomach, 
opposite  the  first  lumbar  vertebra.  It  extends  from  the  descending  por- 
tion of  the  duodenum  in  the  right  hypochondriac  region,  along  the  trans- 
verse portion  of  the  duodenum  through  the  epigastric  region,  and  reaches 
the  spleen  in  the  left  hypochondriac  region.  It  closely  adheres  to  the 
duodenum,  and  is  loosely  attached  behind  by  connective  tissue  to  the 
crura  of  the  diaphragm,  aorta,  inferior  cava,  and  superior  mesenteric 
vessels.  The  latter  are  included  in  a  groove  of  the  gland,  and  some- 
times in  a  complete  canal.  In  front,  the  pancreas  is  connected  with  the 
ascending  layer  of  the  transverse  mesocolon ;  and  its  upper  border  is 
grooved  to  accommodate  the  splenic  blood-vessels. 

The  pancreas  is  pinkish  white,  and  is  less  consistent  and  of  looser 
texture  than  the  salivary  glands,  which  it  resembles  in  composition.  It 
is  from  six  to  eight  inches  long,  is  largest  at  the  right  extremity,  named 
its  head,2  and  gradually  narrows  toward  the  left  extremity,  named  its 
tail.3  Its  average  depth  is  about  one  and  a  half  inches;  its  thickness 
about  half  an  inch ;  and  it  weighs  between  two  and  three  ounces. 

The  head  of  the  pancreas  adheres  closely  to  the  inner  side  of  the  de- 
scending portion  of  the  duodenum,  and  is  frequently  partially  divided 
from  the  body  of  the  gland,  when  it  is  named  the  lesser  pan'creas.4 

In  structure  the  pancreas  is  a  racemose  gland,  and  consists  of  many 
polyhedral  lobes  and  lobules  loosely  associated  by  connective  tissue. 

The  pancreat'ic  duct5  usually  possesses  two  principal  branches,  of  which 
the  longer  and  larger  proceeds  transversely  through  the  body  of  the 
gland  from  left  to  right,  and  is  joined  near  its  termination  by  the  smaller 
branch6  derived  from  the  head  of  the  pancreas.  Upon  emerging  from  the 
pancreas,  the  duct  penetrates  the  wall  of  the  duodenum,  opening  into  it 
near  to  or  in  conjunction  with  the  common  biliary  duct,  about  four  inches 
from  the  stomach. 

1  Sweetbread;  pancratium;  pancrene;  3  Cauda. 

callicreas;     lactes;     totum    carnosum;  4  Pancreas  minus;  pancreas  of  Asseli. 

pulvinar  ventriculi ;    glandula  salivalis  5  Ductus  pancreaticus ;    d.  Wirsungi- 

abdominis.  anus ;  canal,  or  duct  of  Wirsung. 

2  Caput  pancreatis.  6  Ductus  Santorini. 


THE   ALIMENTARY  APPARATUS.  321 

The  arteries  of  the  pancreas  are  derived  from  the  pancreatico-duo- 
denal  and  splenic  arteries.  The  veins  join  the  splenic  and  superior  mes- 
enteric  veins.  Its  lymphatics  communicate  with  the  lumbar  glands,  and 
its  nerves  are  branches  from  the  solar  plexus  of  the  sympathetic  system. 

The  pancreatic  juice1  is  a  clear,  colorless,  slightly  viscid  liquid,  with 
a  distinctly  alkaline  reaction.  It  contains  a  peculiar  nitrogenized  prin- 
ciple, named  pancreatin,  and  is  an  important  emulsifying  agent  of  the 
fatty  materials  of  the  food. 

THE   LITER 

The  Liver2  is  the  largest  true  glandular  organ  of  the  body.  It  occu- 
pies the  greater  part  of  the  right  hypochondriac  region,  and  extends 
through  the  epigastric  into  a  small  portion  of  the  left  hypochon- 
driac region.  It  is  half  ovoidal  in  shape,  with  its  long  diameter  trans- 
verse, its  convex  surface  accurately  applied  to  the  diaphragm,  and  its 
nearly  flat  or  slightly  concave  surface  in  contact  with  the  stomach,  duo- 
denum, colon,  and  right  kidney.  In  front,  it  is  in  relation  with  the  ensi- 
form  and  costal  cartilages,  and  behind,  with  the  crura  of  the  diaphragm, 
aorta,  and  inferior  cava.  It  is  suspended  from  the  diaphragm  by  reflec- 
tions of  the  peritoneum  named  the  suspensory,  the  right  and  left  lat- 
eral ligaments,  and  by  a  further  attachment  of  connective  tissue  at  its 
posterior  border. 

The  right  portion  of  the  liver  is  much  larger  than  the  left,  and  is 
thicker,  more  fixed  in  position,  and  extends  lowest  in  the  abdomen  as 
well  as  highest  in  the  thorax.  The  posterior  and  right  borders  are  thick 
and  rounded ;  the  anterior  and  left  borders  are  thin  and  acute,  and  the 
most  movable  parts  of  the  organ. 

The  liver  is  of  firm,  solid  texture,  smooth  on  the  surface,  and  of  a 
reddish-brown  color.  It  often  has  more  or  less  of  a  yellowish  hue,  ap- 
parently dependent  on  the  presence  of  fat  in  the  hepatic  substance,  and 
sometimes  exhibits  superficial  livid  bluish  or  purplish  patches  and  borders. 
It  weighs  between  three  and  four  pounds,  and  measures  ten  to  twelve 
inches  from  right  to  left,  about  six  inches  from  back  to  front,  and  about 
three  inches  at  its  thickest  part.  In  the  female  it  is  usually  about  a  fifth 
less  in  weight  and  size. 

The  suspensory  ligament,  extending  from  the  median  line  of  the  dia- 
phragm to  the  upper  surface  of  the  liver,  together  with  the  longitudinal 
fissure  pursuing  the  same  direction  on  the  under  surface,  divide  the 
organ  into  two  unequal  parts,  named  the  right  and  left  lobes.  • 

1  Succus,  or  liquor  pancreaticus.  2  Hepar;  jecur;  jecinus. 

21 


322  THE  ALIMENTARY  APPARATUS. 

The  right  lobe  of  the  liver,1  four  or  five  times  the  size  of  the  left,  is 
square  in  outline,  and  is  closely  adherent  at  its  posterior  border,  by  con- 
nective tissue,  to  the  diaphragm,  between  the  widely-separated  reflections 
of  the  right  lateral  ligament.  Its  upper  surface  is  convex ;  its  lower 
surface  is  in  contact  with  the  right  kidney,  the  pyloric  extremity  of  the 
stomach,  and  the  colon.  At  the  fore  part  of  its  inferior  surface  the  gall- 
bladder reposes  in  a  fossa  ;2  and  to  the  left  and  back  of  this  it  presents 
two  small  subdivisions  named  the  quadrate  and  caudate  lobes. 

FIG.  232. 

3 


INFERIOR  SURFACE  OF  THE  LIVER.  1,  right  lobe;  2,  left  lobe;  3,  posterior  margin;  4,  anterior  margin; 
5,  quadrate  lobe;  6,  caudate  lobe;  7,  isthmus,  or  caudate  process,  connecting  the  latter  with  the  right 
lobe;  8,  9,  longitudinal  fissure;  10,  transverse  fissure;  11,  portal  vein;  12,  hepatic  artery;  13,  common 
biliary  duct  formed  by  the  union  of  the  hepatic  and  cystic  ducts;  14,  gall-bladder;  15,  inferior  cava;  16, 
hepatic  veins ;  17,  round  ligament ;  18,  anterior  part  of  the  suspensory  ligament. 

The  left  lobe  of  the  liver3  is  comparatively  thin,  trilateral  in  outline, 
and  movably  suspended  by  the  left  lateral  ligament.  Its  lower  surface 
is  in  contact  with  the  anterior  part  of  the  stomach,  and  behind,  it  is  in 
relation  with  the  cardiac  orifice  of  this  organ. 

Besides  the  suspensory  ligament  and  longitudinal  fissure,  the  right  and 
left  lobes  are  separated  at  the  anterior  and  posterior  borders  of  the  liver 
by  notches.  The  anterior  notch  is  acute,  and  continuous  below  with  the 
longitudinal  fissure ;  the  posterior  notch  is  broad  and  concave,  and  ac- 
commodates the  vertebral  column  and  the  great  blood-vessels  in  front  of 
it.  The  inferior  cava  occupies  a  deeper  portion  of  the  posterior  notch, 
excavated  in  the  right  lobe  of  the  liver ;  and  sometimes  the  hepatic  sub- 
stance extends  around  the  vein  so  as  to  inclose  it  in  a  complete  tube. 

1  Lobus  dexter;  large,  or  colic  lobe. 

2  Fossa  longitudinalis  dextra.  3  Lobus  sinister. 


THE   ALIMENTARY  APPARATUS.  323 

Above  the  posterior  notch,  the  two  layers  of  the  suspensory  ligament 
diverge1  and  become  continuous  with  the  anterior  reflections  of  the  lat- 
eral ligaments,  leaving  a  triangular  interval  at  which  the  liver  is  attached 
to  the  diaphragm  by  connective  tissue. 

The  Longitudinal  fissure2  is  a  deep  groove  on  the  under  part  of  the 
liver  extending  between  the  anterior  and  posterior  notches,  and  separat- 
ing the  right  and  left  lobes.  Its  fore  part3  is  frequently  crossed  by  a 
bridge4  of  hepatic  substance,  and  it  contains  a  fibrous  cord  named  the 
round  ligament,5  which  is  the  obliterated  umbilical  vein  of  foatal  life. 
Its  back  part6  also  contains  a  fibrous  cord,  which  is  the  obliterated  due- 
tus  venosus  of  the  foetus. 

The  Transverse  fissure7  is  a  deep  groove  passing  at  a  right  angle  from 
the  longitudinal  fissure,  between  the  quadrate  and  caudate  lobes,  to  ter- 
minate on  the  under  part  of  the  right  lobe.  This  fissure  is  the  position 
at  which  the  blood-vessels  and  nerves  enter  the  liver,  and  the  lymphatics 
and  excretory  duct  emerge. 

The  Quadrate  lobe  of  the  liver8  is  a  square  portion  of  hepatic  sub- 
stance situated  between  the  gall-bladder  on  the  right  and  the  longitudi- 
nal fissure  on  the  left,  and  extending  from  the  anterior  border  of  the 
organ  back  to  the  transverse  fissure. 

The  Caudate  lobe9  is  a  small  blunt  pyramidal  mass  of  hepatic  sub- 
stance behind  the  transverse  fissure,  extending  to  the  posterior  notch  of 
the  liver,  and  having  to  its  left  the  longitudinal  fissure,  and  to  its  right 
the  groove  for  the  inferior  cava.  A  short  isthmus  or  caudate  process10 
associates  it,  in  front  of  the  latter  vessel,  with  the  under  surface  of  the 
right  lobe. 

1  This  divergence  is  usually  and  incor-  jecoris ;  manus  hepatis,  or  jecoris ;  prin- 
rectly  described  as  if  it  were  a  distinct  cipal   fissure ;    fissure  or   fossa  of  the 
structure,  under  the  name  of  the  coro-  portal  vein ;  portal  fissure  or  fossa. 
nary  ligament ;  1.  coronarium.  a  Lobulus   quadratus ;  1.  anonymous ; 

2  Great,  or  horizontal  fissure,  furrow,  1.  accessorius  anterior  quadratus ;  ante- 
orsulcus;  fossa  umbilicalis ;  sulcus  an-  rior  portal   eminence;     auriga   anony- 
tero-posterior  jecoris;  sulcus  sinister,  or  mous. 

umbilicalis  jecoris.  9  Lobulus  Spigelii ;  the  Spigelian  lobe; 

3  Fossa  longitudinalis  sinistra.  lobulus  porticus  papillatus;  tuberculum 

4  Pons,  or  isthmus  hepatis.  papillare ;    posterior  portal  eminence ; 

5  Ligamentum  teres.  Small5  duodenal,  or  pancreatic  lobe. 

6  Fossa  ductus  venosi.  10  Lobulus  caudatus ;  lobus,  or  proces- 
'  Sulcus  transversus;  fossa  transversa;       8US  caudatus ;  tuberculum  caudatum. 

sinus  portarum ;   porta ;   p.  hepatis,  or 


324  THE  ALIMENTARY  APPARATUS. 

The  liver  derives  its  blood  from  two  different  sources,  in  this  respect 
being  quite  peculiar  among  the  organs  of  the  body.  It  is  supplied  with 
red  blood  by  a  proportionately  small  vessel,  the  hepatic  artery,  and  is 
provided  with  dark  blood  by  a  larger  vessel,  the  portal  vein,  The  two 
vessels  together  enter  the  transverse  fissure  of  the  liver,  the  artery  in 
front  of  the  vein,  and  both  divide  into  two  branches,  which  pass  to  the 
right  and  left  lobes,  and  ramify  through  them  in  a  divergent  manner  from 
below  upward,  and  toward  the  borders  of  the  organ. 

The  bile  ducts,1  originating  in  the  hepatic  substance,  converge  in  the 
course  of  the  vessels  just  mentioned,  and  emerge  into  the  transverse 
fissure  of  the  liver ;  a  branch  from  the  right  and  another  from  the  left 
lobe  conjoining  to  form  the  trunk  of  the  hepat'ic  duct. 

Numerous  lymphatics,  and  nerves  from  the  pneumogastrics  and  sym- 
pathetics,  pursue  the  same  course  as  the  above-mentioned  blood-vessels 
and  ducts,  the  whole  together  being  enveloped  by  connective  tissue.2 

The  hepatic  veins  collect  the  blood  from  the  substance  of  the  liver 
and  return  it  to  the  general  circulation.  Commencing  at  the  periphery 
of  the  organ,  they  emerge  from  before  backward,  and  terminate,  at  the 
posterior  notch  of  the  liver,  in  two  principal  trunks  which  join  the  infe- 
rior cava. 

The  relative  position  of  the  hepatic  veins  with  the  other  vessels  of  the 
liver  bears  a  resemblance  to  a  prostrate  tree  whose  boughs  and  branches 
are  entangled  among  those  of  a  clump  of  upright  trees. 

STRUCTURE  OF  THE  LIVER. 

The  liver  is  closely  invested  with  a  serous  coat  derived  from  the  peri- 
toneum, which  everywhere  covers  it  except  along  the  posterior  border, 
in  the  intervals  of  the  suspensory  and  lateral  ligaments,  and  at  the  bot- 
tom of  its  fissures.  The  subserous  connective  tissue3  is  feebly  developed, 
but  a  stronger  and  distinct  extension  of  the  same  structure  invests  those 
portions  of  the  liver  which  are  destitute  of  peritoneum.  In  the  trans- 
verse fissure  the  investing  connective  tissue  of  the  liver  is  continuous 
with  that  enveloping  the  vessels  and  ducts. 

The  material  composing  the  liver,  and  named  the  hepat'ic  substance,4 
has  a  reddish-brown  color  tinged  with  yellow,  and  has  a  finely  and  uni- 
formly mottled  aspect,  which  is  much  more  evident  in  some  of  the  infe- 

1  Biliary  ducts ;  pori  biliarii ;  ductus  biliarii. 

2  Capsule  of  Glisson ;  c.  communis  Glissoni ;  vagina  portse  ;  v.  Glissoni. 

3  Tunica  propria. 

4  Parenchyma  hepatis ;  parenchyma  of  the  liver. 


THE  ALIMENTARY  APPARATUS. 


325 


rior  animals  than  in  man,  as  for  instance  in  the  hog.  It  is  readily  torn, 
and  in  this  condition  presents  a  coarsely  granular  appearance.  The 
coarse  granules  corresponding  with  the  distinct  spots  seen  on  the  surface 
of  the  liver  are  polyhedral,  from  half  a  line  to  one  line  in  diameter,  and 
are  named  the  lob'ules  of  the  liver.1 


FIG.  233. 


FIG.  234. 


Fig.  233.  PORTION  OF  THE  LIVER  OF  THE  HOG,  exhibiting  the  lobular  structure  and  the  section  of  a  he- 
patic vein,  somewhat  magnified,  a,  Large  branch  of  the  hepatic  vein ;  the  orifices  belong  to  other 
branches;  ft,  branches  exhibiting  through  their  thin  walls  the  outlines  of  the  lobules;  the  dots  in  the 
centre  of  the  latter  are  orifices  of  the  veins  commencing  within  the  lobules. 

Fig.  234.  PORTION  OF  THE  LIVER  OF  THE  HO«,  exhibiting  the  lobular  structure.  The  large  vessel  is  a 
branch  of  the  portal  vein,  the  outlines  of  the  lobules  being  seen  through  its  transparent  wall.  The  ori- 
fices, large  and  small,  seen  in  the  portal  vein,  are  fine  branches  sent  between  the  lobules.  The  two  vessels 
lying  to  the  left  of  the  portal  vein  are  branches  of  the  hepatic  artery  and  duct. 

In  tracing  the  relation  of  the  hepatic  lobules  with  the  blood-vessels 
and  ducts  of  the  liver,  it  is  found  that  an  extreme  branch2  of  the  hepatic 
veins  commences  in  the  axis  of  every  lobule,  and  emerges  at  its  base 
to  join  a  larger  branch.3  This  arrangement  of  the  hepatic  lobules  and 
veins  resembles  the  attachment  of  leaves  by  their  midribs  and  stems  to 
the  branches  of  a  tree.  The  portal  vein,  hepatic  artery,  and  hepatic 
duct,  associated  together  by  connective  tissue,4  ramify  through  appro- 
priate canals5  of  the  hepatic  substance,  pursuing  the  same  general  course 


1  Acini. 

2  Intra-lobular  vein ;  vena  centralis. 

3  Sub-lobular  vein. 


4  Capsule  of  Glisson. 

5  Portal  canals. 


326 


THE  ALIMENTARY  APPARATUS. 


FIG.  235. 


in  relation  with  the  branches  of  the  hepatic  veins  which  has  been  indi- 
cated in  the  account  of  the  arrangement  of  their  trunks.  Finally,  the 
portal  vein,  hepatic  artery,  and  the  bile  ducts  ramify  in  the  interspaces1 
of  the  lobules,  forming  plexuses,2  and  associating  the  latter  together. 

In  the  human  liver,  these  interven- 
ing vessels  are  the  chief  connection 
of  the  lobules  with  one  another; 
but  in  some  of  the  lower  animals, 
as  for  instance  the  hog,  they  are 
accompanied  with  a  much  greater 
quantity  of  connective  tissue,  which 
renders  the  outlines  of  the  lobules 
more  defined. 

Between  the  terminal  branches3 
of  the  portal  vein  and  hepatic  ar- 
tery, occupying  the  intervals4  of 
the  lobules  and  the  commencing 
branches5  of  the  hepatic  veins  in 
the  axis  of  the  latter,  intricate  ca- 
pillary vascular  nets6  intervene. 
Thus  the  blood  which  enters  the 
liver  by  the  portal  vein  and  hepatic 
artery  pursues  its  course  until  it 
arrives  in  the  intervals  of  the  lob- 
ules, when  it  meanders  through  the 
capillary  nets  to  the  commencement 
of  the  hepatic  veins  in  the  interior  of  the  lobules. 

The  meshes  or  interspaces  of  the  capillary  vascular  nets  are  occupied 
by  the  proper  secreting  substance  of  the  liver,  constituting  the  hepatic 
cells.7  These  are  irregularly  polyhedral,  from  the  ^oo  to  tne  TZHJO  °f 
an  inch  in  diameter,  with  soft  granular  contents,  some  minute  oil  glob- 
ules, and  a  nucleus.  Generally,  two  hepatic  cells  are  about  equal  to  the 
diameter  of  the  meshes  they  occupy,  though  frequently  a  single  cell  is 
observed  extending  across  the  interval. 

From  the  description  given,  it  may  be  readily  comprehended  that  the 
hepatic  lobules  are  composed  of  capillary  vascular  nets,  intercalated 


SECTION  OF  SEVERAL  LOBULES  OF  THE  LIVER  OF  THE 
BABBIT,  the  vessels  injected,  and  the  preparation 
magnified.  The  intricate  capillary  net-works  are 
formed  from  the  portal  veins  between  the  lobules, 
and  the  hepatic  veins  within  them. 


1  Interlobular  spaces. 

2  Interlobular    veins,    arteries,    and 
ducts. 

3  Interlobular  veins  and  arteries. 


4  Interlobular  spaces. 

5  Intralobular  veins. 

6  Lobular  plexuses. 

7  Liver  cells;   hepatic  corpuscles. 


THE  ALIMENTARY  APPARATUS. 


327 


FIG.  236. 


with  hepatic  cell-nets,  as  represented  in  the  diagram,  figure  237.  So 
far,  anatomists  concur  in  their  observations  on  the  structure  of  the  liver ; 
but  in  regard  to  the  exact  relationship  of  the  hepatic  cell-nets  with  the 
bile  ducts1  there  exists  much  conflict  of  opinion.  According  to  one  view, 
the  hepatic  cell-nets  are  solid,  and  the  bile  ducts  originate  at  the  bound- 
aries of  the  lobules.  In  a  second 
view,  intercellular  passages  of  the 
hepatic  cell-nets  communicate  with 
the  commencement  of  the  bile  ducts 
in  the  interspaces  of  the  lobules. 
According  to  a  third  view,  a  third 
net,  composed  of  very  fine  tubes  of 
basement  membrane,  is  intercal- 
lated  with  the  capillary  vascular, 
and  hepatic  cell  nets,  and  joins  the 
bile  ducts  in  the  interspaces  of  the 
lobules.  Finally,  in  a  fourth  view, 
as  in  other  true  glands,  the  hepatic 

cells  are  considered  as  lining  tubes  of  basement  membrane,  from  which 
the  bile  ducts  originate  in  the  intervals  of  the  lobules. 


POLYHEDRAL  EPITHELIUM,  exemplified  by  secret- 
ing cells  of  the  liver.  The  arrangement  is  ideal. 
1,  space  occupied  by  a  blood-vessel;  2,  isolated 
cells. 


FIG.  237. 


Fig.  237.  DIAGRAM  REPRESENTING  THE  SECTION 
OF  A  LOBULE  OF  THE  LIVER,  exhibiting  the  relative 
position  of  the  hepatic  cell-nets  with  the  vascular 
nets.  1,  section  of  a  hepatic  vein  in  the  centre  of 
a  lobule ;  2,  branch  of  the  portal  vein  at  the  cir- 
cumference of  the  lobule ;  3,  capillary  net  formed 
between  the  portal  and  hepatic  veins ;  4,  branch  of 
the  hepatic  artery ;  5,  hepatic  cell-net  in  the  inte- 
rior of  the  lobule ;  6,  a  bile  duct  at  the  boundary 
of  the  latter. 

Fio.  238. 


Fig.  238.    DIAGRAM  REPRESENTING  A  TRANSVERSE 

SECTION  OF  ONE  OF  THE  CORDS  OF  THE  HEPATIC  CELL- 
NET,  showing  how  a  few  cells  may  form  a  hollow 
tube.  1,  large  cell ;  viewed  from  this  side  the  tubes 
would  appear  to  be  the  breadth  of  a  single  cell ;  2, 
two  cells  the  diameter  of  the  tube;  3,  passage-way 
for  the  bile. 


1  Interlobular  ducts  ;  pori  biliarii. 


328  THE   ALIMENTARY  APPARATUS. 


BILIARY  DUCTS  AND  GALL-BLADDER. 

The  Hepat'ic  duct,1  commencing  by  two  branches  in  the  transverse 
fissure  of  the  liver,  descends  within  the  right  border  of  the  gastro- 
hepatic  omentum,  in  advance  of  the  portal  vein  and  to  the  right  of  the 
hepatic  artery.  It  is  about  two  inches  in  length,  and  terminates,  by 
joining  with  the  cyst'ic  duct  from  the  gall-bladder,  to  form  the  common 
bil'iary  duct, 

The  Gall-bladder,2  the  receptacle  of  the  bile,  is  a  pyriform  sac,  par- 
tially lodged  in  a  fossa  on  the  under  part  anteriorly  of  the  right  lobe  of 
the  liver.  Its  fundus  or  base  projects  beyond  the  anterior  border  of  the 
latter,  in  the  vicinity  of  the  tenth  costal  cartilage ;  and  its  body  or  main 
portion  extends  in  a  backward  direction.  Its  neck  forms  an  S-like  con- 
volution, and  terminates  at  the  transverse  fissure  by  becoming  the  cyst'ic 
duct, 

The  gall-bladder  is  attached  in  its  fossa  of  the  hepatic  substance  by 
connective  tissue,  and  its  free  part,  including  the  fundus,  is  covered  by 
the  peritoneum.  Independent  of  the  latter  membrane,  its  wall  is  pro- 
vided with  a  strong  layer  of  fibrous  tissue,  and  a  thin,  diffuse  stratum  of 
pale  unstriated  muscular  fibres.  Its  lining  mucous  membrane,  stained 
yellow  from  the  bile,  is  uniformly  covered  with  fine  reticular  folds,  and 
has  a  columnar  epithelium. 

The  gall-bladder  is  supplied  with  blood, by  the  cystic  artery,  a  branch 
of  the  hepatic.  Its  veins  terminate  in  the  portal  vein. 

The  Cyst'ic  duct3  is  about  an  inch  in  length,  and  descends  to  the  left 
to  join  the  hepatic  duct  at  an  acute  angle.  Its  lining  membrane  is 
thrown  into  a  series  of  oblique  folds,  forming  a  sort  of  spiral  valve,4 
which  retards  the  flow  of  the  bile. 

The  Common  bil'iary  duct,5  formed  by  the  conjunction  of  the  hepatic 
and  cystic  ducts,  is  about  three  inches  long,  and  of  the  diameter  of  a 
large  goose-quill.  Continuing  along  the  right  border  of  the  gastro- 
hepatic  omentum,  it  pursues  its  course  behind  and  to  the  inner  side  of 
the  descending  portion  of  the  duodenum,  and  terminates  in  the  latter, 
about  four  inches  from  the  stomach.  Its  lower  portion  is  involved  in  the 
head  of  the  pancreas,  and  then  perforates  the  wall  of  the  duodenum 


1  Ductus  hepaticus.  4  Valvulus  spiralis  Heisteri. 

2  Vesicula  bills ;  v.  or  folliculus  fellis ;  5  Ductus   communis   clioledochus  ;   d. 
vesica  fellea ;  v.  biliaria ;  cystis  fellea  ;  choledochus ;  d.  hepato-cysticus ;  chole- 
cholecystis.  dochus ;  common  bile  duct. 

3  Ductus  cysticus ;  meatus  cysticus. 


THE   ALIMENTARY   APPARATUS.  329 

obliquely.     Its  orifice  is  narrowed,  and  opens  at  the  summit  of  a  slight 
papillary  eminence. 

The  common  biliary,  cystic,  and  hepatic  duct  and  its  branches  have 
the  same  structure.  They  have  a  strong  fibrous  coat,  with  a  few  unstri- 
ated  muscular  fibres,  and  a  lining  mucous  membrane.  The  latter  is  pro- 
vided with  many  minute  racemose  glands ;  and  it  has  a  columnar  epithe- 
lium, except  in  the  small  bile  ducts,  where  the  epithelium  assumes  the 
tesselated  form. 

The  secretion  of  the  liver,  named  the  bile,1  as  obtained  from  the 
human  gall-bladder,  is  a  thin,  glairy,  dark,  yellowish-brown  liquid,  of 
bitter  taste,  and  nearly  neutral  in  reaction  when  fresh.  It  is  exceed- 
ingly complex  in  chemical  composition;  and  though  an  abundant  se- 
cretion, and  a  very  constant  one  in  animals,  its  uses  have  not  yet  been 
satisfactorily  determined. 

THE  SPLEEN. 

The  Spleen2  is  a  half-ovoidal  body,  deeply  situated  in  the  left  hypo- 
chondriac region.  It  is  of  comparatively  soft  consistence,  and  of  a  livid, 
purplish  color.  Its  long  diameter  is  vertical,  with  the  larger  extremity 
upward  and  attached  to  the  diaphragm  by  a  doubling  of  peritoneum,  the 
suspensory  ligament.  Its  external  convex  surface  is  directed  toward 
the  left  side,  and  is  in  contact  with  the  diaphragm  opposite  the  three  or 
four  lower  ribs.  Its  internal  surface,  slightly  depressed  in  front  and 
behind  and  elevated  toward  the  middle,  is  directed  to  the  right  side,  and 
applied  to  the  fundus  of  the  stomach,  to  which  it  adheres  by  the  gastro- 
splenic  omentum.  Its  posterior  border  is  thick  and  rounded,  and  rests 
against  the  contiguous  kidney  and  the  diaphragm  ;  its  anterior  border  is 
thinner,  and  at  the  lower  part  usually  exhibits  one  or  two  notches  or 
clefts. 

Along  the  middle  of  the  internal  surface  of  the  spleen,  usually  indi- 
cated by  a  slight  groove  named  the  hilus,3  the  splenic  vessels  and  nerves 
pass  to  and  from  the  organ. 

The  spleen  is  very  variable  in  size,  even  in  the  condition  of  health, 
and  is  liable  to  great  changes  in  this  respect  in  certain  diseases.  Ordin- 
arily it  is  four  or  five  inches  long,  three  or  four  broad,  and  from  one  to 
one  and  a  half  thick ;  and  weighs  about  six  ounces. 

The  spleen  is  provided  with  two  coats,  of  which  the  outer  is  serous, 

1  Bills  ;  cholos ;  fel ;  the  gall. 

2  Lien  ;  splen  ;  hepar  sinistrum  ;  h.  adulterinum ;  fomes  ventriculi ;  milt. 

3  Porta  lienis. 


330  THE   ALIMENTARY  APPARATUS. 

and  the  inner  one  fibre-elastic.  The  serous  coat  derived  from  the  peri- 
toneum is  thin,  transparent,  smooth,  and  tightly  adherent  to  the  contigu- 
ous structure  beneath. 

The  fibro-elastic  coat1  is  a  moderately  strong,  extensible  layer,  com- 
posed of  interlacing  bundles  of  fibrous  tissue  mingled  with  fibres  of  elastic 
tissue.  At  the  hilus  it  becomes  continuous  with  a  similar  investment  to 
the  splenic  blood-vessels  as  they  ramify  through  the  organ. 

The  spleen  is  easily  torn ;  its  lacerated  surface  presenting  a  deep  red- 
dish-black, or  brown,  pulpy  appearance,  resembling  coagulated  blood  or 
dark  currant-jelly.  This  dark  substance,  named  the  splenic  pulp,2  may 
be  scraped  from  the  torn  surface,  or  it  may  be  removed  from  portions  of 
the  spleen  by  maceration  or  repeated  washings,  leaving  a  spongy  mass, 
composed  of  the  splenic  blood-vessels,  associated  with  numerous  bundles 
of  fibro-elastic  tissue.  These  bundles,  named  trabec'ulae,  spring  from 
the  interior  surface  of  the  fibro-elastic  coat  of  the  spleen,  and  form  an 
intricate  net- work  or  sponge-like  arrangement  which  supports  the  splenic 
blood-vessels  and  contains  within  its  meshes  the  splenic  pulp. 

The  pulp  of  the  spleen,  examined  with  the  microscope,  is  found  to 
consist  of  the  following  elements :  1,  numerous  blood-corpuscles,  for 
the  most  part  unchanged,  but  many  apparently  exhibiting  various  condi- 
tions of  disintegration ;  2,  finely  granular  matter,  partly  colorless,  but 
mostly  of  various  shades  of  red  passing  into  brown  ;  3,  numerous  iso- 
lated nuclear  bodies  ;  4,  colorless  nucleated  cells ;  5,  a  few  cells  contain- 
ing blood-corpuscles  apparently  in  a  state  of  disintegration ;  and  6, 
occasionally  red  acicular  crystals,  derived  from  the  decomposition  of 
blood-corpuscles. 

The  arrangement  of  these  different  elements  of  the  splenic  pulp,  in 
their  relationship  with  one  another  and  with  the  blood-vessels,  has  not 
yet  been  determined  in  a  satisfactory  manner. 

Adhering  to  the  sides  of  the  smallest  arteries  of  the  spleen,  and  im- 
bedded in  the  pulp,  there  exist  certain  small,  rounded,  whitish  bodies, 
named  splenic  corpuscles.3  These  are  variable  in  number  and  size, 
usually  measure  about  one-sixth  of  a  line  in  diameter,  and  resemble,  in 
composition,  the  solitary  glands  of  the  intestines. 

In  proportion  to  its  size,  the  spleen  is  the  most  vascular  organ  of  the 
body.  The  splenic  artery  divides  into  a  half  dozen  or  more  branches, 
which  diverge  along  the  hilus  and  enter  the  spleen.  Spreading  through 
the  organ  in  numerous  ramifications,  those  of  the  different  principal 
branches,  not  anastomosing,  they  finally  break  up  into  a  multitude  of 


1  Tunica  propria ;  t.  albuginea.  2  Pulpa  lienis. 

3  Corpuscles  of  Malphighi ;  Malphighian  bodies. 


THE   ALIMENTARY  APPARATUS.  331 

pencil-like  bundles  of  delicate  vessels,  which  terminate  in  the  capillaries 
of  the  splenic  pulp.  The  veins  return  in  the  course  of  the  arteries,  with 
which  they  correspond  in  number,  but  are  larger.  The  lymphatics  are 
few  in  comparison  with  those  of  the  other  abdominal  viscera.  The 
nerves  are  derived  from  the  solar  plexus  of  the  sympathetic  system. 

The  function  of  the  spleen,  though  the  subject  of  numerous  and 
laborious  investigations,  yet  remains  unknown.  It  has  been  supposed 
that  the  spleen  acts  as  a  reservoir  or  diverticulum  to  the  blood  during 
the  state  of  rest  of  the  digestive  organs,  and  during  those  conditions 
in  which  the  blood  retires  from  the  surface  toward  the  interior  of  the 
body.  It  has  also  been  looked  upon  as  being  the  position  in  which  the 
blood-corpuscles,  after  having  fulfilled  their  function  in  the  economy, 
undergo  dissolution,  yielding  their  chemical  elements  to  the  circulating 
liquor  sanguinis.  Further,  it  has  been  supposed  to  be  the  organ  in 
which  the  blood-corpuscles  have  their  origin. 


CHAPTER    YIL 

THE     VASCULAE     SYSTEM. 

THE  Vas'cular  system  consists  of  the  heart,  blood-vessels,  lymphatics, 
and  their  contained  liquids,  the  blood  and  lymph.  The  heart  is  a  power- 
ful muscular  organ,  and  is  the  chief  agent  in  the  circulation  of  the  blood. 
The  blood-vessels  consist  of  branching  tubes,  named  arteries  and  veins, 
and  an  intermediate  set  of  tubes,  called  capillaries.  The  lymphatics 
consist  of  vessels  and  peculiar  bodies,  named  lymphatic  glands. 

GENERAL  CHARACTERS  OF  THE  ARTERIES. 

The  Ar'teries1  are  cylindrical,  membranous  tubes,  which  commence  in 
two  great  trunks,  the  aorta  and  pulmonary  artery.  They  undergo  divi- 
sion as  in  the  branching  of  a  tree,  and  distribute  the  blood  throughout 
the  body,  terminating  in  the  capillaries.  Their  branches  mostly  come 
off  at  acute  angles,  are  commonly  of  uniform  diameter  in  each  case,  but 
successively  diminish  after  and  in  consequence  of  division ;  and  in  this 
manner  gradually  merge  into  the  capillary  system.  As  a  general  rule, 
the  combined  area  of  the  branches  is  greater  than  that  of  the  vessel 
from  which  they  emanate,  and  hence  the  collective  capacity  of  the  arterial 
system  increases  with  its  distribution.  This  arrangement  facilitates  the 
circulation ;  for  the  increasing  capacity  of  the  vessels  in  their  course 
compensates  for  the  retarding  influence  of  friction. 

Arteries  have  comparatively  thick  walls,  and  even  when  emptied,  as 
is  usually  the  case  after  death,  they  for  the  most  part  maintain  their  open 
calibre.  Generally  they  pursue  a  straight  course,  but  are  often  curved,  and 
are  sometimes  tortuous,  especially  in  positions  liable  to  frequent  change 
of  volume,  or  of  expansion  and  contraction ;  as  in  the  lips,  the  urinary 
bladder,  the  uterus,  etc.  The  larger  arteries  are  generally  deeply  situ- 
ated, and  frequently  pursue  their  course  along  the  bones,  where  they  are 
protected  from  undue  extension.  In  the  limbs  they  occupy  the  sides  of 

1  Sing. :  arteria ;  pi. :  arterije. 
(332) 


THE  VASCULAR  SYSTEM. 


333 


flexion,  where  they  are  less  exposed  to  a  variety  of  accidents  than  if 
situated  on  the  sides  of  extension. 

Arteries,  in  their  course  of  distribution,  form  intercommunications, 
named  anastomo'ses,1  which  become  more  frequent  as  the  vessels 
diminish  in  size.  Even  in  many  large  vessels  anastomoses  are  numerous, 
where  it  is  important  that  the  blood  should  be  incessantly  supplied  to 
organs,  as  in  the  case  of  the  arteries  of  the  brain ;  or  where  the  vessels 
are  constantly  exposed  to  the  liability  of  pressure,  as  in  the  arteries  of 
the  hand  and  foot,  those  around  the  joints,  and  those  of  the  abdominal 
viscera. 

The  arteries  are  highly  elastic,  being  extensible  and  retractile  both  in 
length  and  breadth.  During  life,  from  their  being  provided  with  mus- 
cular tissue,  they  are  also  contractile. 

The  walls  of  the  arteries  are  composed  of  three  coats,  which  vary  in 
vessels  of  different  sizes. 

FIG.  239. 


TRANSVERSE  SECTION  OF  THE  VTALLS  OF  THE  AORTA,  treated  with  acetic  acid,  and  magnified.  1,  internal 
coat :  a,  epithelium  and  basement  membrane ;  b,  c,  layers  of  elastic  tissue.  2,  middle  coat :  d,  layers  of 
elastic  tissue ;  e,  muscular  and  connective  tissue.  3,  external  coat,  composed  of  fibrous  tissue  and  fine 
nets  of  elastic  tissue. 

The  external  coat2  is  comparatively  thin  in  the  largest  arterial 
trunks ;  increases  to  half  the  thickness  of  the  walls  in  the  medium-sized 
arteries ;  becomes  relatively  thicker  in  the  smaller  branches ;  but  finally 
disappears  in  those  which  merge  into  the  capillaries.  It  is  mainly  com- 
posed of  fibrous  tissue,  the  bundles  and  filaments  of  which  pursue  a 
spiral  direction,  crossing  one  another  from  opposite  sides  of  the  vessel. 
Its  exterior  portion  is  of  looser  texture,  and  adheres  to  the  surrounding 
parts ;  its  interior  portion  is  intimately  blended  with  the  middle  coat. 
It  contains  fine  nets  of  elastic  tissue,  which  are  most  abundant  toward 
the  interior.  To  this  coat  the  arteries  chiefly  owe  their  tenacity. 


1  Interosculations ;  inosculations ;  reuniones  vasorum ;  exanastomoses  ;  concursi. 

2  Tunica  adventitia ;  t.  externa ;  t.  cellularis  ;  vagina  cellularis. 


334 


THE   VASCULAR   SYSTEM. 


The  middle  coat1  forms  the  principal  thickness  of  the  walls  of  the 
largest  arterial  trunks,  gradually  diminishes  in  their  branches,  and  finally 
disappears.  In  the  largest  arteries  it  is  of  a  yellowish  color,  and  is 
mainly  composed  of  elastic  tissue,  with  a  small  proportion  of  unstriated 
muscular  tissue  and  some  connective  tissue.  In  the  medium-sized  and 
smaller  arteries  it  is  of  a  reddish  hue,  and  chiefly  consists  of  muscular 
tissue,  with  a  small  proportion  of  elastic  and  connective  tissue.  In  the 
smallest  arteries  the  middle  coat  consists  alone  of  muscular  tissue. 


FIG.  240. 


FIG.  241. 


i 


ELASTIC  TISSUE  FROM  THE  MIDDLE  COAT  OF  THE 
POPLITEAL  ARTERY,  highly  magnified.  The  dark 
reticnlar  lines  indicate  a  narrow  net  of  elastic  tis- 
sue ;  the  other  part  of  the  figure  represents  a  layer 
of  perforated  membrane,  which  is  a  variety  of  the 
same  tissue. 


UNSTRIATED  MUSCULAR  FIBRES  FROM  THE  MIDDLE 
COAT  OF  THE  ARTERIES,  highly  magnified.  1,  from 
the  popliteal  artery :  a,  without,  and  6,  treated  with 
acetic  acid ;  2,  from  a  branch  of  the  anterior  tibial 
artery  :  a,  pointing  to  the  centre  in  all  the  figures, 
indicates  the  nucleus. 


The  elastic  and  muscular  tissues  are  arranged  in  layers  varying  in 
number  according  to  the  thickness  of  the  coat,  and  their  fibres  pursue  a 
circular  course  around  the  vessels.  The  muscular  fibres  are  fusiform, 
with  elongated  oval  nuclei.  The  elastic  tissue  exhibits  all  varieties  of 
form,  from  fine  nets  to  broad-banded  ones,  constituting  the  so-called 
perforated  or  fenes'trated  membranes, 

To  the  middle  coat  arteries  owe  their  contractility,  most  of  their 
elasticity,  and  much  of  their  strength ;  though  it  is  of  such  a  brittle 
character  that  the  application  of  a  ligature  cuts  or  breaks  it  through. 

The  internal  coat2  of  the  arteries  is  the  thinnest,  most  transparent, 
and  elastic.  It  is  composed  of  a  lining  epithelium,  a  basement  membrane, 


T.  media ;  t.  elastlca. 


2  Tunica  intima ;  t.  glabra ;  endangium. 


THE  VASCULAR  SYSTEM.  335 

and  layers  of  elastic  tissue.  The  epithelium  consists  of  a  single  layer 
of  elongated,  lozenze-shaped  cells,  which  are  narrowest  in  the  smallest 
arteries.  The  basement  membrane  is  homogeneous  and  elastic,  and  is 
the  last  structure  of  the  arteries  becoming  continuous  with  the  capillaries. 
The  elastic  tissue  consists  of  fibres,  nets,  and  the  so-called  perforated 
membranes,  pursuing  a  longitudinal  direction,  and  intimately  associated 
with  the  middle  coat. 

The  larger  arteries  have  their  walls  furnished  with  nutrient  vessels, 
which  are  derived  from  small  neighboring  arteries,  and  not  from  the 
trunks  they  supply.  The  nutrient  vessels  form  a  net-work  of  capillaries, 
from  which  veins  arise  to  empty  into  the  contiguous  larger  venous 
branches.  The  arteries  are  accompanied  by  many  nerves,  chiefly  from 
the  sympathetic  system,  but  to  what  extent  their  walls  are  supplied  by 
them  has  not  been  satisfactorily  determined. 

The  elasticity  of  the  arteries  allows  them  to  dilate  as  each  impulse  of 
the  heart  sends  an  additional  supply  of  blood  to  their  circulating  current. 
The  dilatation  moves  rapidly  onward  in  a  wave-like  manner,  and  insen- 
sibly decreases  until  it  is  entirely  lost  in  the  smallest  arteries.  It  is 
followed  by  contraction  of  the  arterial  walls  upon  their  contents,  both 
in  consequence  of  their  elasticity  and  the  excitation  of  their  muscular 
structure.  The  alternation  of  dilatation  and  contraction  of  the  arteries 
constitutes  pulsation  or  the  pulse.1 

GENERAL  CHARACTER  OF  THE  VEINS. 

The  Veins2  are  branching  tubes  like  the  arteries,  but  are  generally 
larger,  more  numerous,  and  consequently  more  capacious.  They  com- 
mence in  the  capillary  vessels,  gradually  converge  in  a  reverse  course 
mostly  along  side  of  the  arteries,  and,  with  one  exception,  terminate  in 
the  heart  by  seven  trunks.  Four  of  the  latter  are  the  pulmonary  veins ; 
the  two  largest  ones  are  the  superior  and  inferior  cava,  and  the  smallest 
is  the  coronary  vein,  derived  from  the  walls  of  the  heart  itself.  The  ex- 
ception is  the  portal  vein,  which  derives  its  branches  from  the  bowels, 
and  is  distributed  through  the  liver. 

The  larger  veins  consist  of  a  superficial  and  deep  series;  the  former 
unassociated  with  arteries,  and  running  immediately  beneath  the  skin, 
the  latter  usually  accompanying  the  arteries,  and  thence  named  com- 
panion veins.3  The  arterial  trunks  and  their  large  branches  generally 


1  Pulsus  ;  pulsatio ;  ictus,  or  incursus  arteriarum. 

2  Sing. :  vena ;  pi. :  venae  ;  phlebs. 

3  Venae  satellites ;  v.  comites ;  v.  concomites. 


336 


THE   VASCULAR  SYSTEM. 


have  one  companion  vein ;  but  the  medium-sized  and  smaller  arteries 
usually  possess  a  pair,  arranged  one  on  each  side  of  the  artery. 

Anastomoses  between  veins  of  comparatively  large  size  are  much 
more  frequent  than  among  corresponding  arteries  ;  and  in  some  positions 
they  form  coarse,  intricate  nets,  named  venous  plexuses, 

The  veins  have  much  thinner,  but  relatively  stronger,  walls  than  the 
arteries,  and,  after  death,  according  to  the  quantity  of  their  remaining 
contents,  are  found  collapsed.  Many  of  the  larger  ones  are  provided 

with  valves,  which  are  so  arranged 
as  to  prevent  the  reflux  of  blood. 
The  valves  are  usually  in  pairs, 
opposite  each  other,  and  consist  of 
crescentic  doublings  of  the  lining 
membrane  of  the  veins,  strength- 
ened with  some  intervening  fibro- 
elastic  tissue.  The  convex  border 
of  the  valves  is  attached  ;  the  con- 
cave border  is  free,  and  directed 
from  the  periphery  of  the  body 
toward  the  heart.  Behind  each 
valve  the  vein  is  dilated  into  a 
pouch  or  sinus,  which  prevents  the 
adherence  of  the  valve  to  the  side 
of  the  vein  when  the  blood  pursues 
its  proper  course.  If  the  vein  is 
compressed,  the  blood  driven  back  enters  the  sinus  and  presses  the  valve 
inward,  so  as  to  meet  the  opposite  one  in  the  middle  of  the  channel,  and 
thus  close  it. 

The  pulmonary  veins  throughout  possess  no  valves,  and  this  also  is  the 
case  with  the  superior  and  inferior  cava,  the  portal  vein  and  its  branches, 
the  hepatic,  renal,  uterine,  and  spinal  veins,  and  most  of  those  of  the 
head  and  neck.  They  are  more  abundant  in  the  veins  of  the  lower  than 
in  those  of  the  upper  extremities. 

In  certain  membranes  and  some  other  organs,  channels  exist  lined  with 
an  extension  of  the  internal  coat  of  the  blood-vessels,  and  serving  the 
function  of  veins.  These  channels  are  usually  termed  venous  sinuses, 
as  the  sinuses  of  the  dura  mater,  those  of  the  bones,  and  of  the  uterus. 

The  walls  of  the  veins,  as  in  the  arteries,  are  composed  of  three  coats, 
having  the  same  general  character. 

The  external  coat  is  the  thickest,  and  gradually  increases  in  this 
respect  from  the  smallest  to  the  largest  veins.  As  in  the  arteries,  it  con- 
sists of  fibrous  tissue,  with  longitudinal  nets  of  elastic  tissue.  In  the 


DIAGRAMS  EXHIBITING  THE  ARRANGEMENT  OF  THE 
VALVES  OF  VEINS.  A,  vein  laid  open,  showing  the 
valves  in  pairs  ;  B,  longitudinal  section  of  a  vein, 
indicating  the  mode  in  which  the  valves,  by  appo- 
sition of  their  free  edges,  close  its  calibre.  The  di- 
lated condition  of  the  walls  behind  the  valves  is 
also  seen.  C,  vein  distended,  showing  how  the 
sinuses  behind  the  valves  become  dilated. 


THE   VASCULAR   SYSTEM.  337 

larger  veins  of  the  abdominal  cavity  it  is  also  provided  with  tmstriated 
muscular  tissue,  the  lamina  of  which  pursue  a  longitudinal  direction. 

The  middle  coat  is  best  developed  in  the  medium-sized  veins,  and  dis- 
appears altogether  in  the  smallest  ones.  As  in  the  arteries,  it  consists 
of  unstriated  muscular,  elastic,  and  connective  tissue,  the  elements  of 
which  usually  pursue  a  circular  direction,  though  laminae  of  the  elastic 
tissue  also  have  a  longitudinal  direction.  In  the  largest  veins  the  middle 
coat  contains  a  large  proportion  of  connective  tissue,  and  is  sparingly 
provided  with  muscular  tissue. 

The  internal  coat,  like  that  of  the  arteries,  consists  of  a  lining  epithe- 
lium, an  elastic  basement  membrane,  and  longitudinal  laminae  of  elastic 
tissue,  which,  however,  do  not  form  fenestrated  membranes. 

The  walls  of  the  veins  are  furnished  with  nutritive  vessels.  A  few 
nerves  have  been  traced  only  in  the  larger  veins.  Both  arteries  and 
veins  are  insensible  to  painful  impressions  in  a  condition  of  health.  The 
acute  pain  often  evinced  in  the  ligation  of  an  artery  is  due  to  the  inclu- 
sion of  accompanying  nerves. 


THE  CAPILLARIES. 

The  Capillaries1  are  minute  blood-vessels  usually  arranged  in  the 
form  of  nets  among  the  proper  tissue  elements  of  the  organs  of  the 
body.  They  communicate  with  the  termination  of  the  arteries  and  the 
commencement  of  the  veins,  but  are  otherwise  closed,  or  never  commu- 
nicate by  open  orifices  with  the  structures  in  which  they  are  distributed. 
The  proper  tissue  elements  are  in  all  cases  exterior  to  the  capillary  ves- 
sels, or  occupy  the  meshes  of  the  capillary  nets ;  and  they  obtain  their 
nutritive  material  simply  by  imbibition  through  the  walls  of  the  capil- 
laries. 

In  any  special  structure  the  capillaries  are  remarkable  for  the  general 
uniformity  of  their  size,  but  in  the  different  structures  of  the  body  they 
range  from  the  ^Jy  to  the  yj^  of  a  line  in  diameter.  The  smallest  ad- 
mit the  passage  of  blood  corpuscles,  though  but  a  short  time  has  elapsed 
since  the  opinion  universally  prevailed  that  in  all  structures  of  the  body 
capillaries2  existed  which  only  transmitted  the  liquor  sanguinis. 

In  structure  the  capillaries  consist  of  tubes  of  transparent,  elastic, 
structureless  membrane  with  scattered  oval  nuclei.  There  is  no  lining 
epithelium,  but  only  the  single  layer  of  membrane  just  described,  which 

1  Vasa  capillaria ;  micrangia ;  trichangia.  2  Vasa  serosa. 

22 


338 


THE   VASCULAR   SYSTEM. 


FIG.  243. 


is  continuous  with  the  basement  layer  of  the  internal  coat  of  the  arteries 

and  veins. 

The  form  of  the  capillary  nets  is  in  a  measure  dependent  upon  the  ar- 
rangement of  the  proper 
elements  of  the  tissues 
they  supply.  Thus,  in  the 
lungs,  the  nets  accommo- 
date themselves  to  the 
form  of  the  air-cells ;  in 
the  muscles,  they  have 
elongated  meshes,  most 
of  the  vessels  pursuing 
the  course  of  the  muscu- 
lar fibres,  and  being  con- 
nected by  short  ones 
crossing  the  latter,  etc. 

In  many  instances,  es- 
pecially within  papillary 
eminences,  the  capillaries 
form  loops,  as  in  the  pa- 
pillae of  taste  and  of  touch. 
The  greater  the  vital 
activity  of  an  organ,  the 
more  dense  or  close  is  the 
capillary  net ;  or,  in  other 

A  SMALL  ARTERY  gradually  passing  into  the  structure  of  the  ca-  words     the    greater    is    its 

pillary  vessels.  1,  artery  with  transverse  muscular  fibres :  a,  struc-  ,  _         '  . 

tureless  membrane ;  6,  nuclei  of  transverse  muscular  fibres ;  c,  nu-  degree  01  VaSCUlanty.    1  he 

clei  of  structureless  membrane;  2,  3,  4,  capillaries  composed  of  capillary  net  Or  pleXUS  is 
structureless  membrane  (a)  with  scattered  nuclei  (d).  -,  ,  .  , ,  1  . , 

closest  in  the  lungs,  the 

glands,  especially  the  liver  and  kidneys,  the  skin  and  mucous  membranes, 
the  muscles,  and  the  gray  nerve  substance.  In  the  fibrous  tissues  and 
the  bones  the  nets  have  wide  meshes,  and,  of  course,  comparatively  few 
vessels. 

THE  BLOOD. 

The  Blood1  constitutes  the  circulating  contents  of  the  heart,  arteries, 
capillaries,  and  veins.  It  is  a  highly  complex  liquid,  furnishing  nutritive 
material  to  all  the  tissues  of  the  body.  It  is  somewhat  viscid,  and 
heavier  than  water — its  specific  gravity  being  about  1055.  When  fresh, 
it  appears  to  the  naked  eye  perfectly  homogeneous,  and  of  a  more  or 


Sanguis ;  cruor ;  haema ;  lapis  animalis. 


THE   VASCULAR  SYSTEM. 


339 


FIG.  244. 


less  deep-red  hue.  It  has  an  alkaline  reaction,  a  saline  taste,  and  a 
feeble  peculiar  odor.  Its  color  varies  in  different  vessels,  and  according 
to  its  degree  of  accumulation.  A  thin  stratum  always  appears  light 
red,  and  the  color  is  deepened  by  an  increase  in  the  thickness  of  the 
stratum.  In  the  pulmonary  veins,  the  renal  veins,  the  aorta  and  its 
branches,  it  appears  bright  red ;  in  the  superior  and  inferior  cavae  and 
their  branches  generally,  in  the  portal  veins  and  the  pulmonary  arteries, 
it  resembles  in  color  the  pulp  of  the  black-heart  cherry,  or  is  of  a  deep- 
maroon  hue. 

The  amount  of  blood  in  the  adult  varies  with  the  bulk  and  organic 
activity  of  the  individual,  but  may  be  stated  to  be  about  equal  in  weight 
to  one-tenth  of  the  body. 

When  the  blood  is  examined  by  means  of  the  microscope,  spread  in 
a  thin  layer  on  a  plate  of  glass,  or 
while  circulating  in  the  capillaries, 
it  is  observed  to  consist  of  a  color- 
less liquid,  named  the  liquor  sang'- 
uinis,  and  a  multitude  of  minute 
circular  bodies  called  blood  cor'- 
puseles.1  These  are  of  two  kinds, 
red  and  colorless  corpuscles,  of 
which  the  former  very  greatly  pre- 
dominate and  give  to  the  blood  its 
color. 

The  red  blood  cor'puscles2  are  so 
exceedingly  small  and  numerous 
that  a  single  drop  of  blood  a 
couple  of  lines  in  diameter  con- 
tains about  100,000,000  of  them.  They  are  biconcave  disks  with  rounded 
borders,  resembling  in  shape  the  familiar  article  of  food  commonly  known 
as  the  water  cracker.  They  vary  in  diameter,  but  average  about  the 
3  J3  of  a  line  in  breadth,  with  about  a  fourth  of  that  thickness.  They 
are  elastic,  and  appear  homogeneous,  presenting  no  trace  of  gran- 
ular contents  or  nucleus.  Isolated,  they  appear  of  a  yellowish  hue,  and 
it  is  only  by  their  accumulation  that  they  give  rise  to  the  decided  red 
color  of  the  blood. 

Through  evaporation  of  the  containing  liquid,  as  exposed  upon  the 
slip  of  glass  on  which  the  blood  corpuscles  are  observed,  they  assume  a 

1  Blood  globules,  or  vesicles;  globuli,  vesiculse,  sphaerulae,  corpuscula,  folliculi, 
cellulge,  particulae,  or  granula  sanguinis. 

2  Blood  disks 


RED  BLOOD  CORPUSCLES,  highly  magnified.  1,  cor 
puscles  seen  on  their  broad  surface;  2,  seen  on  their 
edge ;  3,  rolls  of  corpuscles,  indicating  the  manner 
in  which  they  are  frequently  observed  to  arrange 
themselves.  The  remaining  figures  more  highly 
magnified :  4,  corpuscle  seen  on  its  broad  surface ; 
5,  seen  on  its  edge ;  6,  a  series  of  corpuscles ;  7,  a 
corpuscle  in  section,  indicating  its  biconcave  dis- 
coidal  form. 


340  THE   VASCULAR   SYSTEM. 

tuberculated  and  irregular  stellated  appearance.  In  water  they  swell  up, 
become  paler  and  spherical,  and  finally  burst,  exuding  a  faintly-colored 
liquid,  and  leaving  a  structureless  membrane  of  extreme  tenuity  behind. 
When  viewed  in  any  quantity  on  a  glass  slide  beneath  the  microscope, 
the  blood  corpuscles  are  frequently  observed  with  a  disposition  to  ar- 
range themselves  into  piles  or  columns,  a  tendency  which  becomes  more 
marked  in  the  blood  of  inflammation. 

The  size,  form,  and  constitution  of  the  red  blood  corpuscles  vary  in 
different  animals.  In  all  mammals  except  the  camel  tribe,  they  are  cir- 
cular, and  have  the  same  constitution  as  in  man,  but  are  generally  smaller. 
In  the  elephant  they  are  larger,  though  there  is  no  general  relationship 
between  the  size  of  the  corpuscles  and  that  of  the  animal ;  thus,  they 
are  larger  in  the  rat  than  in  the  horse,  and  are  smallest  in  the  musk 
deer.  In  the  camel  tribe,  birds,  reptiles,  and  fishes,  they  are  elliptical, 
and  are  provided  with  a  nucleus.  In  the  batrachian  reptiles  they  are 
larger  than  in  any  other  animals ;  thus,  in  frogs  they  measure  the  ^  of  a 
line  long ;  in  salamanders,  -£$ ;  and  in  the  proteus,  ^  of  a  line. 

The  colorless  blood  corpuscles1  are  comparatively  few  in  number — not 
more  than  one  to  several  hundred  of  the  red  corpuscles.  They  are 
larger  than  the  latter,  and  measure  about  the  2 ?^  of  a  line  in  diameter, 
are  spherical,  and  have  faintly  granular  contents  and  a  nucleus. 

Most  of  the  colorless  corpuscles  are  derived  from  the  lymph,  which,  as 
will  hereafter  be  seen,  pours  into  the  blood-vessels ;  but  some  of  them  also 
appear  to  originate  in  the  spleen.  According  to  the  observations  of 
T.  W.  Jones,  their  nuclei  finally  become  red  blood  corpuscles. 

The  liquor  sang'uinis,2  or  blood  liquor,  is  a  pale,  amber-colored  liquid 
which  holds  the  blood  corpuscles  in  suspension.  It  is  remarkable  for 
its  tendency  to  coagulate  or  assume  the  solid  condition  upon  removal 
from  the  circulating  current,  which  change  depends  on  its  holding  fibrin 
in  solution.  It  is  highly  important  as  being  the  nutritive  liquid  which 
is  imbibed  from  the  capillaries  by  all  the  tissues  of  the  body. 

When  blood  is  removed  from  the  circulation  it  ordinarily  coagulates 
or  solidifies  in  a  few  moments.  The  coag'ulum  or  clot3  then  slowly  con- 
tracts, and  expresses  from  the  mass  a  clear  amber-colored  liquid,  called 
the  serum,  in  which  the  remainder  of  the  clot  floats. 

The  se'rum4  is  the  liquor  sanguinis  deprived  of  its  fibrin,  which  in 


1  White  globules  ;  leucocytes  ;  lymph  3  Crassamentum ;      c  r  u  o  r ;      insula ; 
corpuscles.  thrombus;   placenta  sanguinis,  or  cru- 

2  Plasma ;  coagulable  lymph ;  plastic  oris ;  hepar  sanguinis. 
lymph  ;    hsematoplasma ;   mucago  ;   mu-  4  Ichor  sanguinis ;  haemydor. 
cilage ;  intercellular  fluid. 


THE  VASCULAR  SYSTEM.  341 

coagulation  entangles  the  blood  corpuscles  and  thus  forms  the  clot.  The 
relation  of  the  different  constituents  of  liquid  and  coagulated  blood  may 
be  understood  by  reference  to  the  following  plan  : — 

{Corpuscles \  pint  ) 

Liquor  sanguinis...  {™™  _;;;;;;;;  £  '•  j  Coagulated  blood. 

The  coagulated  fibrin  of  the  blood,  examined  with  the  microscope,  ex- 
hibits a  fibrillated  appearance,  thus  apparently  indicating  that  the  ready 
coagulation  of  this  material  is  a  step  toward  organization,  or  the  pro- 
duction of  definite  form  in  a  living  body. 

The  blood  of  the  hepatic  veins,  and  that  which  escapes  from  the  torn 
vessels  of  the  uterine  mucous  membrane  during  the  menstrual  period, 
ordinarily  does  not  coagulate,  thus  indicating  the  absence  of  fibrin. 

The  composition  of  the  blood  varies  in  the  quantity  of  its  chemical 
ingredients  not  only  in  different  sexes,  ages,  individuals,  and  conditions 
of  health,  but  also  in  different  parts  of  the  body. 

A  thousand  parts  of  blood  by  evaporation  are  found  to  contain  on 
an  average  about  790  parts  of  water  and  210  parts  of  solid  materials. 
The  same  quantity  of  blood  consists  of  about  513  parts  of  blood  cor- 
puscles and  41*7  parts  of  liquor  sanguinis.  The  chemical  constituents 
of  these,  according  to  recent  analyses,  appear  to  be  as  follows : — 


513  parts  of  blood  corpuscles 
contain : 


f  Water 350 

Globulin  with  Iron 151 

Haematin  with  Iron 8 

Chloride  of  potassium ;  phosphates  of  potasssa, 


soda,  lime,  and  magnesia ;    soda,  and  sul- 
phate of  potassa 4 

f  Water 440 

Albumen 40 

487  parts  of  liquor  sanguinis  J  Fibrin , 3 

contain  :  I  Chloride  of  sodium  and  potassium ;  phosphates 

of  soda,  lime,  and  magnesia ;  soda,  and  sul- 
phate of  potassa 4 

THE  HEART. 

The  Heart,1  the  great  central  power  of  the  circulation  of  the  blood, 
is  situated  within  the  cavity  of  the  thorax,  inclosed  by  a  fibro-serous 
sac,  the  pericardium.  It  lies  between  the  lungs,  resting  upon  the  dia- 
phragm, and  encroaches  more  on  the  left  than  on  the  right  side.  Its 
shape  is  conical,  and  its  position  oblique.  It  is  everywhere  free  or  un- 

1  Cor ;  cardia. 


342  THE  VASCULAR  SYSTEM. 

attached  except  at  the  base,  by  which  it  is  suspended,  through  means  of 
the  blood-vessels  emanating  therefrom,  to  the  front  of  the  vertebral 
column. 

FIG.  245  FIG.  246. 


Fig.  245.  FRONT  VIEW  OF  THE  HEART,  a,  base  of  the  ventricles;  b,  apex;  c,  auricular  appendage  of  the 
right  auricle;  d,  superior  cava;  e,  longitudinal  groove  separating  the  ventricles;  /,  aorta;  k, pulmonary 
artery;  I,  right  ventricle ;  m,  right  auricle ;  n,  left  auricle;  o,  its  auricular  appendage;  the  second  letter 
o  below  indicates  the  left  ventricle. 

Fig.  246.  POSTERIOR  OR  LOWER  SURFACE  OF  THE  HEART,  b,  apex  of  the  heart ;  c,  the  four  pulmonary 
veins ;  d,  left  auricular  appendage ;  e.  termination  of  coronary  vein  into  the  right  auricle ;  /,  aorta ;  k, 
right  and  left  pulmonary  arteries ;  I,  right  ventricle ;  m,  right  auricle ;  n,  left  auricle;  o,  left  ventricle ; 
r,  orifice  of  the  inferior  cava. 

The  base  of  the  heart  is  directed  upward,  backward,  and  to  the  right, 
and  reaches  from  about  the  fourth  to  the  eighth  dorsal  vertebra.  The 
apex  or  point1  is  directed  downward,  forward,  and  to  the  left,  and  is 
opposite  the  sixth  costal  cartilage.  The  anterior  surface  is  convex,  and 
directed  upward  and  forward ;  the  posterior  surface  is  flattened,  and  in 
contact  with  the  diaphragm.  Of  the  two  sides  or  borders  the  left  one'2 
is  the  more  obtuse,  and  is  directed  obliquely  upward ;  the  right  one3  is 
the  longer,  and  is  directed  obliquely  downward. 

The  heart  is  a  hollow  muscular  organ  with  a  membranous  investment 
and  lining.  It  is  brown  in  color,  marked  with  white  membranous  streaks 
or  patches,  often  rendered  yellow  from  the  presence  of  adipose  tissue. 
Its  average  weight  is  about  ten  ounces ;  its  length  about  five  inches,  and 
its  breadth  about  three  and  a  half  inches.  Its  surface  exhibits  a  longi- 
tudinal and  a  transverse  groove4  which  indicate  a  division  of  the  organ 
into  four  parts,  named  auricles  and  ventricles. 

1  Mucro.  2  Margo  obtusus.  3  Margo  acutus. 

4  Sulcus  longitudinalis,  and  circularis,  or  coronalis. 


THE   VASCULAR   SYSTEM.  343 

The  Au'ricles1  are  thin-walled  cavities  forming  the  basal  portion  of 
the  heart,  and  are  so  called  from  their  fore  part  being  prolonged  into  an 
auricular  or  ear-like  appendage.  They  are  separated  by  a  partition,2 
and  are  connected  with  the  great  venous  trunks — the  cavae  and  pulmo- 
nary veins,  through  which  they  receive  the  blood  from  all  parts  of  the 
body.  They  communicate  with  the  ventricles,  each  by  a  large  aperture, 
the  auric'ulo-ventric'ular  orifice,3  which  is  furnished  with  a  remarkable 
mechanism  of  valves,  allowing  the  transmission  of  the  blood  from  the 
auricles  into  the  ventricles,  but  preventing  it  in  a  reverse  course. 

The  Ventricles4  are  thick-walled  cavities,  forming  the  more  massive 
portion  of  the  heart  toward  the  apex.  They  are  separated  by  a  parti- 
tion,5 and  are  connected  with  the  great  arterial  trunks — the  pulmonary 
artery  and  aorta — by  which  they  send  the  blood  to  all  parts  of  the  body. 
Another  remarkable  arrangement  of  valves  at  the  mouths6  of  the  vessels 
just  named  prevents  the  reflux  of  the  blood  into  the  ventricles. 

The  Right  Au'ricle7  consists  of  an  oblong  portion,  the  si'nus,8  with  a 
triangular,  somewhat  indented  auric'ular  appendage,9  which  projects 
forward  to  the  outer  side  of  the  origin  of  the  aorta.  Its  walls  are  thin 
and  translucent,  but  are  more  thickened  at  the  fore  and  outer  part,  and 
in  the  auricular  appendage,  by  means  of  isolated  fleshy  fasciculi  named 
pectinate  muscles.10  When  these  are  present,  the  interior  surface  of  the 
auricle  is  rendered  uneven  by  their  prominence,  but  elsewhere  it  is 
smooth. 

Into  the  back  part  of  the  right  auricle  the  superior  and  inferior  cavae 
open  with  a  direction  forward,  and  thus  produce  between  them  an  obtuse 
angle,11  which  is  slightly  prominent  on  the  interior  of  the  auricle/  The 
orifices  of  the  two  veins  are  unprotected  by  valves,  but  from  the  direc- 
tion of  the  two  vessels  their  currents  of  blood  are  not  opposed,  but 
cross  each  other  as  they  enter  the  auricle. 

On  the  interior  surface  of  the  right  auricle,  corresponding  with  the 
partition  separating  it  from  the  left  auricle,  there  exists  a  shallow  oval 
fossa12  or  depression,  surrounded  by  a  prominent  border.13  The  fossa 

1  Atria ;    sinus ;     cor    venosum  ;    cor  8  Sinus  dexter  cordis ;  sinus,  or  saccus 
membranosum ;  cavitates  innominatse.          venarum  cavarum ;  sinus  venosus. 

2  Septum  atriorum.  »  Auricula  cordis  dextra. 

SQstium  atrio-ventriculare ;     o.  ven-  10  Musculi  pectinati;  trabeculae   car- 

triculi  venosum  ;  ostium  venosum.  nese. 

4  Ventriculi ;  cor  arteriosum ;  cor  mus-  n  Tuberculum  Loweri. 
culosum ;  specus  cordis.  12  Fossa,  or  fovea  ovalis. 

5  Septum  ventriculorum.  13  Annulus   ovalis ;    limbus   foraminis 

6  Ostia  arteriosa.  ovalis ;  isthmus  Vieussenii. 
*  Atrium  dextrum;  a.  anterius ;  a.  ve- 
narum cavarum. 


344  THE  VASCULAR  SYSTEM. 

indicates  the  position  during  foetal  life  of  an  orifice,  named  the  oval  fora- 
men,1 by  which  the  two  auricles  communicate.  The  thin,  translucent 
bottom  of  the  fossa,  in  the  foetus,  forms  a  valve2  which  prevents  a 
reflux  of  blood  through  the  oval  foramen.  Not  unfrequently  the  up- 
per part  of  the  fossa  is  found  to  have  an  oblique  slit  remaining  as  part 
of  the  free  communication  of  the  auricles  in  foetal  life. 

Anterior  to  birth,  a  crescentic,  membranous  fold,  named  the  Eusta'- 
chian  valve,3  extends  from  the  right  of  the  orifice  of  the  inferior  cava, 
along  its  anterior  border  to  the  oval  foramen,  and  serves  to  direct  the 
current  of  blood  from  that  vessel  through  the  foramen.  In  the  adult, 
the  remains  of  this  valve,  usually  more  or  less  perforated  in  a  reticular 
manner,  are  still  observable. 

Between  the  left  extremity  of  the  Eustachian  valve  and  the  auriculo- 
ventricular  orifice  is  situated  the  aperture4,  of  the  coronary  vein,  pro- 
tected by  a  crescentic  valve.5  A  number  of  apertures6  of  small  veins 
are  also  to  be  detected  at  various  points  of  the  interior  surface  of  the 
right  auricle. 

The  right  auric'ulo-ventric'ular  orifice7  is  placed  in  advance  and  to 
the  left  of  that  of  the  inferior  cava.  It  is  oval,  about  an  inch  in 
diameter,  and  has  a  smooth,  slightly  prominent  border,8  giving  attachment 
to  the  tricuspid  valve. 

The  Left  Auricle9  has  a  cuboidal  sinus10  and  an  elongated,  indented 
auricular  appendage,  projecting  forward  to  the  left  of  the  origin  of  the 
pulmonary  artery.  Its  walls  are  thicker,  and  not  so  translucent  as  in  the 
right  auricle.  The  interior  surface  is  smooth,  except  within  the  auricular 
appendage,11  which  is  provided  with  pectinate  muscles. 

At  the  back  part  of  the  left  auricle  the  four  pulmonary  veins  open, 
two  on  each  side ;  and  their  orifices  are  unprotected  by  valves.  At  the 
lower  fore  part  of  the  cavity  is  situated  the  left  auriculo-ventricular 
orifice,12  which  is  constructed  like  that  in  the  right  side  of  the  heart. 

The  Eight  Ven'tricle13  is  pyramidal,  with  its  base  upward  and  back- 

1  Foramen  ovale;  f.  Botale;  f.  of  Bo-  cordis  venosus;  circulus  callosus  Hal- 
tal.  leri. 

2  Valvula  foraminis  ovalis.  9  Atrium  sinistrum. 

3  Valvula  Eustachii ;  valvula  forami-  10  Sinus  sinister  cordis  ;  s.  pulmonalis; 
nis  ovalis  anterior.  s.,  or  saccus  venarum  pulmonalium  ;  s. 

4  Orificium  venae  magnae  coronariae.  arteriosus  ;  atrium  cordis  sinistrum. 

5  Valvula  Thebesii.  n  Auricula  cordis  sinistra. 

6  Foramina  Thebesii.  12  Ostium  venosum  sinistrum. 

7  Ostium  atrio-ventriculare  dextrum ;  13  Ventriculus  dexter  ;  v.  anterior ;  v. 
ostium  venosum  dextrum.  pulmonalis  ;    v.  primus ;    cor  venosum  ; 

8  Annulus  fibro-cartilagineus  ;    tendo  cor  pulmonale. 


THE   VASCULAR  SYSTEM. 


345 


FIG.  247. 


ward,  and  joined  to  the  corresponding  auricle;  its  apex  is  downward  and 
forward,  and  does  not 
quite  reach  the  point  of 
the  heart.  It  occupies 
more  of  the  front  surface 
of  the  heart  than  the  left 
ventricle ;  and  its  walls, 
much  thinner  than  in  the 
latter,  are  about  the  fourth 
of  an  inch  in  thickness. 
The  left  wall,  which  forms 
the  partition1  between  the 
ventricles,  bulges  into  its 
cavity,  so  that  this  ap- 
pears crescentic  in  a  trans- 
verse section. 

The  interior  surface  of 
the  right  ventricle  is  ren- 
dered exceedingly  uneven 
by  numerous  projecting, 
rounded,  fleshy  fasciculi, 
named  the  carneous  col- 
umns.2 These  are  of  va- 
rious sizes,  and  pursue 

VIEW  OF  THE  HEART,  WITH  THE  ANTERIOR  PORTIONS  OF  THE  VEN- 
TRICLES REMOVED.  1,  interior  of  the  right  ventricle,  exhibiting  its 
carneous  columns ;  2,  left  ventricle ;  3,  right  auricle ;  4,  left  auricle; 
5,  aorta ;  6, 7,  the  two  divisions  of  the  mitral  valve ;  8,  posterior 
part  of  the  ventricle ;  9,  papillary  muscles  attached  by  tendinous 
cords  to  the  mitral  valve ;  10,  tricuspid  valve ;  11,  pulmonary  ar- 
tery laid  open ;  12,  one'of  the  semilunar  valves ;  the  other  two  are 
seen  in  section  on  each  side  of  the  former ;  13,  sinus  or  dilatation 
of  the  artery  behind  one  of  the  semilunar  valves. 


different  directions — 
springing  from  one  part 
of  the  walls,  sinking  into 
another,  and  producing 
an  intricate  interlace- 
ment. Some  of  them, 


larger  than  the  others, 
and  named  from  their  shape  pap'illary  muscles,3  project  from  the  ven- 
tricular wall  and  end  in  narrow  tendinous  cords,  which  are  inserted  into 
the  free  borders  of  the  tricuspid  valve. 

The  right  auric'ulo-ventric'ular  orifice4  opens  into  the  ventricle  at  the 
lower  back  part  of  its  base.  From  its  boundary  projects  a  broad 
membranous  fold,  irregularly  divided  into  three  parts,  and  named, 
from  this  circumstance,  the  tricus'pid  valve.5  The  free  borders  and 


1  Septum  ventriculorum. 

2  Columnse  carneae  ;  trabeculae  carneae; 
columnse,  trabeculae,  trabes,  funes,  fasci- 
culi teretes,  lacerti,  or  lacertuli  cordis. 


3  Musculi  papillares. 

4  Ostium  atrio-ventriculare  dextrum. 

5  Valvula   tricuspidalis ;  valvulae   tri- 
cuspides ;  v.  trisulcae  ;  v.  trigloclrines. 


346  THE   VASCULAR  SYSTEM. 

contiguous  under  surface  of  the  valve  are  attached  by  numerous  tendin- 
ous cords,1  as  above  indicated,  to  the  papillary  muscles,  and  also  to  inter- 
vening points  of  the  interior  surface  of  the  ventricle.  When  the  valve 
is  open,  the  divisions  project  into  the  cavity  of  the  ventricle  in  contact 
with  its  sides. 

In  structure,  both  the  tricuspid  valve  and  tendinous  cords  consist  of 
doublings  of  the  lining  membrane  of  the  heart,  strengthened  by  included 
fibrous  tissue. 

From  the  anterior  angle  of  the  base  of  the  right  ventricle,  the  pul- 
monary artery  has  its  origin.  The  orifice2  of  this  vessel  is  provided 
with  three  semilunar  valves,  and  the  interior  surface  of  the  ventricle  con- 
ducting to  it  is  smooth,  so  that  no  impediment  is  presented  to  the  cur- 
rent of  blood  in  its  passage  to  the  artery. 

The  semilunar  valves3  of  the  pulmonary  artery,  as  expressed  in  the 
name,  are  three  crescentic  membranous  doublings  arranged  in  a  circle. 
Their  convex  border  is  attached  around  the  boundary  of  the  orifice  of  the 
artery,  and  their  free  border  is  directed  into  the  latter.  Behind  each  valve 
the  artery  is  dilated  into  a  shallow  pouch  or  sinus,4  which  prevents  the 
valve,  when  open,  from  adhering  to  the  side  of  the  artery,  and  allows  the 
blood  in  its  reflux  to  get  behind  the  valve  and  press  it  down,  so  as  to 
meet  the  others  and  thus  close  the  orifice. 

The  semilunar  valves  are  doublings  of  the  vascular  lining  membrane, 
strengthened  by  included  fibrous  tissue.  The  latter  forms  a  nodule5  at 
the  middle  of  the  free  border  of  the  valves,  which  serves  as  a  common 
central  point  of  contact  when  they  are  closed.  Between  the  nodule  and 
the  ends  of  each  valve,  just  within  the  position  of  the  free  border,  there 
exists  a  pair  of  thin  lunated  spaces,6  arising  from  a  deficiency  of  the 
fibrous  basis  of  the  valve.  When  the  valves  are  shut,  these  spaces 
are  applied  by  their  opposed  surfaces  to  one  another,  and  completely 
prevent  the  entrance  of  blood  into  the  ventricle ;  while  the  force  of  the 
reflux  is  sustained  by  the  stronger  portions  of  the  valves. 

The  Left  Ven'tricle7  is  conical,  with  its  base  connected  to  the  corre- 
sponding auricle,  and  its  apex  forming  the  point  of  the  heart.  It  is 
longer,  and  contributes  more  to  the  posterior  surface  of  the  heart  than 

1  Chordae  tendineae.  Arantii,   or  Morgagni;    corpusculum 

2  Ostium  arteriosum  dextrum.  sesamoideum. 

3  Valvulae  semilunares ;  v.  sigmoidese  ;  6  Lunulae. 

processus  sigmoides.  7  Ventriculus  sinister ;  v.  aorticus ;  v. 

4  Sinus  of  Valsalva ;  sinus  pulmonalis.       posterior ;  v.  secundus  ;  cor  arteriosum; 

5  Corpusculus,    globulus,   or   nodulus       c.  aorticum. 


THE  VASCULAR  SYSTEM.  347 

the  right  ventricle.  Its  walls  are  three  times  as  thick  as  those  of  the 
latter,  and  its  transverse  section  is  circular.  Its  interior  surface  is  fur- 
nished with  more  numerous  and  stronger  carneous  columns,  which 
further  have  a  more  complex  arrangement ;  and  its  two  or  three  pap'- 
illary  muscles  are  also  more  robust. 

The  left  auric'ulo-ventric'ular  orifice,1  placed  at  the  back  part  of  the 
right  ventricle,  is  provided  with  a  pair  of  membranous  folds,  constituting 
the  mi'tral  valve.2  This  has  the  same  mechanism  and  purposes  as  the 
tricuspid  valve,  but  is  stronger. 

In  advance  and  to  the  right  of  the  orifice  just  indicated,  is  the  origin 
of  the  aorta,  which  is  provided  with  semilunar  valves,  identical  in 
character  with  those  of  the  pulmonary  artery,  and  differ  only  in  being 
stronger. 

STRUCTURE  OF  THE  HEART. 

As  previously  mentioned,  the  heart  is  muscular,  with  an  exterior  in- 
vestment of  serous  membrane  derived  from  the  pericardium,  and  with 
its  cavities  lined  by  the  endocar'dium.  This  is  a  thin,  translucent 
membrane,  continuous  with  that  of  the  blood-vessels. 

Doublings  of  the  endocardium,  thickened  with  intervening  fibrous  tis- 
sue, constitute  the  various  valves  of  the  interior  of  the  heart  and  the 
vascular  orifices  communicating  therewith.  In  structure  the  endocar- 
dium consists  of  an  epithelium  and  a  fibro-elastic  layer.  The  epithe- 
lium is  composed  of  a  layer  of  elongated,  flattened,  polygonal,  pave- 
ment-like cells.  The  fibro-elastic  layer  adheres  closely  to  the  muscular 
structure  beneath,  and  appears  to  be  defined  next  the  epithelium  by  an 
exceedingly  delicate  basement  membrane.  At  the  auriculo-ventricular 
orifices,  and  those  of  the  pulmonary  artery  and  aorta,  the  fibro-elastic 
tissue  forms  a  slightly  prominent  ring,3  which  gives  attachment  to  the 
valves,  and  affords  a  point4  of  departure  for  'most  of  the  muscular  fibres 
of  the  heart. 

The  muscular  structure  of  the  heart  is  composed  of  transversely 
striated  fibres,  which  exhibit  the  peculiarity  of  anastomosing,  or  of 
being  connected  by  means  of  numerous  short  oblique  offsets,  as  rep- 
resented in  figure  248.  The  muscular  fibres  are  much  smaller  than 
those  of  the  voluntary  muscles,  and  are  not  collected  into  bundles  as  in 

1  Ostium  atrio-ventriculare  sinistrum ;  s  Tendo  cordis  venosus  et  coronarius  ; 
ostiurn  venosum  sinistrum.                               annulus  fibro-cartilagineus ;  circulus  cal- 

2  Valvula   mitralis ;    v.  bicuspidalis ;       losus  Halleri. 
valvuloe    initrales;    v.   bicuspidatae ;    v.  4  Punctum  fixum. 
episcopales. 


348  THE   VASCULAR   SYSTEM. 

the  latter,  but  are  closely  approximated  with  comparatively  little  inter- 

vening  connective  tissue. 

The  arrangement  of  the  muscular 
fibres  of  the  heart  is  exceedingly 
complex.  In  the  auricles  a  thin 
layer  of  transverse  muscular  fibres 
encircles  both  together.  Beneath 
this  layer  is  another,  thicker  in  the 
left  than  the  right  auricle,  consist- 
ing of  loop-like  fibres  crossing  the 
direction  of  the  former,  and  at- 
STRIATED  MUSCULAR  TISSUE  OF  THE  HEART,  highly  tached  by  their  ends  to  the  fibrous 

rings    of  the    auriculo-ventricular 

orifices.    Other  muscular  fibres  are  arranged  in  circles  around  the  origin 
of  the  great  veins  and  the  auricular  appendages. 

In  the  ventricles,  some  of  the  muscular  fibres  are  common  to  both, 
while  others  belong  exclusively  to  each — the  left  one  possessing  many 
more  than  the  right  one.  Most  of  the  muscular  fibres  may  be  traced  from 
the  fibrous  rings  of  the  auriculo-ventricular  orifices,  and  those  of  the  pul- 
monary artery  and  aorta.  Those  seen  on  the  fore  part  of  the  heart  pursue 
a  course  downward,  from  right  to  left ;  while  those  on  the  back  of  the 
heart  take  a  more  longitudinal  course  in  the  opposite  direction.  At  the 
apex  of  the  heart  they  penetrate  in  a  whorl  to  the  interior  of  the  ventricles, 
where  they  terminate  in  the  carneous  columns,  some  of  them  forming  the 
papillary  muscles,  and  others  ascending  to  the  point  from  which  they 
started,  thus  describing  in  their  course  a  twisted  loop  like  the  Greek 
letter  «. 

The  arteries  supplying  the  structure  of  the  heart  are  the  right  and 
left  coronary.  The  course  of  their  trunks  will  be  given  hereafter. 
Their  branches  are  numerous,  and  the  capillaries  in  which  they  termi- 
nate generally  pursue  a  course  parallel  to  the  direction  of  the  mus- 
cular fibres,  as  in  other  muscular  structures.  Most  of  the  returning 
blood  is  emptied  directly  into  the  right  auricle  by  the  great  coronary 
vein,  and  the  remainder  is  returned  to  the  same  cavity  by  a  number  of 
minute  veins. 

The  lymphatics  are  numerous,  the  principal  ones  following  the  direc- 
tion of  the  coronary  veins  along  the  grooves  of  the  heart.  Those  of 
the  right  and  front  of  the  heart  for  the  most  part  join  the  anterior  mam- 
mary lymphatic  glands ;  those  of  the  left  and  back  of  the  heart  join  the 
bronchial  glands. 

The  nerves  of  the  heart  are  numerous  but  small,  and  are  derived  from 
the  cardiac  plexuses  of  the  pneumo-gastric,  spinal,  and  great  sympa- 
thetic nerves. 


THE   VASCULAR   SYSTEM.  349 


THE  PERICARDIUM. 

The  Pericar'dium1  is  the  fibro-serous  sac  inclosing  the  heart,  and  is 
attached  by  connective  tissue  to  the  pleura  of  each  side,  and  the  tendin- 
ous centre  of  the  diaphragm  below.  It  has  the  form  of  the  heart,  a 
bluish-white  color,  and  consists  of  two  layers. 

The  exterior  fibrous  layer2  is  a  strong  inextensible  membrane  com- 
posed of  interlacing  bundles  of  fibrous  tissue,  generally  pursuing  a  lon- 
gitudinal course.  It  embraces  the  origin  of  the  great  blood-vessels  at 
the  base  of  the  heart,  and  becomes  continuous  with  their  external  tunic. 

The  internal  serous  layer3  of  the  pericardium  has  the  general  ar- 
rangement and  constitution  of  serous  membranes  generally.  One  por- 
tion closely  invests  the  heart  and  the  commencement  of  the  great  blood- 
vessels at  its  base,  from  which  it  is  reflected  on  the  interior  of  the  fibrous 
layer  of  the  pericardium. 

The  cavity  of  the  pericardium  presents  smooth,  opposed  surfaces, 
bathed  with  a  serous  fluid,  the  pericardial  liquor,4  which  facilitates  the 
movements  of  the  heart. 

MECHANISM  OF  ACTION  OF  THE  HEART. 

The  heart,  by  alternate  contraction5  and  dilatation,6  is  the  motive 
power  in  the  circulation  of  the  blood,  though  there  are  also  several  other 
means  which  facilitate  the  latter.  The  motive  power  of  the  heart  resides 
in  its  muscular  walls,  which,  in  the  different  cavities,  correspond  in  strength 
with  the  distance  to  which  the  blood  is  to  be  sent.  Thus,  as  the  auricles 
transmit  the  blood  only  into  the  adjacent  cavities,  they  possess  thin  walls, 
while  those  of  the  right  ventricle,  which  sends  the  blood  to  the  lungs, 
are  thick — and  those  of  the  left  ventricle  are  thickest,  because  this  por- 
tion of  the  heart  transmits  the  blood  to  the  remotest  parts  of  the  body. 

The  pectinate  muscles  and  carneous  columns  are  accessory  powers  to 
the  general  walls,  but  are  always  so  situated  as  not  to  interfere  by  their 

1  Pericardion;  capsule,  or  sac  of  the  *  Liquor    pericardii;     aqua,    humor, 
heart ;  peribole ;  membrana  cor  circum-       lympha,  or  urina  pericardii ;  hydrocar- 
flexa ;  involucrum,  area,  arcula,  capsa,       dia. 

capsula,  camera,  indumentum,  pannicu-  5  Systole ;    systalsis,  contractio,  con- 
lus,  membrana,  theca,  saccus,  sacculus,  strictio,  augustatio,  submissio,  or  mica- 
scrotum,  vagina,  vesica,  thalamus  rega-  tio  cordis. 
lis,  bursa,  or  amphiesma  cordis.  «  Diastole ;  relaxatio,  or  remissio  cor- 

2  Fibrous  pericardium.  dis ;  motus  cordis  diastalticus. 

3  Serous  pericardium. 


350  THE   VASCULAR   SYSTEM. 

projection  with  the  course  of  the  currents  of  blood  passing  through  the 
heart.  Thus  the  spaces  between  the  two  cavaa  and  the  four  pulmonary  veins 
are  smooth,  as  are,  likewise,  the  approaches  to  the  auriculo-ventricular 
orifices,  the  pulmonary  artery,  and  aorta. 

The  uniform  direction  of  the  circulation  of  the  blood  is  maintained  by 
the  admirable  mechanism  of  valves  situated  in  the  heart,  at  the  origin  of 
the  great  arterial  trunks,  and  in  the  veins. 

The  auricles  dilate  and  receive  the  blood  simultaneously1 — the  right 
one  through  the  two  cavae  and  the  coronary  vein,  the  left  one  through 
the  four  pulmonary  veins.  The  auricles  then  contract  together,  and 
transmit  the  blood  through  the  auriculo-ventricular  orifices  into  the  ven- 
tricles. These  becoming  distended  now  contract2 — the  right  one  sending 
dark  blood  through  the  pulmonary  artery  to  the  lungs,  the  left  one 
sending  bright  red  blood  through  the  aorta  to  the  body  generally. 

In  the  contraction  of  the  ventricles  the  auriculo-ventricular  orifices 
are  closed  by  the  tricuspid  and  mitral  valves,  which  are  pressed  with 
their  edges  together  by  the  reflux  of  blood,  and  are  kept  stretched  by 
the  tendinous  cords,  just  as  the  sail  of  a  boat  is  kept  stretched  against 
the  wind  by  the  sheet  line. 

While  the  ventricles  contract  the  auricles  are  refilling.3 

The  blood  forced  by  the  ventricles  into  the  pulmonary  artery  and  aorta 
pushes  onward  the  column  of  blood  which  already  fills  these  vessels,  and 
likewise  causes  their  expansion. 

The  arteries  subsequently  react  or  contract  upon  their  contents,  and 
thus  continue  the  onward  impulse  of  the  current  of  blood,  while  its  re- 
flux closes  the  semilunar  valves  and  prevents  regurgitation  into  the  ven- 
tricles. This  alternate  expansion  and  contraction  of  the  arteries  con- 
stitutes their  pulsation,  or  the  pulse. 

The  number  of  dilatations  and  contractions  of  the  auricles  and  ventricles 
corresponds  with  the  pulsations  of  the  arteries  —  in  the  healthy  adult 
amounting  to  from  sixty  to  eighty  in  the  minute. 

The  action  of  the  heart  gives  rise  to  an  impulse  which  may  be  felt  on 
the  left  side  of  the  thorax  below  the  nipple,  opposite  the  interspace  of 
the  fifth  and  sixth  costal  cartilages. 

In  the  circulation  of  the  blood  from  the  heart  to  the  lungs  and  body 
generally,  and  then  back  again,  it  performs  two  circles.  The  smaller  of 
these,  named  the  lesser  or  pulmonary  circulation,  is  from  the  right  ven- 
tricle through  the  pulmonary  artery  to  the  lungs,  and  back  again  by  the 
pulmonary  veins  to  the  left  auricle.  The  larger  circle,  named  the  greater 

1  Synchronous  action  of  the  auricles.  3  Isochronous  action  of  the  ventricles 

2  Synchronous  action  of  the  ventricles.       and  auricles. 


THE  VASCULAR  SYSTEM.  351 

or  systemic  circulation,  is  from  the  left  ventricle  through  the  aorta  to 
all  parts  of  the  body,  and  thence  back  by  the  two  cavae  to  the  right 
auricle. 

Following  the  course  of  the  blood  in  succession,  and  starting  from  the 
right  auricle,  this  receives  the  dark  blood  of  the  body  through  the  supe- 
rior and  inferior  cava.  Contracting,  the  right  auricle  sends  the  blood 
into  the  corresponding  ventricle,  which  in  turn  sends  it  through  the  pul- 
monary artery  to  the  lungs.  Here  acquiring  a  bright-red  hue,  the  blood 
returns  through  the  four  pulmonary  veins  to  the  left  auricle,  which  then 
transmits  it  to  the  left  ventricle,  to  be  propelled  through  the  aorta  to  all 
parts  of  the  body,  from  whence  it  regains  the  heart  by  the  two  cavae. 

THE  ARTERIES. 

The  Ar'teries  consist  of  two  great  trunks  and  their  branches.  One  of 
these  trunks  is  the  aorta,  by  whose  branches  blood  is  conveyed  to  all 
parts  of  the  body  for  the  nutrition  of  the  organs ;  the  other  is  the  pul- 
monary artery,  which  distributes  the  blood  through  the  lungs  to  be 
aerated. 

THE  AORTA. 

The  Aor'ta1  is  the  main  trunk  of  the  arterial  system  supplying  blood 
to  the  body.  It  springs  from  the  left  ventricle  of  the  heart,  ascends 
and  arches  obliquely  from  the  right  to  the  left  of  the  vertebral  column, 
upon  which  it  then  descends  to  the  fourth  lumbar  vertebra,  and  there 
divides  into  the  common  iliac  arteries.  The  first  portion  of  its  course 
is  named  the  arch  of  the  aorta ;  and  the  descending  portion2  is  named, 
from  the  cavities  through  which  it  passes,  the  thoracic  and  abdominal 
aorta. 

THE  ARCH   OF  THE  AORTA. 

The  Arch  of  the  Aorta3  ascends  from  the  heart  with  a  slight  incli- 
nation toward  the  right  side,  curves  obliquely  backward  to  the  left  side 
over  the  right  pulmonary  artery  and  left  bronchus,  and  descends  to  the 
left  side  of  the  third  dorsal  vertebra,  where  it  becomes  the  thoracic  aorta. 
Its  commencement  is  concealed  by  the  root  of  the  pulmonary  artery  and 
right  auricular  appendage,  and  when  exposed  is  observed  to  present  a 
bulbous  appearance,4  due  to  the  dilatations5  behind  the  semilunar  valves. 

1  Arteria  magna ;  a.  maxima ;  a.  eras-  4  Bulbus  aortae. 

sa ;  haemal  axis.  5  Sinuses  of  Valsalva ;   lesser  sinuses 

2  Aorta  descendens.  of  Valsalva. 

3  Arcus  aortse. 


352 


THE   VASCULAR   SYSTEM. 


FIG.  249. 


The  ascending  portion1  of  the  arch  is  in  relation  behind  with  the  right 

pulmonary  artery  and  veins,  to  the 
right  with  the  superior  cava,  and  to 

monary  artery.  The  transverse 
portion  of  the  arch  rests  in  the  bi- 
furcation of  the  pulmonary  artery ; 
is  in  relation  above  with  the  left 
innominate  vein,  behind  with  the 
division  of  the  trachea,  and  in  front 
with  the  upper  part  of  the  sternum. 
The  descending  portion  of  the  arch 
is  in  relation  with  the  oesophagus 
and  thoracic  duct  to  the  right,  and 
with  the  root  of  the  left  lung  to 
the  left  and  in  front. 

Frequently  the  right  portion  of 
the  aortic  arch  exhibits  a  conspicu- 
ous dilatation,2  resembling  an  in- 
cipient aneurism,;  but  which  is  a 
natural  condition,  though  not  a 
constant  one. 

From  the  summit  of  the  arch  of 
the  aorta  spring  forth  the  large 
vessels  which  supply  the  head  and 
upper  extremities,  and  much  reduce 
the  diameter  of  the  descending  por- 
tion of  the  arch. 

The  branches  given  in  succession 
from  the  arch  of  the  aorta  are  as 
follow : — 

The  right  coronary  artery. 

The  left  coronary  artery. 

The  innominate  artery. 

The  right  common  carotid  artery. 
The  right  subclavian  artery. 

The  left  common  carotid  artery. 

The  left  subclavian  artery. 

The  coronary  arteries  arise  from 
the  aorta,  just  above  the  position 
of  the  semilunar  valves,  and  supply  the  walls  of  the  heart.     The  other 


THE  AORTA.  1,  arch  of  the  aorta;  2,  thoracic 
aorta;  3,  abdominal  aorta;  4,  innominate  artery; 
5,  right  common  carotid ;  6,  right  subclavian ;  7, 
left  common  carotid ;  8,  left  subclavian ;  9,  bron- 
chial artery,  a  small  branch  of  the  aorta ;  10,  reso- 
phageal  arteries;  11,  intercostal  arteries  of  the 
right  side  ;  12, of  the  left  side;  13,  phrenic  arteries; 
14,  coaliac  axis;  15,  coronary  artery;  16,  splenic 
artery  ;  17,  hepatic  artery;  18,  superior  mesenteric 
artery ;  19,  supra-renal  arteries  ;  20,  spermatic  ar- 
teries ;  21,  inferior  mesenteric  artery ;  22,  lumbar 
arteries ;  23,  common  iliac  arteries ;  24,  middle  sa- 
cral artery,  a,  aortic  orifice  of  the  diaphragm ;  6, 
articulation  of  the  head  of  the  ribs ;  c,  anterior 
scalene  muscle. 


1  Aorta  ascendens. 


2  Sinus  of  Valsalva ;  greater  sinus  of  Valsalva. 


THE  VASCULAR  SYSTEM.  353 

three  branches  spring  from  the  summit  of  the  arch  in  close  succession, 
and  are  the  large  vessels  which  supply  the  head  and  upper  extremities. 

I 

THE  CORONARY  ARTERIES. 

• 

m 
The  Right  Cor'onary  artery1  arises  from  the  aorta  just  above  its  right 

semilunar  valve,  and  winds  along  the  groove  between  the  right  auricle 
and  ventricle,  until  it  reaches  the  posterior  median  groove  of  the  ventri- 
cles, along  which  it  proceeds  to  the  apex  of  the  heart,  and  anastomoses 
with  the  left  coronary  artery.  It  supplies  the  right  side  of  the  heart 
and  the  posterior  portion  of  the  left  ventricle. 

The  Left  Cor'onary  artery2  arises  from  the  left  side  of  the  aorta  and 
passes  forward  between  the  pulmonary  artery  and  the  left  auricular  ap- 
pendage, and  divides  into  two  branches.  One  of  these  descends  the 
anterior  median  groove  of  the  ventricles  to  the  apex  of  the  heart,  where 
it  anastomoses  with  the  right  coronary  artery.  The  other  branch  winds 
along  the  groove  between  the  left  auricle  and  ventricle  to  the  back  of 
the  heart,  where  it  anastomoses  with  the  right  coronary  artery. 


THE  INNOMINATE  ARTERY. 

The  Innom/inate  artery3  is  the  first  of  the  three  large  vessels  spring- 
ing from  the  summit  of  the  arch  of  the  aorta,  and  corresponds  with  the 
other  two  in  supplying  branches  to  one-half  of  the  head  and  neck,  and 
one  upper  extremity.  It  is  about  an  inch  and  a  half  in  length  ;  ascends 
obliquely  toward  the  right  side,  in  front  of  the  trachea  and  behind  the 
left  innominate  vein,  and  divides  into  the  right  subclavian  and  right 
common  carotid  arteries  opposite  the  right  sterno-clavicular  articula- 
tion. 

As  an  occasional  variation,  the  innominate  artery  gives  off  the  left 
common  carotid  artery  ;  more  frequently  it  is  represented  by  its  ordinary 
divisions  springing  directly  from  the  aorta,  as  in  the  case  of  the  corre- 
sponding arteries  of  the  left  side. 

1  Arteria  coronaria  dextra.  2  A.  coronaria  sinistra. 

3  A.  innominata;  a.  annonyma;  a.  brachio-cephalica;  truncus  brachio-cephalicus ; 
right  subclavian  artery. 


354 


THE  VASCULAR   SYSTEM. 


THE  COMMON   CAROTID  ARTERY. 

The  Right  Common  Carot'id  artery1  is  one  of  the  divisions  of  the 
innominate  artery,  and  ascends  the  neck  to  the  upper  border  of  the 
larynx,  where  it  divides  into  the  external  and  internal  carotid  arteries. 

The  Left  Common  Carot'id  artery2  is  derived  from  the  arch  of  the 
aorta  next  in  succession  to  the  innominate  artery.  It  is  longer,  deeper, 
and  more  vertical  in  its  ascent  than  the  former,  and  divides  in  the  same 
position  and  manner. 

FIG.  250. 


LEFT  COMMON  CAROTID  DIVIDING  INTO  THE  EXTERNAL  AND  INTERNAL  CAROTID  ARTERIES.  1,  common  carotid 
artery;  2,  internal  carotid;  3,  external  carotid;  4,  superior  thyroid;  5,  lingual;  6,  pharyngeal  artery; 
7,  facial;  8,  inferior  palatine  and  tonsillar  arteries;  9,  submaxillary ;  10,  submental ;  11,  occipital ;  12, 
posterior  auricular ;  13,  parotid  branches ;  14,  internal  maxillary ;  15,  temporal  artery ;  16,  subclavian 
artery  ;  17,  axillary;  18,  vertebral  artery ;  19,  thyroid  axis;  20,  inferior  thyroid  giving  off  the  ascending 
cervical;  21,  transverse  cervical;  2J,  supra-scapular;  23,  internal  mammary  artery. 

The  Common  Carot'id  arteries,3  in  ascending  the  neck,  rest  upon  the 
muscles  in  front  of  the  cervical  vertebrae.  At  their  inner  side  the  tra- 
chea, larynx,  and  oesophagus  are  situated;  at  their  outer  side  is  the 


1  A.  carotis  communis  dextra;    a.  c. 
primitiva  dextra. 

2  A.  c.  c.  sinistra ;  a.  c.  p.  sinistra. 

3  Primitive  carotid   arteries ;  a.  caro- 


tides  ;  a.  caroticae ;  a.  capitales ;  a.  ce- 
phalic 93  ;  a.  jugulares ;  a.  soporales ;  a. 
somniferse  ;  a.  lethargicse  ;  a;  apoplecti- 
cse. 


THE  VASCULAR  SYSTEM.  355 

internal  jugular  vein,  which  is  inclosed  in  the  same  sheath,  with  the 
pneumogastric  nerve  interposed.  Behind  them  is  the  great  sympathetic 
nerve ;  and  in  front  they  are  crossed  by  the  omo-hyoid  muscle,  and  cov- 
ered by  the  sterno-mastoid  muscle. 

They  give  off  no  branches  until  they  reach  the  upper  margin  of  the 
larynx,  where  they  divide  into  the  external  and  internal  carotid  arteries. 

THE  EXTERNAL  CAROTID  ARTERY. 

The  External  Carot'id  artery1  on  each  side  supplies  all  the  parts  of 
the  head,  with  the  exception  of  the  brain  and  the  contents  of  the  orbits. 
Commencing  opposite  the  upper  border  of  the  larynx,  it  ascends  nearly 
vertically  to  the  space  between  the  neck  of  the  lower  jaw  and  the  auditory 
meatus,  where  it  divides  into  the  temporal  and  internal  maxillary  arteries. 
It  lies  in  front  and  to  the  inner  side  of  the  internal  carotid  artery,  close 
to  the  pharynx.  In  the  first  part  of  its  course  it  is  covered  only  by  the 
cervical  fascia,  subcutaneous  cervical  muscle,  and  skin;  then  is  crossed 
by  the  stylo-hyoid  and  digastric  muscles  and  the  hypoglossal  nerve ;  and 
afterwards  passes  through  the  substance  of  the  parotid  gland,  in  which 
it  is  crossed  by  the  facial  nerve. 

The  branches  given  off  by  the  external  carotid  artery  are  as  follow  : — 

1.  Superior  thyroid  artery. 

2.  Lingual  artery. 

3.  Pharyngeal  artery. 

4.  Facial  artery. 

5.  Occipital  artery. 

6.  Posterior  auricular  artery. 

7.  Muscular  branches. 

8.  Parotid  branches. 

9.  Temporal  artery. 

10.  Internal  maxillary  artery. 

1.  The  Superior  Thy'roid  artery2  comes  off  from  the  front  of  the  ex- 
ternal carotid,  just  above  its  commencement,  and  descends  obliquely  for- 
ward and  inward,  to  the  thyroid  body,  in  which  it  is  mainly  distributed  ; 
anastomosing  with  the  other  arteries  of  that  organ.  In  its  course  it  is 
crossed  by  the  omo-hyoid  muscle,  and  gives  off  the  following  named 
branches  : — 

a.  Hyoid  Branch. 

b.  Muscular  branches. 

c.  Laryngeal  artery. 

1  A.  carotis  externa ;  a.  carotis  facialis ;  a.  pericephalica. 

2  A.  thyroidea  superior ;   a.  laryngea  superior ;   a.  gutteralis  superior. 


356  THE  VASCULAR  SYSTEM. 

a.  The  Hy'oid  branch1  is  a  small  vessel  running  along  the  side  of  the 
hyoid  bone,  and  supplying   the  contiguous  parts.     It  is  frequently  a 
branch  of  the  lingual  artery. 

b.  The   Muscular  branches2   are   distributed  to  the  sterno-raastoid 
muscle  and  the  depressors  and  elevators  of  the  hyoid  bone  and  larynx. 

c.  The  Larynge'al   artery3  pierces  the  thyro-hyoid   membrane,  and 
supplies  the  small  muscles  and  mucous  membrane  of  the  larynx. 

2.  The  Lin'gual  artery,4  larger  than  the  preceding  branch  of  the 
carotid,  comes  off  next  to  it,  on  a  line  with  the   side  of  the  hyoid 
bone.     After   advancing  just   above  the  great  horn  of  the  latter,  it 
ascends  between  the  hyo-glossal  muscle  and  the  middle  constrictor  of  the 
pharynx,  to  the  under  part  of  the  tongue,  along  which  it  proceeds  to  the 
tip.     Its  branches  are  as  follow  : — 

a.  Dorsal  lingual  artery. 

b.  Sublingual  artery. 

c.  Kanine  artery. 

a.  The  Dorsal  lin'gual   artery,5  frequently  represented  by  several 
small  branches,  supplies  the  root  of  the  tongue. 

b.  The  Sublin'gual  artery6  passes  between  the  mylo-hyoid  muscle 
and  the  sublingual  gland,  and  supplies  both  with  branches. 

c.  The  Ran'ine  artery7  is  the  continuation  forward  of  the  lingual, 
between  the  hyo-glossal  tand  genio-glossal  muscles,  to  the  tip  of  the 
tongue.     It  has  a  tortuous  course  ;  and  at  the  side  of  the  iraenum  of  the 
tongue  is  covered  only  by  the  mucous  membrane. 

3.  The  Pharynge'al  artery8  is  a  long,  narrow  vessel,  derived  from  the 
inner  side  of  the  external  carotid  artery,  nearly  on  a  level  with  the  pre- 
ceding branch.     It  lies  concealed  in  the  ordinary  view  of  the  vessels,  and 
ascends  deeply  in  the  neck,  on  the  surface  of  the  pharynx,  to  the  base  of 
the  skull.    In  its  course  it  supplies  branches  to  the  pharynx,9  soft  palate, 
and   tonsils,  the   muscles   in   front  of  the   cervical  vertebrse,  and   the 
nerves  which  pass  through  the  jugular  foramen.      It  also  gives  small 
branches10  to  the  dura  mater  through  the  jugular  and  lacerated  foramina. 


1  Ramus  hyoideus.  7  A.  ranina ;  a.  profunda  linguae. 

*  R.  musculares.  8  A.  pharyngea ;   a.  pharyngea  ascen- 

3  R.  laryngea;  r.  1.  superior.  dens,  or  inferior. 

4  A.  lingualis.  9  Rami  pharyngei. 

5  A.  dorsalis  linguae.  10  A.  meningeae  posteriores 

6  A.  sublingualis. 


THE   VASCULAR  SYSTEM. 


357 


THE  EXTERNAL  CAROTID  ARTERY  AND  ITS  BRANCHES.  1,  right  common  carotid  ;  2,  internal  carotid  ;  3,  ex- 
ternal carotid;  4,  superior  thyroid;  5,  lingual;  6,  facial;  7,  submental  ;  8,  inferior  coronary;  9,  superior 
coronary;  10,  muscular  branches  ;  11,  lateral  nasal  artery;  12,  angular  artery;  13,  occipital  artery  ;  14, 
descending  cervical;  15,  muscular  branch;  16,  posterior  auricular  artery;  17,  parotid  branches;  18,  in- 
ternal maxillary;  19,  temporal;  20,  transverse  facial;  21,  anterior  auricular;  22,  supra-orbital;  23,  middle 
temporal  ;  24,  anterior  temporal  ;  25,  posterior  temporal  artery. 

4.  The  Fa'cial  artery1  comes  from  the  external  carotid  just  above 
the  lingual,  and  is  about  the  same  size  as  this.  It  passes  upward  and 
forward  through  the  submaxillary  gland,  curves  over  the  base  of  the 
lower  jaw  in  advance  of  the  insertion  of  the  masseter  muscle,  and 
ascends  upon  the  face  in  a  tortuous  manner  to  the  angle  of  the  mouth, 
and  thence  to  the  inner  angle  of  the  eye.  Below  the  jaw  it  passes 
beneath  the  stylo-hyoid  and  digastric  muscles  ;  at  the  base  of  the  jaw  is 
only  covered  by  the  skin  and  subcutaneous  cervical  muscle  ;  and  at  the 
angle  of  the  mouth  is  beneath  the  depressor  of  the  oral  angle  and  the 
zygomatic  muscles.  Its  principal  branches  are  as  follow  :  — 

a.  Inferior  palatine  artery. 

b.  Tonsillar  artery. 

c.  Submaxillary  branches. 

d.  Submental  artery. 


1  A.  facialis;  a.  maxillaris  externa;  a.  labialis;  a.  angularis;  a.  palato-labialis. 


358  THE  VASCULAR   SYSTEM. 

e.  Inferior  coronary  artery. 
/.  Superior  coronary  artery. 
g.  Muscular  branches. 
h.  Lateral  nasal  artery. 
i.  Angular  artery. 

a.  The  Inferior  pal'atine  artery1  ascends  at  the  side  of  the  pharynx, 
and  gives  branches  to  the  internal  pterygoid  muscle,  the  styloid  muscles, 
the  tonsil,  Eustachian  tube,  and  muscles  and  mucous  membrane  of  the 
soft  palate.  It  is  sometimes  a  branch  of  the  pharyngeal  artery. 

6.  The  Ton'sillar  artery2  ascends  at  the  side  of  the  pharynx  to  the 
fauces  and  tonsil. 

c.  The  Submax'illary  branches3  are  small  vessels  which  supply  the 
submaxillary  gland. 

d.  The   Submen'tal    artery,4    larger    than    any   of   the    preceding 
branches,  passes  forward  between  the  digastric  and  mylo-hyoid  muscles, 
and  winds  over  the  chin  to  anastomose  with  the  inferior  coronary  artery. 
In  its  course  it  supplies  the  contiguous  muscles,  the  submaxillary  gland, 
and  the  chin. 

e.  The  Inferior  cor'onary  artery5  is  derived  from  the  facial  as  it  ap- 
proaches the  angle  of  the  mouth.    Passing  forward  and  upward,  beneath 
the  depressor  of  the  oral  angle,  it  enters  the  orbicular  muscle  of  the  lower 
lip,  and  pursues  a  tortuous  course  to  join  its  fellow  of  the  opposite  side. 

f.  The  Superior  cor'onary  artery6  comes  from  the  facial  at  the  angle 
of  the  mouth,  and  pursues  a  tortuous  course  in  the  upper  lip  to  join  the 
corresponding  vessel  of  the  other  side.     Besides  supplying  the  lip,  it 
gives  a  branch  to  the  partition  of  the  nose.7 

g.  The  Muscular  branches8  are  small  and  variable  vessels  supplying 
the  depressor  of  the  oral  angle,  the  masseter,  buccinator,  zygomatic,  and 
other  muscles. 

h.  The  Lateral  na'sal  artery,9  frequently  represented  by  several 
smaller  branches,  passes  inward,  and  supplies  the  side  of  the  nose. 

i.  The  Angular  artery,10  the  termination  of  the  facial,  inosculates  with 
branches  of  the  ophthalmic  artery. 


1  A.  palatina  inferior,  or  ascendens;  a.  6  A.  coronaria  superior;  a.  labialis  su- 
pharyngo-palatina.  perior. 

2  A.  tonsillaris.  "  A.  septi  narium. 

3  Kami  submaxillares ;  r.  glandulares.  8  Kami  musculares ;  r.  buccales,  mas- 

4  A.  submentalis.  »  seterici,  etc. 

5  A.  coronaria  inferior ;  a.  labialis  in-          9  A.  nasalis  lateralis,  or  externa  and  ra- 
ferior.  mi  pinnales  and  dorsales  nasi. 

10  A.  angularis. 


THE  VASCULAR  SYSTEM.  359 

5.  The  Occip'ital  artery1  springs  from  the  back  part  of  the  external 
carotid,  about   as   high  as  the  former   branch,  and   passes  backward 
beneath  the  muscles  attached  to  the  mastoid  process  of  the  temporal 
bone.     Pursuing  its  course  between  the  splenius  and  complex  muscles, 
at  the  back  of  the  neck,  it  pierces  the  cranial  attachment  of  the  trapezius 
muscle,  and  ascends  beneath  the  skin  of  the  occipital  region,  where  it 
divides  into  many  branches,  which  anastomose  with  the  posterior  auric- 
ular and  temporal  arteries. 

In  its  course  it  gives  off  the  following  branches : — 

a.  Muscular  branches. 

&.  Descending  cervical  artery. 

c.  Meningeal  branch. 

a.  The  Muscular  branches2  go  to  the  sterno-mastoid,  digastric,  and 
other  muscles. 

b.  The  Descending  cer'vical  artery3  passes  down  the  back  of  the 
neck,  and  divides  into  branches  which  supply  the  complex,  splenius,  and 
other  muscles. 

c.  The  Menin'geal  branch4  is  a  small  vessel  ascending  through  the 
jugular  foramen  to  be  distributed  to  the  dura  mater. 

6.  The  Posterior  Auric'ular  artery5  is  a  small  vessel  which  comes  off' 
from  the  external  carotid  a  short  distance  above  the  former  branch.     It 
ascends  between  the  lower  part  of  the  parotid  gland  and  the  mastoid 
process  to  the  side  of  the  head  behind  the  ear,  where  it  divides  into 
branches  supplying  the  latter,  and  anastomosing  with  the  occipital  artery. 
In  its  course  it  gives  off  a  small  but  important  branch,  as  follows  NT— 

a.  The  Sty'lo-mastoid  artery,6  which  enters  the  foramen  of  that  name, 
and  ascends  to  supply  the  tympanum  and  its  contents,  and  the  mastoid 
sinuses. 

7.  The  Muscular  branches7  of  the  external  carotid,  irregular  in  size 
and   disposition,  supply  the   sterno-mastoid,  masseter,   and   pterygoid 
muscles. 

8.  The  Parot'id  branches8  are  small  vessels  given  to  the  parotid  gland 
in  the  course  of  the  carotid  artery  through  it. 

1  A.  occipitalis.  *  A.  meningea ;  a.  m.  posterior  externa ; 

2  Rami   musculares ;  r.  cervicales ;   r.  ramus  meningeus. 
sterno-mastoideus,  etc.  5  A.  auricularis  posterior. 

3  A.  cervicalis  descendens;  a.  cervicalis          6  A.  stylo-mastoidea. 

superior  profunda  and  superficialis ;  a.  7  Rami  musculares ;  ramus  sterno-mas- 

princeps  cervicis.  toideus,  massetericus,  etc. 

8  R.  parotidei. 


360  THE   VASCULAR   SYSTEM. 

9.  The  Tem'poral  artery,1  the  apparent  continuation  of  the  external 
carotid,  ascends  through  the  parotid  gland  in  front  of  the  ear  to  the 
temple,  where  it  is  situated  between  the  skin  and  temporal  fascia.  A 
short  distance  above  the  zygoma  it  divides  into  two  branches,  which 
ramify  on  the  side  of  the  head  immediately  beneath  the  integument. 
The  branches  of  the  temporal  artery,  including  the  terminal  ones,  are  as 

follow  : — 

a.  Transverse  facial  artery. 

b.  Anterior  auricular  arteries. 

c.  Supra-orbital  artery. 

d.  Middle  temporal  artery. 

e.  Anterior  temporal  artery. 
/.  Posterior  temporal  artery. 

a.  The  Transverse  fa'cial  artery2  aris.es  from  the  temporal,  while  it 
is  involved  in  the  parotid  gland,  and  passes  across  the  masseter  muscle, 
between  the  zygoma  and  parotid  duct,  to  the  upper  part  of  the  cheek. 
It  supplies  the  parotid  gland,  masseter,  palpebral  orbicular,  and  other 
muscles,  and  anastomoses  with  branches  of  the  ophthalmic  and  facial 
arteries.     It  is  often  represented  by  several  smaller  branches. 

b.  The  Anterior   auric'ular  arteries3  are  several  small  vessels  dis- 
tributed to  the  front  of  the  ear  and  the  auditory  meatus. 

c.  The  Supra-orVital  artery4  arises  above  the  zygoma  and  ascends  to 
the  supra-orbital  margin,  where  it  anastomoses  with  branches  of  the 
ophthalmic  and  anterior  temporal  arteries. 

d.  The  Middle  tem'poral  artery5  perforates  the  temporal  fascia,  just 
above  the  zygoma,  and  is  distributed  to  the  temporal  muscle. 

e.  The  Anterior  tem'poral  artery,6  one  of  the  terminal  branches  of 
the  temporal,  curves  forward  and  upward  upon  the  temple  and  forehead, 
and  divides  into  numerous  branches,  supplying  the  scalp  and  contiguous 
muscles,  and  anastomosing  with  branches  of  the  ophthalmic  and  posterior 
temporal  arteries. 

/.  The  Posterior  tem'poral  artery,7  larger  than  the  former,  turns 
upward  and  backward  at  the  side  of  the  head,  and  divides  into  numerous 
branches,  anastomosing  with  the  anterior  temporal,  posterior  auricular, 
and  occipital  arteries. 

1  A.  temporalis;  a.  crotaphitica.  5  A.  temporalis  media. 

a  A.  transversa  faciei.  6  A.  temporalis  anterior ;  a.  t.  superfi- 

3  A.  auriculares  anteriores ;  a.  auricu-  cialis  anterior ;    a   t.  frontalis  ;  a.  t.  in- 
lares  anteriores  inferiores,  and  a.  auricu-  terna. 

laris  anterior  superior.  7  A.  temporalis  posterior;  a.  t.  superfi- 

4  A.  supra-orbitalis  ;  a.  supra-orbitalis       cialis  posterior ;  a.  t.  occipitalis ;  a.  t.  ex- 
externa ;  a.  zygomatico-orbitalis.  terna. 


,  THE  VASCULAR  SYSTEM.  361 

10.  The  Internal  Max'illary  artery,1  the  larger  division  of  the  exter- 
nal  carotid,  passes  behind  the  neck  of  the  jaw,  horizontally  forward  be- 
tween the  pterygoid  muscles.  If  then  ascends  a  short  distance,  and 
again  turns  forward  and  inward  to  the  upper  part  of  the  pterygo-maxil- 
lary  fossa,  where  it  divides  into  two  terminal  branches — the  descending 
palatine  and  the  spheno-palatine  arteries.  Including  the  latter,  the 
internal  maxillary  gives  off  the  following  branches  : — 

a.  Tympanic  artery. 

b.  Great  meningeal  artery. 

c.  Small  meningeal  artery. 

d.  Inferior  maxillary  artery. 

e.  Muscular  branches. 

/.  Superior  maxillary  artery. 
g.  Infra-orbital  artery. 
7i.  Descending  palatine  artery. 
i.  Spheno-palatine  artery. 

a.  The  Tym'panic  artery,2  a  small  vessel  given  from  the  internal 
maxillary  near  its  origin,  ascends  behind  the  maxillary  articulation  and 
passes  through  the  glenoid  fissure  to  be  distributed  to  the  tympanum. 

b.  The  Great  menin'geal  artery3  comes  from  the  internal  maxillary, 
a  short  distance  from  the  preceding,  and  ascends  to  the  spinous  foramen 
of  the  sphenoid  bone,  through  which  it  enters  the  middle  cerebral  fossa 
of  the  cranial  cavity.     It  here  curves  forward  and  outward  between  the 
dura  mater  and  the  temporal  bone,  and  divides  into  two  branches,  which 
ascend  and  ramify  between  the  membrane  just  mentioned  and  the  parietal 
bone.     It  produces  the  arborescent  channels  on  the  interior  surface  of 
the  latter,  and  supplies  both  the  dura  mater  and  the  cranial  vault. 

In  its  course  it  gives  branches  to  the  elevator  and  tensor  muscles  of 
the  palate,  and  to  the  semilunar  ganglion  of  the  trifacial  nerve. 

c.  The  Small  meningeal  artery,4  frequently  a  branch  of  the  preced- 
ing, enters  the  cranium  through  the  oval  foramen,  and  supplies  the  dura 
mater  of  the  middle  cerebral  fossa. 

d.  The  Inferior  max'illary  artery5  comes  from  the  internal  maxillary 
nearly  opposite  the  meningeals,  and  descends,  in  company  with  the  infe- 
rior dental  nerve,  to  enter  the  dental  canal  of  the  lower  jaw.      In  its 


1  A.  raaxillaris    interna :    a.  gutturo-      a.  m.  spinosa ;    a.  spinosa ;    a.  spheno- 
maxillaris.  spinosa ;  a.  durae  matris  media  maxima. 

2  A.  tympanica.  4  A.  meningea  parva. 

3  A.  meningea  magna  ;    a.  m.  media ;  5  A.  maxillaris  inferior ;    a.  dentalis, 

or  alveolaris  inferior. 


362 


THE   VASCULAR   SYSTEM. 


passage  through  this  canal  it  gives  off  the  fine  dental  arteries1  to  the 
teeth,  and  finally  emerges  at  the  mental  foramen  to  terminate  in  the  chin,2 

where  it  anastomoses 
with  the  submental  and 
inferior  coronary  arteries. 
Before  entering  the  dental 
canal  it  gives  off  a  branch3 
which  runs  along  the  mo- 
lar ridge  and  supplies  the 
gum  and  the  mylo-hyoid 
muscle. 

e.  The  Muscular 
branches,4  given  off  be- 
tween the  pterygoid  mus- 
cles, usually  consist  of 
two5  to  the  latter,  two6 
to  the  temporal  muscle, 
one7  to  the  masseter,  and 
one8  to  the  buccinator. 

/.  The  Superior  max'- 
illary  artery9  is  given  off 
from  the  internal  maxil- 
lary as  it  escapes  from  be- 
tween the  pterygoid  mus- 
cles. It  descends  upon 
the  tuberosity  of  the  max- 
illary bone,  and  gives  off 
branches  to  the  gum,  and 
the  posterior  dental  ar- 
teries which  enter  small  foramina  of  the  bone  to  supply  the  maxillary 
sinus  and  the  molar  teeth. 

g.  The  Infra-orVital  artery10  arises  near  the  preceding,  and  enters  the 
infra-orbital  canal,  along  which  it  runs  to  the  face.  In  its  course  through 
the  canal  it  gives  off  the  anterior  dental  arteries  to  the  front  teeth,  and 
small  branches  to  the  inferior  straight  and  oblique  muscles  of  the  orbit. 


INTERNAL  MAXILLARY  ARTERY.  1,  right  common  carotid ;  2,  in- 
ternal carotid ;  3,  external  carotid ;  4,  superior  thyroid ;  5,  lin- 
gual; 6,  facial;  7,  occipital;  8,  posterior  auricular;  9,  parotid 
branch;  10,  temporal  artery;  11,  internal  maxillary;  12,  tym- 
panic ;  13,  the  great  and  small  meningeal  arteries  from  a  common 
branch ;  14,  inferior  dental  artery ;  15,  muscular  branches ;  16, 
superior  maxillary  artery  giving  off  the  posterior  dental  arteries ; 
17,  18,  infra-orbital  artery. 


1  A.  dentales ;  rami  alveolares. 

2  A.  mentalis. 

3  A.  mylohyoidea. 

4  Rami  musculares. 

5  A.  pterygoidese. 

6  A.  temporales  profundge ;  a.  tempo- 
rails  profunda  posterior  and  anterior. 


7  A.  masseterica. 

8  A.  buccinatoria ;  a.  buccalis. 

9  A.    maxillaris    superior ;    a.   supra- 
maxillaris ;  a.  dentalis ;  a.  alveolaris  su- 
perior. 

10  A.  infra-orbitalis. 


THE   VASCULAR  SYSTEM. 

On  the  face  it  gives  branches  to  the  lower  eyelid  and  upper  lip,  and 
anastomoses  with  branches  of  the  facial  and  ophthalmic  arteries. 

h.  The  Descending  pal'atine  artery,1  one  of  the  terminal  branches  of 
the  internal  maxillary,  descends  through  the  posterior  palatine  canal 
and  is  distributed  to  the  soft  and  hard  palate.  One2  of  its  branches 
reaches  the  front  of  the  hard  palate,  and  anastomoses,  through  the  ante- 
rior palatine  foramen,  with  the  arteries  of  the  nose.  Another  branch,3 
near  the  origin  of  the  artery,  turns  back  through  the  pterygoid  canal  and 
reaches  the  top  of  the  pharynx. 

i.  The  Spheno-pal/atine  artery,4  the  second  division  of  the  internal 
maxillary,  passes  into  the  cavity  of  the  nose  through  the  spheno-pala- 
tine  foramen,  and,  after  sending  a  small  branch5  backward  through  the 
pterygo-palatine  canal  to  the  upper  part  of  the  pharynx,  divides  into 
two  branches.  One6  of  these  is  distributed  to  the  lateral  wall  and  floor 
of  the  nose,  and  to  the  maxillary  sinus.  The  other  branch7  descends 
upon  the  partition  of  the  nose  to  which  it  is  distributed,  anastomosing, 
through  the  anterior  palatine  foramen,  with  a  branch  of  the  descending 
palatine  artery. 

THE  INTERNAL  CAROTID  ARTERY. 

The  Internal  Carot'id  artery,8  the  second  division  of  the  common 
carotid  artery,  destined  to  supply  the  brain  and  contents  of  the 
orbit,  ascends  in  a  nearly  straight  line  to  the  carotid  canal  of  the  tem- 
poral bone.  Winding  through  this  canal,  it  enters  the  cranial  cavity 
above  the  lacerated  foramen,  and  proceeds  forward  along  the  side  of  the 
body  of  the  sphenoid  bone  to  the  anterior  clinoid  process,  where  it  turns 
upward  to  the  fissure  separating  the  anterior  and  middle  lobes  of  the 
brain,  and  divides  into  the  anterior  and  middle  cerebral  arteries. 

In  the  neck  the  internal  carotid  gives  off  no  branches,  and  rests  against 
the  muscles  in  front  of  the  cervical  vertebra.  To  its  inner  side  is  the 
pharynx ;  in  front  of  it  the  external  carotid  artery ;  and  externally  and 
behind  are  the  internal  jugular  vein  and  the  last  four  cerebral  nerves. 
At  the  side  of  the  body  of  the  sphenoid  bone,  it  is  inclosed  in  the  lower 
wall  of  the  cavernous  sinus,  and  at  the  anterior  clinoid  process  pierces 
the  dura  mater  to  reach  the  brain. 

1  A.  palatina  descendens ;  a.  palatina  5  A.  pharyngea   suprema,  or   descen- 
superior;  a.  pterygo-palatina.  dens. 

2  A.  palatina  anterior.  6  A.  nasalis  posterior  externa,  or  late- 

3  A.  Vidiana.  ralis. 

4  A.  spheno-palatina ;    a.  nasalis  pos-  *  A.  septi  narium  posterior. 

terior.  8  ^  carotis  interna ;   a.  carotis  cere- 

bralis  ;  a.  cerebralis ;  a.  encephalica. 


364 


THE   VASCULAR   SYSTEM. 


The  branches  of  the  internal  carotid  artery  are  as  follow  : — 

1.  Ophthalmic  artery. 

2.  Posterior  communicating  artery. 

3.  Choroid  artery. 

4.  Anterior  cerebral  artery. 

5.  Middle  cerebral  artery. 

1.  The  Ophthal'mic  artery1  springs  from  the  internal  carotid,  within 
the  position  of  the  anterior  clinoid  process,  immediately  after  it  pierces 

FIG.  253. 


ARTERIES  OF  THE  INTERIOR  OF  THE  CRAMUM.  1,  internal  carotid  arteries;  2,  ophthalmic  artery;  3,  pos- 
terior communicating  arteries;  4,  anterior  cerebral  arteries;  5,  anterior  communicating  artery;  6,  mid- 
dle cerebral  arteries ;  7,  lachrymal ;  8,  short  ciliary  arteries  piercing  the  back  part  of  the  eyeball ;  9,  cen- 
tral retinal  piercing  the  optic  nerve  to  reach  the  interior  of  the  eyeball;  10,  muscular  artery;  11,  frontal 
and  nasal  artery;  12,  vertebral  arteries ;  13,  posterior  meningeal  artery;  14,  posterior  spinal  artery;  15, 
anterior  spinal  arteries  conjoining  in  a  single  one ;  16,  inferior  cerebellar  arteries,  17  basilar  artery  formed 
by  the  union  of  the  vertebrals;  18,  internal  auditory;  19,  superior  cerebellar;  20,  posterior  cerebral 
arteries. 

the  dura  mater,  and  passes  through  the  optic  foramen  beneath  and 
to  the  outer  side  of  the  optic  nerve.  Within  the  orbit  it  pursues  a 
tortuous  course  above  the  optic  nerve  and  along  the  inner  wall,  and  di- 
vides into  two  terminal  branches — the  frontal  and  nasal.  The  branches 
of  the  ophthalmic  artery,  including  the  latter,  are  as  follow : — 

1  A.  ophthalmica  •  a.  orbitalis. 


THE   VASCULAR  SYSTEM.  365 

a.  Lachrymal  artery. 

6.  Central  retinal  artery. 

c.  Long  ciliary  arteries. 

d.  Short  ciliary  arteries. 

e.  Muscular  arteries. 
/.  Supra-orbital  artery. 

g.  Posterior  ethmoidal  artery. 
h.  Anterior  ethmoidal  artery. 
i.   Palpebral  arteries. 
j.   Frontal  artery. 
k.  Nasal  artery. 

a.  The  Lach'rymal  artery1  passes  along  the  outer  part  of  the  orbit 
to  the  lachrymal  gland,  in  which  it  is  mainly  distributed.     Some  of  its 
branches  supply  several  of  the  contiguous  muscles ;  others  pass  through 
the  foramina  of  the  malar  bone  to  anastomose  with  branches  of  the 
facial  and  internal  maxillary  arteries ;  some  pierce  the  sclerotic  tunic  as 
ciliary  arteries,  and,  finally,  others2  pass  from  the  outer  canthus  of  the 
eye  to  the  eyelids. 

b.  The  Central  ret'inal  artery3  penetrates  the  optic  nerve,  and  through 
it  enters  the  eyeball  to  ramify  in  the  inner  layer  of  the  retina.     In  the 
foetus  a  branch  of  it  passes  through  the  axis  of  the  vitreous  humor  to 
reach  the  capsule  of  the  crystalline  lens. 

c.  The  Long  cil'iary  arteries,4  two  in  number,  pierce  the  back  of  the 
eyeball  and  run  forward,  one  on  each  side,  between  the  choroid  and  scle- 
rotic coat,  to  the  iris,  in  which  they  are  distributed. 

d.  The  Short  cil'iary  arteries,5  three  or  four  in  number,  pierce  the 
back  of  the  sclerotic  coat,  and  are  distributed  to  the  choroid. 

e.  The  Muscular  arteries6  are  given  off  to  all  the  muscles  of  the  eye- 
ball.    From  these  arise  the  anterior  ciliary  arteries,7  which  consist  of 
from  five  to  ten  minute  branches  penetrating  the  front  of  the  sclerotic 
coat  to  be  distributed  to  the  iris. 

/.  The  Supra-orb'ital  artery8  passes  along  the  roof  of  the  orbit,  and 
through  the  supra-orbital  foramen,  to  the  skin  and  muscles  of  the  eye- 
brow and  forehead. 

g.  The  Posterior  ethmoid'al  artery9  enters  the  corresponding  fora- 
men, and  is  distributed  to  the  posterior  ethmoidal  sinuses  and  the  dura 
mater. 

1  A.  lachrymalis.  5  ^.  ciliares  posticae  breves ;  a.  uveales. 

2  A.  palpebralis  externa  superior  and          6  A.  musculares. 
inferior.  7  A.  ciliares  anteriores. 

3  A.  centralis  retinae  ;  a.  c.  Zinnii.  8  A.  supra-orbitalis ;   a.  superciliaris. 
*  A.  ciliares  posticaj  longae ;  a.  iridis.  9  A.  ethmoidalis  posterior. 


366  THE   VASCULAR   SYSTEM. 

h.  The  Anterior  ethmoid'al  artery1  enters  the  corresponding  foramen, 
and  gives  off  a  menin'geal  branch2  to  the  dura  mater,  and  the  anterior 
nasal  artery,3  which  enters  the  nose,  through  the  most  anterior  of  the 
foramina  of  the  cribriform  plate,  to  be  distributed  to  the  front  part  of 
the  nose  and  the  anterior  ethmoidal  and  frontal  sinuses. 

1.  The  Pal'pebral  arteries4  come  from  the  ophthalmic  at  the  inner 
canthus,  and  are  distributed  one  to  each  eyelid. 

j.  The  Front'al  artery,5  one  of  the  terminal  branches  of  the  ophthal- 
mic, passes  from  the  orbit  at  the  inner  canthus  and  ascends  upon  the 
forehead  beneath  the  muscles,  to  which  and  the  skin  it  is  distributed. 

k.  The  Na'sal  artery,6  the  remaining  branch  of  the  ophthalmic,  passes 
from  the  orbit  above  the  internal  palpebral  ligament,  and  descends  upon 
the  bridge  of  the  nose,  where  it  anastomoses  with  the  angular  artery. 

2.  The  Posterior  Communicating  "artery7  is  a  small  branch  of  the 
internal  carotid  proceeding  backward  at  the  side  of  the  infundibulum  to 
join  the  posterior  cerebral  artery. 

3.  The  Cho'roid  artery,8  the  smallest  branch  of  the  internal  carotid, 
ascends  on  the  outer  side  of  the  cerebral  crus,  and  enters  the  descending 
horn  of  the  lateral  ventricle  to  be  distributed  to  the  choroid  plexus. 

4.  The  Anterior  Cer'ebral  artery,9  a  terminal  branch  of  the  internal 
carotid,  ascends  the  longitudinal  fissure  of  the  cerebrum,  across  which  it 
is  connected  with  the  corresponding  artery  of  the  other  side,  by  a  trunk 
not  more  than  a  line  or  two  long,  called  the  anterior  communicating 
artery.10     It  then  turns  over  the  front  of  the  corpus  callosum,  and  runs 
backward  between  this  and  the  cerebral  hemisphere,  in  its  course  giving 
off  numerous  branches,  and  anastomosing  with  the  posterior  cerebral 
artery. 

5.  The  Middle  Cer'ebral  artery,11  the  remaining  branch  of  the  internal 
carotid,  ascends  the  fissure  separating  the  anterior  and  middle  cerebral 
lobes,  and  divides  into  branches  which  supply  the  latter. 

1  A.  ethmoidalis  anterior.  6  A.  nasalis ;  a.  dorsalis  nasi. 

2  A.  meningea  anterior.  7    A.   communicans    posterior ;    a.  c. 

3  A.  nasalis  anterior.  Willisii. 

4  A.  palpebrales  ;  a.  palpebralis  inter-          s  A.  choroidea. 

na  superior  et  inferior.    These  form  with  9  A.  cerebri  anterior ;   a.  corporis  cal- 

the  palpebral  branches  of  the  lachrymal  losi. 

artery  the  arcus  tarseus  superior  and  in-  10  A.  communicans  anterior. 

ferior.  n  A.  cerebri  media;  a.  c.  transversa;  a. 

5  A.  frontalis  ;  a.  supra- orbitalis.  fossae  Sylvii ;  a.  Sylviana. 


THE   VASCULAR   SYSTEM.  367 


THE  SUBCLAVIAN  ARTERIES. 

The  Right  Subcla'vian  artery1  springs  from  the  innominate  artery, 
and  curves  outwardly  to  the  interval  of  the  anterior  and  middle  scalene 
muscles,  between  which  it  passes  over  the  first  rib  and  assumes  the  name 
of  axillary  artery.  It  commences  opposite  the  right  sterno-clavicular 
articulation ;  and  is  in  relation  in  front  with  the  union  of  the  internal 
jugular  and  subclavian  veins,  and  is  crossed  in  the  same  position  by  the 
pneumogastric  nerve.  Behind  and  above  it  are  the  brachial  plexus  and 
the  great  sympathetic  nerve. 

The  Left  Subcla'vian  artery2  is  the  third  vessel  arising  in  succession 
from  the  summit  of  the  aortic  arch.  In  consequence  of  its  direct  origin 
from  the  latter,  it  is  longer  than  the  right  subclavian,  and  is  also  more 
deeply  situated.  It  ascends  vertically  to  a  distance  equal  with  the  length 
of  the  innominate  artery,  and  then  pursues  a  similar  course  to  the  right 
subclavian.  Its  ascending  portion  is  in  relation  with  the  left  common 
carotid  and  the  trachea  on  its  right ;  and  it  has  the  pneumogastric  nerve 
in  front. 

In  the  rare  cases  in  which  the  innominate  artery  is  represented  by  its 
ordinary  divisions,  the  right  subclavian  commonly  springs  from  the  arch 
of  the  aorta  after  all  the  other  branches,  and  reaches  its  usual  destina- 
tion by  passing  to  the  right  side  between  the  oesophagus  and  the  cervi- 
cal vertebrae. 

No  branches  are  given  off  by  the  ascending  portion  of  the  left  subcla- 
vian artery,  but  in  the  subsequent  part  of  its  course,  as  in  the  case  of 
the  right  subclavian,  the  following  arise  :— 

—•  1.  Vertebral  artery. 

2.  Thyroid  axis. 

4-3.  Inferior  thyroid  artery. 

•   4.  Supra-scapular  artery. 

5.  Transverse  cervical  artery. 

6.  Ascending  cervical  artery. 

7.  Internal  mammary  artery. 

8.  Superior  intercostal  artery. 

1.  The  Vertebral  artery,3  the  largest  branch  of  the  subclavian, 
passes  behind  the  common  carotid  artery,  and  enters  the  foramen  in  the 
transverse  process  of  the  sixth  cervical ,  vertebra.  Ascending  through 

1  A.  subclavia  dextra.  2  A.  subclavia  sinistra. 

3  A.  vertebralis ;  posterior  cerebral  artery. 


368  THE  VASCULAR  SYSTEM. 

the  foramina  of  the  other  transverse  processes,  it  winds  backward  around 
the  upper  articular  process  of  the  atlas,  perforates  the  dura  mater,  and 
enters  the  cranium  through  the  occipital  foramen.  It  then  proceeds  up- 
ward and  forward,  turns  around  the  side  of  the  medulla  oblongata,  and 
converges  to  join  its  fellow  at  the  lower  border  of  the  pons,  forming  by 
this  conjunction  the  basilar  artery.  Occasionally  the  vertebral  artery 
arises  directly  from  the  arch  of  the  aorta,  especially  the  left  one. 
The  branches  of  the  vertebral  artery  are  as  follow  : — 

a.  Muscular  branches. 

b.  Spinal  branches. 

c.  Posterior  meningeal  artery. 

d.  Posterior  spinal  artery. 

e.  Anterior  spinal  artery. 

/.  Inferior  cerebellar  arteries. 

a.  The  Muscular  branches,1  derived  from  the  vertebral  artery  in  the 
neck,  are  small  vessels  which  supply  the  muscles  attached  to  the  cervical 
transverse  processes, 

6.  The  Spinal  branches,2  also  derived  from  the  vertebral  artery  in  the 
neck,  are  small  vessels  which  pass  through  the  neighboring  intervertebral 
foramina  to  supply  the  spinal  cord  and  its  membranes. 

c.  The  Posterior  menin'geal  artery3  is  given  off  between  the  atlas 
and  occipital  foramen,  and  passes  through  the  latter  to  the  dura  mater 
of  the  cerebellar  fossa. 

d.  The  Posterior  spi'nal  artery,4  the  first  branch  of  the  vertebral 
within  the  cranium,  descends  on  the  posterior  surface  of  the  spinal  cord, 
anastomosing  in  its  course  with  the  spinal  branches  derived  from  the 
vertebral  artery  in  the  neck. 

e.  The  Inferior  cerebellar  arteries,5  usually  two  in  number,  wind 
around  the  upper  part  of  the  medulla  oblongata  to  the  under  surface  of 
the  cerebellum,  to  which  they  are  distributed. 

/.  The  Anterior  spi'nal  artery,6  the  last  branch  of  the  vertebral, 
unites  with  its  fellow  of  the  opposite  side  in  front  of  the  medulla 
oblongata,  and  the  common  vessel  thus  formed  descends  in  a  tortuous 
manner  in  front  of  the  spinal  cord,  to  which  it  is  distributed.  • 

The  Bas'ilar  artery,7  formed  by  the  union  of  the  two  vertebrals,  rests 

1  Rami  musculares.  posterior  and  anterior ;  inferior  cerebel- 

2  Rami  spinales.  lous  arteries. 

3  A.  meiringea  posterior.  6  A.  spinalis  anterior  ;  ant.  median  ar- 

4  A.  spinalis  posterior ;  posterior  me-  tery. 

dian  artery.  7  A.  basilaris ;    a.  cervicalis ;  a.  meso- 

6  A.  cerebelli  inferiores;  a.  c.  inferior      cephalica. 


THE  VASCULAR  SYSTEM.  369 

in  the  median  furrow  of  the  pons,  to  which  it  gives  small  branches, 
besides  sending  off  the  following  in  pairs  : — 

a.  Internal  auditory  arteries. 

b.  Superior  cerebellar  arteries. 
y?  c.  Posterior  uaMfcw44«r  arteries. 

a.  The  Internal  aud'itory  artery1  is  a  small  vessel  which  accompa- 
nies the  auditory  nerve  in  the  corresponding  meatus,  and  is  distributed, 
in  company  with  the  nerve,  to  the  labyrinth. 

b.  The  Superior  cerebel/lar  artery2  passes  outwardly  at  the  fore  part 
of  the  pons  to  the  upper  surface  of  the  cerebellum,  to  which  it  is  dis- 
tributed. 

c.  The  Posterior  cer'ebral  artery3  results  from  the  division  of  the 
basilar  artery.   Diverging  from  its  fellow  of  the  opposite  side,  it  receives 
the  posterior  communicating  artery  from  the  internal  carotid,  and  winds 
around  the  cerebral  crus  outward  and  backward  to  the  under  part  of  the 
posterior  lobe  of  the  cerebrum.     In  this  position  it  divides  into  many 
branches,  supplying  the  latter  and  anastomosing  with  the  other  cerebral 
arteries. 

In  the  early  part  of  its  course,  the  posterior  cerebral  artery  sends  a 
small  branch4  beneath  the  back  part  of  the  corpus  callosum  to  the  inter- 
posed velum  of  the  pia  mater  and  the  choroid  plexus. 

The  union  of  the  anterior  cerebral  arteries  by  the  anterior  communi- 
cating artery,  and  the  union  of  the  internal  carotids  with  the  posterior 
cerebrals  by  the  posterior  communicating  artery,  produce  together  an  ar- 
terial circle  at  the  base  of  the  brain,  around  the  position  of  the  pituitary 
fossa.  This  remarkable  series  of  anastomoses,  known  as  the  circle  of 
Willis,5  associates  the  circulating  currents  of  the  internal  carotid  and 
vertebral  arteries  in  such  a  manner  that  if  any  one  of  these  vessels 
becomes  obstructed,  those  remaining  are  still  able  to  convey  blood  to  all 
parts  of  the  brain. 

2.  The  Thy'roid  axis6  is  a  short,  thick  vessel  springing  from  the  fore 
part  of  the  subclavian  artery  near  the  anterior  scalene  muscle.  Imme- 
diately after  its  origin  it  divides  into  the  inferior  thyroid,  supra-scapular, 
transverse  cervical,  and  ascending  cervical  arteries.  Occasionally  another 

1  A.  auditiva  interna.  *  A.  choroidea  posterior. 

2  A.  cerebelli  superior ;  superior  cere-          5  Circulus  arteriosus  Willisii ;  arterial 
bellous  artery.  hexagon. 

3  A.  cerebri  posterior ;  a.  profunda  ce-          6  Truncus  thyro-cervicalis ;  a.  thyroi- 
rebri ;  a.  cerebri  inferior.  dea  inferior 

24 


370  THE   VASCULAR   SYSTEM. 

branch  comes  from  the  axis ;  and  any  of  the  branches  indicated  may 
arise  independently  from  the  subclavian  artery. 

3.  The  Inferior  Thy'roid  artery1  ascends  obliquely  behind  the  com- 
mon carotid  to  the  lower  part  of  the  thyroid  body,  to  which  it  is  distrib- 
uted, anastomosing  freely  with  the  superior  thyroid.     It  likewise  gives 
small  branches  to  the  trachea,  larynx,  and  oesophagus. 

4.  The  Supra-scap'ular  artery2  passes  outwardly  behind  the  clavicle 
and  between  the  sterno-mastoid  and  scalene  muscles  to  the  upper  border 
of  the  scapula,  over  which  it  turns  to  the  supra-spinous  fossa.     In  this 
it  lies  close  to  the  bone,  and  is  chiefly  spent  on  the  supra-spinous  muscle. 
In  its  course  it  gives  a  small  branch3  to  the  subcutaneous  surface  of  the 
acromion ;  and  a  larger  branch  descends  behind  the  neck  of  the  scapula 
to  the  infra-spinous  muscle. 

Occasionally  the  supra-scapular  comes  directly  from  the  subclavian 
artery,  or  from  some  of  its  other  branches  ;  and  sometimes  it  arises  from 
the  axillary  artery. 

5.  The  Transverse  Cer'vical  artery4  passes  outwardly  above  and  par- 
allel to  the  preceding,  and  crosses  the  scalene  muscles  and   brachial 
plexus  of  nerves  beneath  the  trapezius  muscle  to  the  upper  angle  of  the 
scapula.     Occasionally  it  is  a  branch  directly  of  the  subclavian  artery ; 
and  it  divides  into  the  following  branches  : — 

a.  Superior  cervical  artery. 

b.  Posterior  scapular  artery. 

a.  The  Superficial  cer'vical  artery,5  often  a  branch  of  the  ascending 
cervical,  passes  upwardly  beneath  the  outer  border  of  the  trapezius 
muscle,  and  supplies  this,  the  elevator  of  the  scapular  angle,  the  sterno- 
mastoid  muscle,  the  contiguous  lymphatic  glands,  and  the  skin. 

6.  The  Posterior  scap'ular  artery6  descends  along  the  base  of  the 
scapula  under  the  rhomboid  muscle,  and  supplies  this,  the  great  serrated, 
and  latissimus  muscles,  and  anastomoses  with  the  supra-  and  subscapular 
arteries. 


1  A.  thyroidea  inferior ;    ramus  thy-          4  A.  transversa   cervicis,  or  colli ;   a. 
reoideae  thyroideus.  cervico-scapularis. 

2  A.  supra-scapularis  ;    a.  transversa          5  A.  superficialis  cervicis ;  a.  cervicalis 
scapulae  ;  ramus  transversus  scapularis.  posterior. 

3  Ramus  acromialis ;  r.  supra-acromi-          6  A.  scapularis  posterioris ;  a.  dorsalis 
alis.  scapulae. 


THE  VASCULAR  SYSTEM.  371 

6.  The  Ascending  Cer'vical  artery,1  a  small  vessel  derived  from  the 
thyroid  axis,  or  the  inferior  thyroid  artery,  or  less  frequently  from  one 
of  the  other  branches  of  the  subclavian,  passes  up  the  neck  in  front  of  the 
origin  of  the  scalene  muscles,  to  which,  and  other  contiguous  muscles, 
and  the  lymphatic  glands,  it  is  distributed. 

Y.  The  Internal  Mam'mary  artery2  is  given  from  the  subclavian,  op- 
posite the  thyroid  axis.  It  descends  behind  the  clavicle  and  costal  car- 
tilages, a  short  distance  from  the  sternum,  and  near  the  lower  end  of  the 
latter  divides  into  the  musculo-phrenic  and  superior  epigastric  arteries. 
The  branches  derived  from  this  vessel  in  its  course,  together  with  the 
terminal  ones,  are  as  follow : — 

a.  Mediastinal  arteries. 

b.  Superior  phrenic  arteries. 

c.  Perforating  arteries. 

d.  Anterior  intercostal  arteries. 

e.  Musculo-phrenic  artery. 
/.  Superior  epigastric  artery. 

a.  The  Medias'tinal  arteries3  are  minute  branches  supplying  the  parts 
of  the  anterior  mediastinal  space,  including  the  thymus  gland,  bronchus, 
pericardium,  pleura,  sterno-costal  muscle,  and  sternum. 

b.  The  Superior  phrenic  artery*  is  a  thread-like  vessel  descending  in 
company  with  the  phrenic  nerve  to  the  diaphragm. 

c.  The  Perforating  arteries5  consist  of  five  or  six  small  vessels  per- 
forating the  corresponding  upper  intercostal  spaces  near  the  sternum,  to 
supply  the  origin  of  the  great  pectoral  muscle  and  the  contiguous  skin. 
In  the  female,  the  intermediate  three  or  four  vessels  are  larger  than  in 
the  male,  and  contribute  to  supply  the  mammary  gland.     During  lacta- 
tion they  increase  in  size. 

d.  The  Anterior  intercostal  arteries,6  usually  two  in  each  intercostal 
space,  arise  together  from  the  mammary,  or  separately,  or  in  common 
with  the  perforating  arteries.     Proceeding  outwardly  in  the  upper  five 
or  six  intercostal  spaces,  they  anastomose  with  the  aortic  intercostal 
arteries,  and  supply  the  intercostal  and  pectoral  muscles,  the  mammary 
gland,  and  the  skin. 

1  A.  cervicalis  ascendens ;  a.  c.  ante-      chialis   anterior,  pericardiacae,  et  ster- 
rior :  a.  dorsalis  suprema ;    ramus  thy-      nales. 

roideae  ascendens.  *  A.  phrenica  superior ;   a.  pericardia- 

2  A.  mammaria  interna ;  a.  sternalis  ;       co-phrenica. 

a.  substernalis ;  a.  thoracica  interna.  5  A.  perforantes  et  mammarise  exter- 

3  A.  mediastinicee  ;   a.  thymicee,  bron-      nse  ;  mammary  arteries. 

6  A.  intercostales  anteriores. 


372  THE   VASCULAR  SYSTEM. 

e.  The  Mus'culo-phren'ic  artery,1  the  outer  of  the  terminal  pair  of 
branches  of  the  mammary  artery,  inclines  downward  and  outward  behind 
the  costal  cartilages  of  the  lower  ribs  to  the  last  intercostal  space.  In 
its  course  it  gives  branches  to  the  lower  five  intercostal  spaces  and  to  the 
attachments  of  the  diaphragm  and  abdominal  muscles. 

/.  The  Superior  epigastric  artery2  continues  in  the  direction  of  the 
mammary  artery  to  the  abdominal  parietes  back  of  the  straight  muscle, 
to  which  it  is  mainly  distributed,  anastomosing  also  with  the  epigastric 
branch  of  the  external  iliac  artery,  and  with  others  supplying  the  abdom- 
inal walls. 

8.  The  Superior  Intercos'tal  artery3  arises  from  the  back  part  of  the 
subclavian,  descends  in  front  of  the  neck  of  the  first  rib,  and  divides  into 
two  branches,  which  supply  the  first  pair  of  intercostal  spaces. 

9.  The  Profound  Cer'vical  artery,4  frequently  originating  in  common 
with  the  preceding  vessel,  penetrates  beneath  the  transverse  process  of 
the  last  cervical  vertebra  to  the  back  of  the  neck,  where  it  ascends 
between  the  transverse  and  spinous  processes  to  supply  the  contiguous 
muscles. 

THE  AXILLARY  ARTERY. 

The  Ax'illary  artery5  is  the  continuation  of  the  subclavian  from  the 
outer  border  of  the  first  rib  to  the  lower  margin  of  the  axilla,  after 
which  it  assumes  the  name  of  brachial  artery.  In  its  course  through  the 
armpit  it  rests  on  the  great  serrated,  subscapular,  latissimus,  and  greater 
terete  muscles,  and  is  under  cover  of  the  pectoral  muscles.  In  front  of  it 
is  the  axillary  vein ;  and  the  brachial  plexus  at  first  is  behind,  and  after- 
wards surrounds  it. 

The  most  important  deviation  from  the  ordinary  arrangement  of  the 
axillary  artery  consists  in  its  giving  off  a  large  branch,  which  corresponds 
with  the  radial  artery  of  the  forearm,  or  less  frequently  with  the  ulnar 
artery,  or  rarely  with  the  interosseous  artery.  In  some  instances  the 
large  branch  is  the  common  source  of  several  or  all  of  the  smaller  ones, 
commonly  derived  separately  from  the  axillary  and  brachial  arteries. 

Besides  several  small  and  inconstant  twigs6  to  the  contiguous  muscles 

1  A.  musculo-phrenica.  posterior  ;  a.  trans versalis  colli ;  a.  tra- 

2  A.  epigastrica  superior.  chelo-cervicalis. 

3  A.  intercostalis  superior,  or  supre-          5  A.  axillaris. 

ma ;  a.  i.  subclavia.  6  Muscular  branches  and  axillary  tho- 

4  A.  profunda  cervicis ;    a.  cervicalis      racic  artery ;   a.  thoracica   axillaris,  or 

alaris ;  a.  ultima  thoracicarum. 


THE   VASCULAR   SYSTEM. 


373 


FIG.  254. 


and  lymphatic  glands  of  the  armpit,  the  axillary  artery  usually  gives  off 
in  succession  the  following  branches : — 

1.  Superior  thoracic  artery. 

2.  Acromial  thoracic  artery. 

3.  Long  thoracic  artery. 

4.  Subscapular  artery. 

5.  Anterior  circumflex  artery. 

6.  Posterior  circumflex  artery. 

1.  The  Superior  Thorac'ic   artery,1  sometimes  substituted  by  two 
branches,  and  frequently 

arising  in  common  with 
the  succeeding  artery, 
passes  between  the  sub- 
clavian  and  small  pectoral 
muscles  to  supply  the  lat- 
ter, the  great  pectoral 
muscle,  and  the  mammary 
gland. 

2.  The  Acro'mial  Tho- 
rac'ic artery2  ascends  to 
the  space  above  the  small 
pectoral  muscle,  and  di- 
vides into  branches,  which 
supply  the  pectoral  and 
deltoid  muscles,  the  shoul- 
der joint,  and  the  subcu- 
taneous   surface    of    the 
acromion.     In  the  latter 


VIEW  OF  THE  AXILLARY  ARTERY,  portions  of  the  pectoral  and  del- 
toid muscles  removed.  1,  axillary  artery ;  2,  superior  thoracic ; 
3,  acromial  thoracic;  4,  long  thoracic;  5,  subscapular;  6,  anterior 


position     it     anastomoses     circumflex ;  7,  posterior  circumflex;  8,  brachial  artery ;  9,  superior 

with  branches  of  the  su-    profound  artery" 

pra-scapular  artery,  forming  together  a  fine  vascular  net.3 

3.  The  Long  Thorac'ic  artery4  descends  along  the  small  pectoral 
muscle,  and  is  distributed  to  the  mammary  gland,  both  pectoral,  and  the 
great  serrated  muscles. 


1  A.  thoracica  superior;  a.  t.  externa 
superior ;  first  thoracic  artery. 

2  A.  thoracica  acromialis ;  a.  t.  hume- 
ralis ;  a.  acromialis  ;  external  scapular, 
or  third  thoracic  artery. 


3  Rete  acromiale. 

4  A.  thoracica  longa  ;  a.  t.  inferior ;  a. 
t.  externa  inferior;  a.  mammaria  exter- 
na ;  second  thoracic  artery. 


\ 


374  THE  VASCULAR  SYSTEM. 

4.  The  Subscap'ular  artery,1  the  largest  branch  of  the  axillary,  de- 
scends along  the  outer  border  of  the  scapula,  and  is  distributed  to  the 
subscapular,  great  serrated,  greater  terete,  and  latissimus  muscles.     In 
its  course  it  gives  off  a  large  branch,  as.  follows : — 

a.  The  Dorsal  scap'ular  artery.2 — This  passes  between  the  greater 
terete  and  subscapular  muscles  around  the  outer  border  of  the  scapula 
to  the  infra-spinous  fossa,  to  the  muscle  of  which  it  is  distributed,  and 
anastomoses  with  the  supra-  and  posterior  scapular  arteries. 

5.  The  Anterior  Circum'flex  artery3  is  a  small  branch  winding  for- 
ward and  outward  around  the  humerus  below  its  tuberosities,  supplying 
the  shoulder  joint  and  inosculating  with  the  succeeding  artery. 

6.  The  Posterior  Circum/flex  artery,4  much  larger  than  the  preceding, 
turns  backward  between  the  triceps  extensor  and  the  humerus  to  the 
deltoid  muscle,  which  it  supplies,  also  giving  branches  to  the  shoulder 
joint,  and  anastomosing  with  the  anterior  circumflex,  the  supra-scapular, 
and  acromial  thoracic  arteries. 

THE  BEACHIAL  ARTERY. 

The  Bra'chial  artery,5  the  continuation  of  the  axillary,  extends  from 
the  outer  border  of  the  axilla  along  the  inner  side  of  the  arm.  It  com- 
mences opposite  the  tendons  of  insertion  of  the  latissimus  and  greater 
terete  muscles,  and,  about  a  finger's-breadth  below  the  bend  of  the  elbow 
joint,  divides  into  the  radial  and  ulnar  arteries.  In  its  course  it  lies  on 
the  coraco-brachial,  triceps  extensor,  and  brachial  muscles.  The  median 
nerve  is  at  first  on  its  outer  side,  and  then  crosses  in  front  to  its  inner 
side.  The  ulnar  nerve  is  in  the  latter  position,  but  gradually  diverges  in 
approaching  the  elbow. 

The  brachial  artery  is  accompanied  by  two  companion  veins,  which  lie 
in  close  contact  with  it;  and  the  basilic  vein  is  placed  over  it.  In  nearly 
its  whole  length  it  is  only  covered  by  the  brachial  fascia  and  skin,  and  in 
an  operation  may  readily  be  exposed  without  cutting  the  neighboring 
muscles.  In  front  of  the  elbow  joint  it  dips  between  the  terete  pronator 
and  long  supinator,  and  is  covered  by  the  offset  from  the  tendon  of 
the  biceps  flexor  to  the  fascia  of  the  forearm. 

1  A.  subscapularis  ;  a.  scapularis  infe-  3  A.  circumflexa  anterior;  a.  articula- 
rior;  a.  s.  communis ;  a.  s.  interims ;   a.       ris  anterior. 

thoracica  axillaris,  or  alaris.  4  A.  circumflexa  posterior;  a.  articu- 

2  A.  dorsalis  scapulae  ;  a.  circumflexa      laris  posterior. 

scapulae.  5  A.  brachialis  ;  a.  humeralis. 


THE   VASCULAR   SYSTEM. 


375 


FIG.  255. 


As  an  important  variation  from  the  ordinary  arrangement  of  the 
brachial  artery,  it  may  divide  into  its  two  principal  branches  in  any  posi- 
tion along  the  arm. 

The  number  of  branches  of  the 
brachial  artery  and  the  order  of 
their  succession  is  variable,  but 
usually  they  will  be  found  to  ac- 
cord with  the  following  series : — 

1.  Superior  profound  artery. 

2.  Inferior  profound  artery. 

3.  Medullary  artery. 

4.  Muscular  arteries. 

5.  Anastomotic  artery. 

6.  Radial  artery. 

7.  Ulnar  artery. 

1.  The  Superior  Profound  ar- 
tery,1 the  largest  branch  of  the 
brachial  except  its  ultimate  divi- 
sions, accompanies  the  musculo- 
spiral  nerve  between  the  triceps 
extensor  and  the  humerus  to  the 
outer  part  of  the  arm,  where  it  de- 
scends between  the  long  supinator 
and  brachial  muscle  to  the  elbow. 
In  its  course  it  supplies  the  coraco- 
brachial,  triceps  extensor,  brachial, 
and  long  supinator  muscles,  and  at 
the  elbow  anastomoses  with  the 
radial,  interosseous  and  ulnar  re- 
current, the  inferior  profound,  and 
anastomotic  arteries. 


18  <¥ 


VIEW  OF   THE  AXILLARY   AND  BRACHIAL    ARTERY. 

portions  of  the  pectoral  and  deltoid  muscles  re- 
moved. 1,  axillary  artery ;  2,  brachial  artery ;  3, 
superior  thoracic  artery ;  4,  acromial  thoracic ;  5, 
long  thoracic ;  6,  subscapular ;  7,  anterior  circum- 
flex; 8,  posterior  circumflex;  9,  superior  profound, 
the  first  branch  of  the  brachial  artery ;  10,  inferior 
profound ;  11,  anastomotic ;  12,  radial ;  13,  ulnar  : 
14,  interosseous;  15,  recurrent  radial;  16,  recurrent 
ulnar  artery. 


2.  The  Inferior  Profound  ar- 
tery,2 a  small  vessel  from  near  the 
middle  of  the  brachial,  descends  along  the  inner  side  of  the  triceps  ex- 
tensor, in  company  with  the  ulnar  nerve,  to  the  interval  of  the  internal 
condyle  and  olecranon.  It  supplies  the  brachial  muscle,  and  anastomoses 
with  the  ulnar  recurrent  and  anastomotic  arteries. 


1  A.  profunda  superior ;  a.  p.  major 
humeri ;  a.  p.  brachii ;  a.  collateralis 
magna ;  a.  c.  externa ;  a.  spiralis ;  great 
muscular  artery  of  the  arm. 


2  A.  profunda  inferior;  a.  p.  minor  : 
a.  collateralis  prima;  a.  c.  superior: 
large  communicating  ulnar  artery  ;  pro- 
funda-ulnar  artery. 


376  THE   VASCULAR  SYSTEM. 

3.  The  Med'ullary  artery,1  a  small  vessel  from  near  the  middle  of  the 
brachial,  or  from  one  of  its  other  branches,  proceeds  through  the  medul- 
lary foramen  of  the  humerus  to  the  marrow,  which  it  supplies. 

4.  The  Muscular  arteries2  consist  of  several  small  branches  to  the 
coraco-brachial,  biceps  flexor,  triceps  extensor,  and  brachial  muscles. 

5.  The  Anastomot'ic  artery,3  from  the  lower  part  of  the  brachial, 
descends  to  the  internal  condyle,  and  there  anastomoses  with  the  ulnar 
recurrent  and  profound  arteries. 

The  anastomotic  and  profound  branches  of  the  brachial  artery  form, 
with  the  recurrent  branches  of  the  radial,  ulnar,  and  interosseous  arteries, 
a  fine  vascular  net,4  which  envelops  and  supplies  the  elbow  joint  and 
the  spongy  extremities  of  the  bones. 

THE  EADIAL  ARTERY. 

The  Ra'dial  artery,5  the  smaller  of  the  ultimate  divisions  of  the  bra- 
chial, from  its  direction  appears  as  if  it  were  a  continuation  of  the  latter. 
It  proceeds  along  the  outer  side  of  the  front  of  the  forearm,  between  the 
long  supinator  and  radio-carpal  flexor  to  the  lower  end  of  the  radius. 
It  then  turns  around  the  outer  side  of  the  wrist  beneath  the  extensor 
tendons  of  the  thumb,  to  the  back  of  the  carpus,  where,  reaching  the 
interval  of  the  first  pair  of  metacarpal  bones,  it  penetrates  to  the  palm 
of  the  hand,  and  ends  in  the  deep  palmar  arch. 

In  the  early  part  of  its  course  it  rests  on  the  tendon  of  the  biceps 
flexor  and  the  insertion  of  the  round  pronator,  and  is  overlapped  by  the 
fleshy  part  of  the  long  supinator.  Subsequently  it  rests  on  the  long 
flexor  of  the  thumb,  the  quadrate  pronator,  and  the  radius,  and  is 
covered  alone  by  the  fascia  and  skin.  Near  the  wrist,  during  life,  this 
artery  is  found  very  convenient,  to  determine  the  condition  of  the  circu- 
lation as  indicated  by  the  pulse.  It  is  accompanied  by  a  pair  of  com- 
panion veins,  and  part  of  the  way  by  the  radial  nerve. 

In  those  cases  in  which  the  radial  artery  is  derived  from  the  brachial 
above  its  ordinary  source,  it  passes  along  the  inner  side  of  the  latter,  and 
then  crosses  to  its  outer  side.  Reaching  the  elbow,  it  usually  pierces  the 
brachial  fascia,  and  proceeds  between  it  and  the  skin  down  the  outer 

1  A.  nutritia  humeri.  cus  magnus ;  a.  collateralis  interims ;  a. 

'l  Kami  musculares.  c.  ulnaris  secunda ;  a.  c.  u.  inferior. 

3  A.  anastomotica ;  ramus  anastomoti-          4  Rete  articulare  cubiti. 

5  A.  radialis  ;  a.  externa  cubiti. 


THE   VASCULAR   SYSTEM. 


377 


FIG.  256. 


side  of  the  forearm ;  or,  less  frequently,  from  the  position  of  the  elbow  it 
pursues  the  ordinary  course. 

The  branches  of  the  radial  artery  are  as 
follow : — 

1.  Radial  recurrent  artery. 

2.  Muscular  branches. 

3.  Anterior  carpal  artery. 

4.  Yolar  artery. 

5.  Posterior  carpal  artery. 

6.  Metacarpal  artery. 

7.  Principal  artery  of  the  thumb. 

8.  Radial  index  artery. 

9.  Deep  palmar  arch. 

1.  The  Ra'dial  Recur/rent  artery,1  derived 
from  near  the  commencement  of  the  radial, 
ascends  between  the  long  and  short  supinators 
to  the  external  condyle.     It  supplies  the  con- 
tiguous parts  of  the  supinator  and  extensor 
muscles,   and   anastomoses  with  the  superior 
profound  artery. 

2.  The  Muscular  branches  are  small  vessels 
given  to  the  neighboring  muscles  in  the  course 
of  the  radial  artery. 

3.  The  Anterior  Car'pal  artery2  is  a  small 
branch  from  the  lower  part  of  the  radial,  de- 
scending to  the  front  of  the  radio-carpal  artic- 
ulation, where  it  forms  an  anastomosis3  with  a 
similar  branch  from  the  ulnar  artery,  and  sup- 
plies the  wrist  joint. 


ARTERIES  OF  THE  FOREARM.  2, 
brachial  artery ;  3,  anastomotic  ar- 
tery ;  4,  radial  artery ;  5,  ulnar  ar- 
tery ;  6,  recurrent  ulnar ;  7,  inter- 
osseous  ;  8,  anterior  carpal ;  9,  su- 
perficial volar;  10,  anterior  carpal 

4.  The  Volar  artery/  very  variable  in  its    branch  of  the  uinar;ii,  superficial 
size  and  arrangement,  is  usually  a  small  vessel 
derived  from  the  radial  just  before  it  turns  to 
the  back  of  the  carpus.     Descending  in  front 
of  the  ball  of  the  thumb,  it  supplies  the  small  muscles  of  the  latter,  and 
contributes  to  form  the  superficial  palmar  arch. 


palmar  arch ;  12,  principal  artery 
of  the  thumb ;  13,  radial  index  ar- 
tery; 14,  digital  arteries;  15,  re- 
current branches. 


1  A.  recurrens  radialis ;  recurrent  ar- 
tery of  the  epicondyle. 

2  A.  carpea  anterior ;  a.  c.  volaris  ;  a. 
radio-carpalis  ;  a.  transversa- carpi  ante- 
rior. 


3  Anterior   carpal   arch ;    rete   carpi 
volare. 

4  A  superficialis  volse  :  superficial  vo- 
lar artery  ;  ramus  volaris  ;  a.  radio-pal- 
maris ;  external  superficial  artery  of  the 
palm. 


378  THE  VASCULAR  SYSTEM. 

5.  The  Posterior  Car'pal  artery1  is  a  small  branch  from  the  posterior 
portion  of  the  radial,  which  crosses  the  back  of  the  carpus  beneath  the 
extensor  tendons,  to  join  with  a  similar  branch  of  the  ulnar  artery. 
From  this  conjunction2  twigs  supply  the  wrist  joint ;  and  branches3  pro- 
ceed to  the  outer  three  metacarpal  interspaces,  each  dividing  into  a  pair,* 
which  descend  along  the  contiguous  sides  of  the  backs  of  the  fingers. 

6.  The  Metacar'pal  artery5  is  a  small  vessel  descending  upon  the 
first  metacarpal  interspace,  and  dividing  into  three  branches,6  which  pro- 
ceed along  the  sides  of  the  thumb  and  the  approximate  side  of  the 
index  finger. 

7.  The  Principal  artery  of  the  Thumb7  is  derived  from  the  radial 
just  after  it  reaches  the  palm  of  the  hand.     It  descends  along  the  first 
metacarpal  bone,  and  divides  into  two  digital  arteries,8  which  proceed 
along  the  opposite  sides  of  the  thumb  to  its  extremity. 

8.  The   Ra'dial  Index   artery9  arises  close  to  the  preceding  and 
descends  along  the  radial  border  of  the  index  finger  to  its  extremity. 

9.  The  Deep  Pal'mar  Arch10  is  formed  by  the  conjunction  of  the  termi- 
nating portion  of  the  radial  with  the  communicating  artery  from  the 
ulnar.     It  lies  transversely  across  the  upper  part  of  the  metacarpus, 
beneath  the  flexor  tendons,  and  gives  off  the  following  branches : — 

a.  Recurrent  branches. 

b.  Perforating  branches. 

c.  Interosseous  arteries. 

a.  The  Recurrent  branches11  ascend  and  anastomose  with  the  anterior 
carpal  arteries. 

b.  The  Perforating  branches12  pass  through  the  upper  part  of  the  in- 
terosseous  spaces  and  join  the  branches  of  the  posterior  carpal  arteries. 

c.  The  Interos'seous  arteries13  supply  the  corresponding  muscles,  and 
anastomose  with  the  digital  branches  of  the  superficial  palmar  arch. 

1  A.  carpse  posterior ;  a.  c.  dorsalis ;  a.  8  A.  volaris  pollicis  radialis  and  ulna- 
transversa    carpi-dorsalis ;    a.    dorsalis      ris. 

carpi-radialis.  9  A.  radialis  indicis  ;  a.  volaris  indicis 

2  Posterior   carpal  arch ;    rete    carpi      radialis. 

dorsale ;  r.  carpeum  posterius.  10  Arcus  palmaris  profundus  ;  a.  vola- 

3  A.  interossese  dorsales.  ris  profundus ;  profound,  or  radial  pal- 

4  A.  digitales  dorsales.  mar  arch. 

5  A.  interossese  dorsalis  prima.  n  Kami  recurrentes ;  r.  retrogradi. 

6  A.  dorsalis  pollicis  et  indicis ;  a.  dor-  12  Kami  interossei  perforantes ;  r.  per- 
salis  pcllicis  radialis  et  ulnaris,  et  indi-  forantes  superiores. 

cis  radialis.  13  A.  interossese  volares. 

7  A.  princeps  pollicis ;  a.  magna  polli- 
cis ;  a.  pollicaris. 


THE  VASCULAR  SYSTEM.  379 


THE  ULNAE  ARTERY. 

The  TJl'nar  artery,1  the  second  division  of  the  brachial,  turns  inwardly 
beneath  the  muscles  springing  from  the  internal  condyle,  and  descends 
on  the  inner  side  of  the  forearm  between  the  ulno-carpal  and  superficial 
flexor  of  the  fingers  to  the  wrist.  Passing  over  the  anterior  annular  liga- 
ment at  the  side  of  the  pisiform  bone  to  the  palm  of  the  hand,  it  termin- 
ates in  the  formation  of  the  superficial  palmar  arch.  In  the  early  part  of 
its  course  it  rests  on  the  insertion  of  the  brachial  muscle,  and  afterwards 
on  the  deep  flexor  of  the  fingers.  It  is  accompanied  by  two  companion 
veins,  and  in  the  greater  part  of  its  course  by  the  ulnar  nerve. 

In  those  anomalous  instances  in  which  the  ulnar  artery  comes  from  the 
brachial  above  its  ordinary  position,  as  it  approaches  the  elbow  it  in- 
clines inwardly,  and  passes  over  the  heads  of  the  flexor  muscles  instead 
of  beneath  them,  and  then  pursues  the  usual  course  down  the  forearm. 

The  branches  given  from  the  ulnar  artery  are  as  follow  : — 

1.  Ulnar  recurrent  artery. 

2.  Common  interosseous  artery. 

3.  Muscular  branches. 

4.  Posterior  carpal  artery. 

5.  Anterior  carpal  artery. 

6.  Communicating  artery. 

7.  Superficial  palmar  arch. 

1.  The  Ulnar  Recurrent  artery,2  frequently  substituted  by  a  pair  of 
branches,  comes  from  the  ulnar  just  below  the  elbow,  and  ascends  beneath 
the  muscles  arising  from  the  internal  condyle.     It  supplies  the  heads  of 
the  flexor  muscles,  and  anastomoses  with  the  inferior  profound,  anasto- 
motic,  and  other  arteries  about  the  elbow  joint. 

2.  The  Common  Interos'seous  artery3  comes  from  the  ulnar  near  the 
tuberosity  of  the  radius,  and  shortly  afterwards  divides  into  the  anterior 
and  posterior  interosseous  arteries.    Occasionally  the  common  interosse- 
ous artery  is  a  branch  of  the  brachial ;  and  when  the  ulnar  artery  de- 
rives its  origin  above  the  usual  position,  the  common  interosseous  and 
radial  arteries  appear  as  the  terminal  divisions  of  the  brachial. 

a.  The  Anterior  interos'seous  artery*  descends  in  front  of  the  inter- 

1  A.  ulnaris;  cubital  artery;  a.  cubi-  3  A.  interossea  communis ;  a  interos- 
talis.  sea  antibrachii  communis ;  a.  interossea. 

2  A.  recurrens  ulnaris ;    a.  r.  u.  ante-  4  A.  interossea  anterior,  or  interna. 
rior  and  posterior ;  a.  r  epitrochleae  ;  a. 

r.  cubitalis  anterior  and  posterior. 


380  THE   VASCULAR   SYSTEM. 

osseous  membrane  as  far  as  the  quadrate  pronator,  when  it  pierces  the 
former  and  passes  to  the  back  of  the  wrist,  where  it  anastomoses  witli 
the  posterior  carpal  arteries.  In  its  course  it  gives  branches  to  the 
neighboring  muscles. 

6.  The  Posterior  interos'seous  artery1  passes  to  the  back  of  the  fore- 
arm through  the  opening  at  the  upper  part  of  the  interosseous  membrane, 
and  descends  beneath  the  common  extensor  of  the  fingers  to  the  wrist, 
supplying  in  its  course  the  contiguous  muscles,  and  anastomosing  with 
the  anterior  interosseous  and  posterior  carpal  arteries.  At  its  upper 
part  it  gives  off  the  Interosseous  recurrent  artery,2  which  ascends  be- 
neath the  short  supinator  and  anconeus  muscles  to  the  interval  of  the 
olecranon  and  external  condyle,  and  anastomoses  with  the  superior  pro- 
found and  radial  recurrent  arteries. 

3.  The  Muscular  branches  of  the  ulnar  artery  are  small  vessels  given 
to  the  neighboring  muscles. 

4.  The  Posterior  Car'pal  artery,3  of  variable  size,  comes  from  the 
lower  part  of  the  ulnar  artery  and  turns  beneath  the  tendon  of  the  ulno- 
carpal  flexor  to  the  back  of  the  wrist.     It  sends  a  metacarpal  branch  to 
the  inner  side  of  the  hand  and  little  finger,  and  terminates  by  joining 
the  corresponding  branch  of  the  radial  artery. 

5.  The  Anterior  Car'pal  artery,4  smaller  than  the  preceding,  passes 
outwardly  to  the  front  of  the  wrist,  where  it  joins  the  anterior  carpal 
branch  of  the  radial  artery. 

6.  The  Communicating  artery5  is  derived  from  the  ulnar  just  after 
passing  the-  pisiform  bone,  and  dips  between  the  short  flexor  and  abduc- 
tor of  the  little  finger  to  contribute  in  the  formation  of  the  deep  palmar 
arch. 

T.  The  Superficial  Palmar  arch,6  the  terminating  portion  of  the  ulnar 
artery,  curves  internally  in  the  palm  of  the  hand,  upon  the  flexor  tendons 
and  beneath  the  palmar  fascia,  and  joins  the  volar  artery  of  the  radial. 
The  branches  given  from  the  arch  are  four  digitals.7 


1  A.  interossea  posterior,  or  externa;  5  A.  communicans ;  a.  cubitalis  manus 
a.  perforans  suprema.  profunda. 

2  A.  interossea  recurrens ;  a.  recurrens  6  Arcus  palmaris  superficialis ;   arcus 
olecranea ;  a.  r.  radialis  posterior.  volaris  sublimis  ;  a.  v.  superficialis  ;  ra- 

3  A.  carpea  posterior;  ramus  dorsalis.  mus  volaris  superficialis. 

*  A.  carpea  anterior.  7  A.  digitales  volares ;  a.  d.  communes. 


THE   VASCULAR   SYSTEM. 


381 


FIG.  257. 


The  first  Digital  artery  runs  along  the  ulnar  side  of  the  hand  and  little 
finger  to  its  extremity. 
The  remaining  Dig'ital 
arteries  descend  along 
the  metacarpal  inter- 
spaces, except  the  first,  to 
the  roots  of  the  fingers, 
where  each  divides  into 
two  branches1  which  run 
along  the  contiguous  sides 
of  the  fingers  to  their  tips. 

The  arteries  of  the  hand 
exhibit  frequent  varia- 
tions in  their  arrange- 
ment. In  some  instances 
the  contribution  of  the  ul- 
nar artery  to  the  super- 
ficial arch  is  much  reduced, 
and  that  from  the  radial 
artery  is  in  a  correspond- 
ing degree  increased.  In 
other  instances  the  con- 
tributions of  both  are  re- 
duced, even  to  a  want  of 
continuity  in  the  super- 
ficial arch,  and  each  supplies  its  own  side  of  the  hand ;  or  the  deep  arch 
is  larger,  and  then  appears  mainly  to  supply  the  hand  and  fingers. 


ARTERIES  OP  THE  HAND;  PALMAR  SURFACE.  1,  radial  artery;  2, 
ulnar ;  3,  communicating  branch  with  the  deep  palmar  arch ;  4, 
superficial  palmar  arch;  5,  superficial  volar  artery;  6,  digital  ar- 
teries of  the  thumb;  7,  radial  index  artery;  8,  digital  artery  to 
the  little  finger;  9,  common  digital  arteries;  10,  digitals  to  the 
fingers. 


THOEACIC  AORTA. 

The  Thorac'ic  Aor'ta2  commences  with  the  termination  of  the  arch  of 
the  aorta  on  the  left  side  of  the  third  dorsal  vetrebra.  Descending  on 
the  left  of  the  vertebral  column,  in  the  lower  part  of  its  course  it  gradu- 
ally inclines  toward  the  median  line,  which 'it  nearly  reaches  opposite  the 
last  dorsal  vertebra,  arid  there  passes  through  the  aortic  orifice  of  the 
diaphragm  to  assume  the  name  of  abdominal  aorta.  It  is  situated  in 
the  posterior  mediastinal  space  behind  the  pericardium  and  the  root  of 
the  left  lung.  .  It  is  in  relation  on  the  right  with  the  oesophagus,  azygos 
vein,  and  thoracic  duct ;  on  the  left  with  the  corresponding  pleura  and 
lung. 


1  Collateral  digital  arteries. 


2  Aorta  thoracicus. 


382 


THE   VASCULAR   SYSTEM. 


J 


The  branches  of  the  thoracic  aorta  are  all  of  small  size,  and  come  off 

in  succession,  as  follow : — 

1.  Pericardiac  arteries. 

2.  Bronchial  arteries. 

3.  (Esophageal  arteries. 

4.  Mediastinal  arteries. 

5.  Intercostal  arteries. 

1.  The    Pericar'diac    arteries1 
consist  of  a  few  fine  vessels  rami- 
fying on  the  contiguous  portion  of 
the  pericardium. 

2.  The  Bron'chial  arteries,2  two 
or  three  in   number,  occasionally 
originating    in   one   trunk,    apply 
themselves  to  the  bronchi  and  ac- 
company them  in  their  ramification 
through  the  lungs.     Sometimes  the 
right   bronchial  artery  is  derived 
from  the  corresponding  third  inter- 
costal artery. 

3.  The  Oesophage'al  arteries,3 
four  or  five  in  number,  supply  the 
oesophagus. 

4.  The    Medias'tinal    arteries4 
consist  of  a  number  of  fine  ves- 
sels distributed  on  the  neighboring 
pleurae  and  lymphatic  glands. 

5.  The  Intercostal  arteries,5  of 
which  there  are  ten  on  each  side, 
including  the  one  below  the  last 
rib,  come  off  from  the  back  of  the 
aorta  opposite  the  vertebral  bodies. 
Those  of  the  left  side  are  shorter 
than  the  right  ones  in  consequence 
of  the  position  of  the  aorta  on  the 
left  of  the  median  line.    They  pass 


THE  AORTA.  1,  arch  of  the  aorta;  2,  thoracic 
aorta;  3,  abdominal  aorta;  4,  innominate  artery  : 
5,  right  common  carotid ;  6,  right  subclavian ;  7, 
left  common  carotid ;  8,  left  subclavian ;  9,  bron- 
chial artery,  a  small  branch  of  the  aorta ;  10,  ceso- 
phageal  arteries;  11,  intercostal  arteries  of  the 
right  side  ;  12,  of  the  left  side;  13,  phrenic  arteries ; 
14,  cceliac  axis;  15,  coronary  artery;  16,  splenic 
artery ;  17,  hepatic  artery;  18,  superior  mesenteric 
artery ;  19,  supra-renal  arteries  ;  20,  spermatic  ar- 
teries ;  21,  inferior  mesenteric  artery ;  22,  lumbar 
arteries ;  23,  common  iliac  arteries ;  24,  middle  sa- 
cral artery,  a,  aortic  orifice  of  the  diaphragm ;  6, 
articulation  of  the  head  of  the  ribs ;  c,  anterior 
scalene  muscle. 


1  A.   pericardiacae ;     a.    pericardiacae 
posteriores. 

2  A.  bronchiales ;  a.  b.  posteriores. 

3  A.  cesophageae. 


4  A.  mediastinicae. 

5  A.  intercostales ;  a.  i.  inferiores,  or 
aorticae. 


THE  VASCULAR  SYSTEM.  383 

from  their  origin  upward  and  outward  to  the  commencement  of  the  inter- 
costal spaces,  and  divide  into  an  anterior  and  a  dorsal  branch. 

a.  The  anterior  branch1  passes  outwardly  beneath  the  pleura,  enters 
between  the  two  intercostal  muscles,  and  then  runs  along  the  lower  bor- 
der of  the  uppermost  rib.     In  its  course  it  gives  branches  to  the  inter- 
costal, pectoral,  and  great  serrated  muscles ;  a  moderate-sized  one  which 
descends  and  runs  along  the  border  of  the  rib  below ;  and  others  which 
anastomose  with  the  anterior  intercostal  branches  of  the  internal  mam- 
mary artery,  and  the  thoracic  branches  of  the  axillary  artery.      The 
lower  three  of  the  anterior  branches  extend  into  the  abdominal  muscles, 
where  they  anastomose  with  the  epigastric  arteries.     In  the  female,  the 
anterior  branches  from  the  third  to  the  sixth  give  off  considerable  twigs2 
to  supply  the  mammary  gland. 

b.  The  dorsal  branch3  of  the  intercostals,  after  transmitting  a  branch4 
through  the  intervertebral  foramina  to  the  contents  of  the  spinal  canal, 
passes  backward  between  the  transverse  processes  of  the  vertebrae,  and 
is  distributed  to  the  muscles  of  the  back. 

ABDOMINAL  AOETA. 

The  Abdom'inal  Aor'ta5  commences  in  the  termination  of  the  thoracic 
aorta  as  it  emerges  through  the  aortic  orifice  of  the  diaphragm  opposite 
the  last  dorsal  vertebra.  Descending  in  front  of  the  vertebral  column 
with  a  slight  inclination  to  the  left  side,  opposite  the  fourth  lumbar  ver- 
tebra it  divides  into  the  two  common  iliac  arteries.  In  front  it  is  in 
relation  with  the  liver,  splenic  vein,  pancreas,  duodenum,  left  renal  vein 
and  peritoneum ;  and  to  its  right  is  the  inferior  cava,  with  the  right  crus 
of  the  diaphragm,  commencement  of  the  thoracic  duct  and  azygos  vein 
interposed  above. 

The  branches  of  the  abdominal  aorta  are  numerous,  and  many  of  them 
of  large  size.  Four  of  them  are  symmetrical  and  median  in  their  origin ; 
the  others  are  in  pairs.  The  symmetrical  branches  are  as  follow  : — 

Coeliac  axis. 

Superior  mesenteric  artery. 
Inferior  mesenteric  artery. 
Middle  sacral  artery. 

The  branches  in  pairs  are  as  follow : — 


1  Ramus  anterior,  or  intercostalis.  4  R.  spinalis ;  r.  vertebralis. 

2  Rami  mamraarii  extern!.  5  Aorta  abdominalis  ;  abdominal  por- 

3  R.  dorsalis ;  r.  posterior.  tion  of  the  descending  aorta. 


384 


THE   VASCULAR   SYSTEM. 


Phrenic  arteries. 
Supra-renal  arteries. 
Renal  arteries. 
Spermatic  arteries. 
Lumbar  arteries. 


THE  COELIAC  AXIS. 

The  Cce'liac  axis1  is  a  short,  thick  trunk,  projecting  forward  from  the 
commencement  of  the  abdominal  aorta.  It  is  in  relation  below  with  the 
pancreas,  and  with  the  semilunar  ganglion  on  each  side.  It  divides  into 
three  diverging  branches  as  follow : — 

1.  Coronary  artery. 

2.  Hepatic  artery. 

3.  Splenic  artery. 

FIG.  259. 


DISTRIBUTION  OF  THE  CCELIAC  ARTERY.  1,  liver  turned  upward,  and  showing  its  lower  surface ;  2,  trans- 
verse fissure;  3,  gall-bladder;  4,  stomach;  5,  oesophagus;  6,  7,  8,  duodenum;  9,  pancreas;  10,  spleen;  11, 
aorta;  12,  cceliac  artery;  13,  coronary  artery;  14,  hepatic  artery;  15,  pyloric  artery;  16,  gastro-duodenal 
artery;  17,  right  gastro-epiploic  artery;  18,  pancreatico-duodenal  artery;  19,  hepatic  artery  dividing  into 
the  right  and  left  branches  for  the  liver;  20,  splenic  artery;  its  course  indicated  behind  the  stomach  by 
dotted  lines;  21,  left  gastro-epiploic  artery;  22,  pancreatic  branch;  23,  gastric  branches;  24,  superior 
mesenteric  artery,  emerging  from  between  the  pancreas  and  duodenum. 

1.  The  Cor'onary  artery,2  the  smallest  of  the  divisions  of  the  coeliac 
axis,  turns  upward  and  to  the  left  side  toward  the  cardiac  orifice  of  the 

1  A.  cceliaca;  tripus  Halleri;  a.  epis-togastricus. 

2  A.  coronaria;  a.  c.  ventriculi;  a.  c.  v.  sinistra;  a.  gastrica  major;  a.  g.  sinistra 
superior;  a.  stomogastrica. 


THE  VASCULAR  SYSTEM.  385 

stomach,  and  then  runs  along  its  lesser  curvature.  Situated  between 
the  layers  of  the  lesser  oraentum,  it  divides  into  numerous  branches, 
which  supply  the  lower  part  of  the  oesophagus1  and  both  sides  of  the 
stomach,2  and  anastomose  with  all  the  other  arteries  of  the  latter. 

2.  The  Hepat'ic  artery,3  the  second  in  size  from  the  cceliac  axis,  in- 
clines upwardly  within  the  right  border  of  the  lesser  omentum,  and 
divides  into  two  branches  which  enter  the  transverse  fissure  of  the  liver. 
Behind  it  is  the  portal  vein,  and  to  its  right  the  bile  duct.  Its  branches, 
including  the  terminal  pair,  are  as  follow  : — 

a.  Pyloric  artery. 

6.  Gastro-duodenal  artery. 

c.  Pancreatico-duodenal  artery. 

d.  Right  gastro-epiploic  artery. 
e.  Right  branch. 

/.  Cystic  artery. 
g.  Left  branch. 

a.  The  Pylor'ic  artery4  is  a  small  branch  which  turns  downward  and 
runs  along  the  lesser  curvature  of  the  stomach  from  right  to  left,  anasto- 
mosing with  the  coronary  artery. 

6,  The  Gas'tro-duode'nal  artery,5  a  large  branch,  descends  behind  the 
pylorus,  and  divides  into  the  following  two  vessels  : — 

c.  The  Pancreat'ico-duode'nal  artery6  passes  between  the  head  of 
the  pancreas  and  the  duodenum,  and  supplies  both  with  branches.7 

d.  The  Right  gas'tro-epip'loic  artery8  runs  along  the  greater  curva- 
ture of  the  stomach  from  right  to  left,  and  terminates  by  conjunction 
with  the  left  gastro-epiploic.     It  gives  many  branches9  to  both  surfaces 
of  the  stomach  which  anastomose  with  those  from  the  lesser  curvature, 
and  it  also  sends  long  thread-like  vessels10  downward  to  the  great  omentum. 

e.  The  Right  branch11  of  the  hepatic  artery  enters  the  right  side 
of  the  transverse  fissure  of  the  liver,  and  divides  into  two  or  three 
branches,  which  penetrate  into  the  right  lobe  of  the  liver. 

/.  The  Cys'tic  artery,12  a  branch  of  the  preceding,  turns  forward  to 
supply  the  gall-bladder. 

1  Kami  oesophagei  inferiores.  ~  Kami  pancreatic!  dextri  and  r.  duode- 

2  Kami  cardiac!  and  gastric!.  nales. 

3  A.  hepatica.  8  A.  gastro-epiploica  dextra ;  a.  coro- 

4  A.  pylorica ;  a.  p.  superior ;  a.  coro-  naria  dextra  inferior ;    a.  c.  ventriculi, 
naria  dextra ;   a.  c.  ventriculi ;    a.  gas-  or  gastrica  dextra  inferior. 

trica  dextra  superior.  9  Rami  gastrici. 

5  A.  gastro-duodenalis.  10  Rami  epiploici. 

6  A.  pancreatico-duodenalis.  11  A.  hepatica  dextra. 

12  A.  cystica. 
25 


386  THE  VASCULAR  SYSTEM. 

g.  The  Left  branch1  of  the  hepatic  artery,  smaller  than  the  other, 
enters  the  left  of  the  transverse  fissure  to  be  distributed  to  the  corre- 
sponding lobe  of  the  liver. 

3.  The  Splen'ic  artery,2  the  largest  branch  of  the  coaliac  axis,  passes 
toward  the  left  side  in  a  tortuous  manner  along  the  upper  border  of  the 
pancreas  to  the  hilus  of  the  spleen.  Its  branches  are  as  follow  : — 

a.  Pancreatic  arteries. 

6.  Left  gastro-epiploic  artery. 

c.  Short  gastric  arteries. 

d.  Splenic  branches. 

a.  The  Pancreatic  arteries,3  variable  in  size  and  number,  are  given 
from  the  splenic  in  its  course  along  the  pancreas. 

b.  The  Left  gas'tro-epip'loic  artery4  runs  from  left  to  right  along 
the  greater  curvature  of  the  stomach,  and  terminates  by  joining  the  right 
gastro-epiploic,  like  which  it  is  also  distributed. 

c.  The  Short  gas'tric  arteries,5  three  to  six  in  number,  are  directed 
from  the  termination  of  the  splenic  artery,  or  some  of  its  branches,  to 
the  fundus  of  the  stomach,  where  they  anastomose  with  the  other  arteries 
of  that  organ. 

d.  The  Splen'ic  branches,6  five  or  more  in  number,  diverge  from  the 
parent  vessel  and  enter  the  hilus  of  the  spleen. 

THE  SUPERIOR  MESENTERIC  ARTERY. 

The  Superior  Mes'enteric  artery,7  a  large  vessel,  springs  from  the 
front  of  the  aorta  just  below  the  coeliac  axis,  and  supplies  the  small  in- 
testine and  the  right  portion  of  the  large  intestine.  It  descends  behind 
the  pancreas  and  in  front  of  the  duodenum,  and  then  proceeds  within 
the  mesentery  in  a  curved  line,  at  first  downward  and  to  the  left,  and 
then  toward  the  right  iliac  region,  where  it  inosculates  with  its  own  ileo- 
colic  branch. 

The  superior  mesenteric  artery  gives  off  the  following  branches  : — 

1.  Duodenal  artery. 

2.  Jejunal  and  ileal  arteries. 

3.  Ileo-colic  artery. 

4.  Right  colic  artery. 

5.  Middle  colic  artery. 

1  A.  hepatica  sinistra.  5  A.  gastricse  breves;  vasa  brevia. 

2  A.  splenica ;  a.  lienalis.  6  Kami  splenic! ;  r.  lienales. 

H  A.  pancreaticse.  7  A.  mesenterica  superior;  a.  mesara- 

4  A.  gastro-epiploica    sinistra;    a.  co-       ica  sup. 
ronaria  sinistra  inferior;  a.  c.  ventriculi, 
or  gastrica  sinistra  inferior. 


THE   VASCULAR   SYSTEM. 


387 


1.  The  Duode'nal  artery1  turns  back  along  the  course  of  the  duode- 
num, and  gives  branches  260 

both  to  it  and  the  pan- 
creas. 

2.  The    Jeju/nal    and 
Il'eal  arteries,2  fifteen  or 
more  in  number,  diverge 
from  the  convexity  of  the 
parent  vessel,  and  supply 
almost  the  whole  length 
of  the  small  intestine.  In 
their   course   within   the 
mesentery  they  divide, and 
the  contiguous  branches 
conjoin  so  as  to  form  a 
series  of  arches.       From 
these    spring     forth    a 
greater  number  of  branch- 
es, which  subdivide,  and, 
in  the  manner  just  indi- 
cated, form  a  second  se- 
ries of  arches,  and  from 
these  again  a  third  series 
is  formed.      Each  series 
of  arches  becomes  succes- 
sively more  numerous  and 

smaller,  and  from  the  last  series  originate  a  multitude  of  intestinal 
branches  which  diverge  upon  the  sides  of  the  jejunum  and  ileum,  where 
they  freely  anastomose  with  one  another. 

3.  4,  5.  The  Il'eo-colic,3  Right  Colic,4  and  Middle  Colic  arteries5 

arise  in  succession  from  the  right  side  or  concavity  of  the  superior  mes- 
enteric  artery.  Each  divides  into  two  branches,  of  which  those  contigu- 
ous, together  with  the  termination  of  the  parent  vessel  and  the  upper 
branch  of  the  left  colic  artery,  conjoin  so  as  to  form  four  large  arches. 
Upon  these,  in  the  manner  indicated  in  the  account  of  the  preceding 
arteries,  a  more  numerous  and  smaller  row  of  arches  is  formed,  from 


DISTRIBUTION  OF  THE  SUPERIOR  MESENTERIC  ARTERY.  1,  superior 
mesenteric  artery;  2,  jejunal  and  ileal  arteries;  3,  ileo-colic  ar- 
tery; 4,  right  colic;  5,  middle  colic  artery;  6,  duodenal  artery, 
a,  small  intestine  turned  to  the  left ;  b,  large  intestine ;  c,  pan- 
creas. 


1  A.  duodenalis  inferior;    a.  pancrea- 
tico-duodenalis  inferior. 

2  A.  jejunales  et  ileae;  a.  intestinales ; 
vasa  intestini  tenuis. 

3  A.  ileo-colica;  a.  colica  dextra  infe- 
rior ;   a.  csecalis. 


4  A.  colica  dextra ;  a.  c.  d.  media ;  a. 
media  anastomotica. 

5  A.  colica  media:  a.  colica  dextra  su- 
perior; a.  mesocolica. 


388 


THE   VASCULAR  SYSTEM. 


which  emanate  many  branches  to  supply  the  termination  of  the  ilium, 
the  caecum,  and  the  ascending  and  transverse  colon. 


THE  INFERIOR  MESENTERIC  ARTERY. 

The  Inferior  Mes'enteric  artery1  springs  from  the  front  of  the  aorta 

about  two  inches  below  the  superior  mesenteric,  and  is  destined  to  sup- 

FIG.  261.  ply  ^e  descending  colon 

and  the  rectum.  It  de- 
scends toward  the  left 
iliac  region  and  gives  off 
the  following  branches : — 

1.  Left  colic  artery. 

2.  Sigmoid  artery. 

3.  Superior  haemorrhoidal 

artery. 

1.  The  Left  Col'ic  ar- 
tery,2 directed  to  the  left 
side,  divides  into  two 
branches,  of  which  one 
joins  the  middle  colic  ar- 
tery, and  the  other  joins 
the  sigmoid  artery,  thus 
contributing  to  form  a 
pair  of  arches.  Upon 
these  a  series  of  irregular 
and  smaller  arches  is 
formed,  from  which 
branches  proceed  to  the 
descending  colon. 


DISTRIBUTION  OF  THE  INFERIOR  MESENTERIC  ARTERY.  1,  aorta ;  2, 
inferior  mesenteric  artery ;  3,  left  colic  artery ;  4,  sigmoid  artery ; 
5,  superior  hsemorrhoidal  artery;  6,  superior  mesenteric  artery;  7, 
middle  colic  artery  anastomosing  with  the  left  and  the  right  (8)  colic 
arteries ;  9,  branches  to  the  small  intestine ;  10,  left  renal  artery,  a, 
small  intestine  turned  to  the  right  side ;  b,  large  intestine ;  c,  pan- 
creas. 


2.  The  Sig'moid  ar- 
tery3 sometimes  originat- 
ing in  common  with  the  former,  and  sometimes  represented  by  two 
branches,  inosculates  with  the  left  colic  and  superior  haemorrhoidal 
arteries,  thus  producing  arches  from  which  branches  proceed  to  the  sig- 
moid flexure  of  the  colon. 

3.  The  Superior  haemorrhoidal  artery,*  the  terminal  portion  of  the 

1  A.  mesenterica,  or  mesaraica  inferior.  s  A.  colica  sinistra  inferior;    a.  c.  s. 

•    2  A.  colica  sinistra ;  a.  c.  s.  superior ;       parva. 

a.  c.  sinistra  magna  and  media.  *  A.  hsemorrhoidalis  superior,   or  in- 

terna. 


THE   VASCULAR   SYSTEM.  389 

inferior  mesenteric,  after  anastomosing  with  the  former,  descends  behind 
the  rectum  and  divides  into  two  branches,  distributed  on  the  sides  of 
the  latter,  and  anastomosing  with  the  middle  and  inferior  hemorrhoidal 
arteries. 

THE  MIDDLE  SACRAL  ARTERY. 

The  Middle  Sac'ral  artery1  is  a  small  vessel  descending  from  behind 
the  bifurcation  of  the  aorta  along  the  middle  of  the  sacrum  and  coccyx. 
It  is  really  a  rudimental  termination  of  the  aorta,  and  appears  as  a 
gradual  prolongation  of  the  latter  in  whales,  snakes,  and  other  animals 
in  which  hinder  extremities  do  not  exist  or  are  feebly  developed  in  com- 
parison with  the  tail.  In  its  course  it  gives  off  branches  which  anasto- 
mose with  the  lateral  sacral  arteries. 

ARTERIES  IN  PAIRS  FROM  THE  ABDOMINAL  AORTA. 

The  Phren'ic  arteries2  are  two  small  vessels  arising  from  the  sides  of 
the  abdominal  aorta  near  the  co3liac  axis,  or  from  the  latter  itself.  Di- 
verging on  the  crura  of  the  diaphragm,  the  right  one  passes  behind  and 
to  the  outer  side  of  the  inferior  cava,  while  the  left  one  proceeds  in  like 
manner  in  relation  with  the  O3sophagus,  and  both  divide  into  branches 
supplying  the  diaphragm,  anastomosing  with  the  phrenic  branches  of 
the  internal  mammary  and  the  terminations  of  the  intercostals. 

In  their  course  they  give  small  branches3  to  the  supra-renal  bodies. 

The  Liim/bar  arteries4  correspond  very  nearly  with  the  intercostals  in 
their  manner  of  origin,  direction,  and  distribution.  There  are  four  pairs 
of  them,  and  they  cross  the  bodies  of  the  lumbar  vertebra  beneath  the 
origin  of  the  crura  of  the  diaphragm  and  the  psoas  muscles,  to  the  inter- 
spaces of  the  transverse  processes,  where  they  divide  into  an  anterior 
and  a  posterior  branch. 

The  anterior  branch5  passes  outwardly  behind  the  quadrate  lumbar 
muscle,  ramifies  in  the  broad  abdominal  muscles,  and  anastomoses  with 
the  epigastric  arteries. 

The  posterior  branch,6  after  giving  off  a  spinal  branch,7  through  the 
intervertebral  foramina,  to  the  spinal  cord  and  membranes,  is  distributed 
to  the  muscles  and  skin  of  the  back. 

1  A.  sacralis   media;    a.   s.    anterior;  4  A.  lumbares,  a.  lumbales. 
median  artery  of  the  sacrum.  5  Ramus  lumbaris,  or  abdominalis. 

2  A.  phrenicse :  a.  p.  inferiores,  or  mag-  6  Ramus  dorsalis. 
nse ;  a.  diaphragmatic^.  7  R.  spinalis. 

3  A    supra-renales  superiores. 


390  THE   VASCULAR   SYSTEM. 

The  Supra-re'nal  arteries1  are  two  small  vessels  coming  from  the 
aorta  on  a  level  with  the  superior  mesenteric  artery,  and  proceed  out- 
ward to  be  distributed  to  the  supra-renal  bodies. 

The  Re'nal  arteries2  are  two  large  vessels  coming  from  the  sides  of 
the  aorta,  a  short  distance  below  the  position  of  the  superior  mesenteric 
artery.  The  right  one  is  usually  a  little  lower  than  the  left  one,  and  is 
longer  in  consequence  of  the  position  of  the  aorta  on  the  left  side  of 
the  vertebral  column.  Passing  directly  outward  and  backward  in  front 
of  the  crura  of  the  diaphragm,  they  divide  into  four  or  five  branches, 
which  enter  the  sinus  of  the  kidney  and  are  distributed  through  the 
organ.  They  also  give  small  branches  to  the  supra-renal  body,3  the  kid- 
jiey  fat,4  and  the  pelvis  and  ureter. 

Th,e  Sperma'tic  arteries5  are  long,  slender  vessels  which  spring  one 
from  each  side  of  the  front  of  the  aorta,  a  short  distance  below  the  renal 
arteries.  Each  descends  outwardly  upon  the  psoas  muscle,  in  company 
with  the  ureter,  but  leaves  the  latter  at  the  brim  of  the  pelvis,  and  pro- 
ceeds to  the  internal  abdominal  ring,  where  it  becomes  one  of  the  con- 
stituents of  the  spermatic  cord,  and  descends  to  be  distributed  to  the 
testicle.  It  gives  fine  twigs  to  the  ureter ;  near  the  testicle,  becomes 
quite  tortuous,  and  gives  branches  to  the  vaginal  tunic  of  the  organ. 

The  Ova'rian  arteries6  of  the  female  correspond  with  those  just  de- 
scribed of  the  male.  They  have  the  same  origin,  and,  likewise,  the  same 
course  as  the  spermatic  arteries  to  the  brim  of  the  pelvis,  after  which 
they  proceed  in  a  tortuous  manner  between  the  folds  of  the  broad  liga- 
ment to  the  ovary,  the  Fallopian  tube,  and  the  uterus. 

THE  COMMON  ILIAC  AETERIES. 

The  Common  Il'iac  arteries7  are  the  terminal  branches  of  the  abdom- 
inal aorta,  and  are  given  off  opposite  the  body  of  the  fourth  lumbar 
vertebra,  slightly  to  the  left  of  the  median  line.  The  two  vessels  diverge 
on  the  sides  of  the  fifth  lumbar  vertebra;  and  just  above  the  sacro-iliac 
symphysis  each  divides  into  the  internal  and  external  iliac  arteries. 

1  A.  supra-renales ;     a.   s.   mediae,    or  6  A.  spermaticse  ;    a.    s.   internae ;    a. 

norticae  ;  a.  capsulares  ;  a.  atrabilariae.  prneparantes ;  a.  testiculares. 
*  A.  renales;  a.  emulgentes.  c  A.  ovariana;  a.  spermatica. 

3  A.  supra-renales  inferiores.  t  A.  iliacae  communes ;  a.  i.  primitive; 

4  A.  adiposae.  primitive  or  primary  iliac  arteries ;  a. 

pelvicrurales. 


THE  VASCULAR   SYSTEM.  391 

The  common  iliacs  are  about  two  inches  in  length,  and  are  covered  by 
the  peritoneum  and  intestines.  The  right  one  crosses  over  both  common 
iliac  veins  as  these  converge  to  the  inferior  cava. 


FIG.  262. 


Vl«W  OF  THE  LEFT  SIDE  OF  THE  PELVIS,  THE  BLADDER,  UTERUS,  VAGINA,  AND  RECTUM,  turned  downward  SO 

as  to  exhibit  the  distribution  of  the  internal  iliac  artery.  1,  aorta;  2,  right  common  iliac  artery;  3,  left 
common  iliac;  4,  middle  sacral;  5,  external  iliac;  6,  circumflex  iliac;  7,  epigastric ;  8,  internal  iliac;  9, 
ilio-lumbar;  10,  lateral  sacral  arteries;  11,  gluteal  artery  passing  from  the  pelvis,  above  the  pyriform 
muscle,  at  the  upper  part  of  the  great  sacro-sciatic  foramen  ;  12,  superior  vesical  artery ;  the  branch  cut 
off  is  extended  into  the  remains  of  the  umbilical  artery;  13,  obturator  artery;  14,  inferior  vesical  artery 
giving  off  the  uterine  artery  to  the  vagina  and  uterus ;  15,  middle  hasmorrhoidal  artery ;  16,  internal  pu- 
dic  artery,  seen  emerging  from  and  again  entering  the  pelvis ;  17,  ischiatic  artery,  a,  iliac  muscle ;  b, 
psoas  muscle ;  c,  symphysis  of  the  pubis ;  d,  sacrum ;  e,  pyriforrn  muscle ;  /,  internal  obturator  muscle  ; 
g,  sacro-sciatic  ligaments ;  h,  rectum ;  i,  uterus  and  vagina ;  j,  Fallopian  tube ;  k,  bladder. 


THE  INTERNAL  ILIAC  ARTERY. 

The  Internal  Il'iac  artery1  is  a  short,  stout  vessel  which  descends 
from  the  common  iliac  into  the  pelvis,  the  contents  of  which,  the  but- 

1  A.  iliaca  interim  ;  a.  i.  posterior;  a.  hypogastrica ;  a.  pelvica. 


392  THE  VASCULAR  SYSTEM. 

tocks,  and  the  generative  apparatus  it  supplies.  It  extends  in  front  of 
the  sacro-iliac  symphysis  toward  the  great  sacro-sciatic  foramen,  and  di- 
vides into  two  portions,  which  usually  give  off  branches  in  the  following 
order: — 

From  the  posterior  division : — 

1.  Ilio-lumbar  artery. 

2.  Lateral  sacral  arteries. 

3.  Obturator  artery. 

4.  Gluteal  artery. 

From  the  anterior  division : — 

5.  Vesical  arteries. 

6.  Internal  pudic  artery. 

7.  Ischiatic  artery. 

In  addition,  in  the  female  there  come  off  from  the  anterior  division 
the  uterine  and  vaginal  arteries. 

1.  The  Il'io-lum'bar  artery1  passes  outward  beneath  the  psoas 
muscle,  and  divides  into  two  branches.  Of  these,  one2  ascends  and  sup- 
plies the  psoas  and  quadrate-lumbar  muscles,  and  anastomoses  with  the 
lumbar  arteries ;  the  other3  crosses  the  iliac  fossa  to  the  crest  of  the 
ilium  and  supplies  the  iliac  muscles,  and  anastomoses  with  the  circumflex 
iliac  artery. 

2.  The  Lateral  Sac'ral  arteries,4  usually  two,  sometimes  arising  in 
common,  descend  in  front  of  the  sacral  plexus  of  nerves,  anastomose 
with  the  middle  sacral  artery,  and  supply  the  pyriform,  coccygeal,  and 
anal  elevator  muscles.     Branches  derived  from  these  arteries  enter  the 
sacral  foramina  and  supply  the  contained  nerves  and  membranes,  and  in 
part  pass  out  at  the  posterior  foramina  to  terminate  in  the  neighboring 
muscles  and  skin. 

3.  The  Obtura'tor  artery,5  often  a  branch  of  the  anterior  division  of 
the  internal  iliac,  passes  forward  along  the  side  of  the  pelvis  to  the  ob- 
turator foramen,  through  which  it  emerges  and  divides  into  two  branches. 
Of  these,  the  internal  branch6  is  distributed  to  the  adductor,  pectineal, 
and  gracilis  muscles,  and  anastomoses  with  the  internal  circumflex  artery. 
The  external  branch7  is  distributed  to  the  obturator,  quadrate  femoral, 

1  A.  ilio-lumbaris ;  a.  ilia  parva.  5  A.  obturatoria ;    a.  sub-pubio-femo- 

2  Ramus  ascendens  ;  r.  lumbaris.  ralis. 

3  R.  transversalis ;  r.  iliacus.  6  Ramus  interims ;  r.  anterior. 

4  A.  sacrales  laterales.  7  R.  externus ;  r.  posterior. 


THE  VASCULAR  SYSTEM.  393 

and  geminous  muscles,  to  the  hip  joint,  and  to  the  heads  of  the  flexors 
attached  to  the  tuberosity  of  the  ischium.  Within  the  pelvis  the  obtura- 
tor artery  gives  small  branches  to  the  iliac,  internal  obturator,  and  anal 
elevator  muscles. 

Frequently  the  obturator  artery  arises,  in  common  with  the  epigastric, 
from  the  termination  of  the  external  iliac  artery,  in  which  cases  it  de- 
scends behind  the  pubis  to  the  obturator  foramen,  from  whence  it  pursues 
the  ordinary  course. 

4.  The  Glu'teal  artery,1  the  continuation  of  the  posterior  division  of 
the  internal  iliac,  turns  out  of  the  pelvis  at  the  upper  part  of  the  great 
sacro-sciatic  foramen,  and  divides  into  two  branches.     The  superficial 
branch  runs  backward  between  the  middle  and  great  gluteal  muscles, 
which  it  supplies,  together  with  the  skin  of   the  gluteal  and   sacral 
regions.    The  deep  branch  passes  forward  between  the  middle  and  small 
gluteal  muscles,  diverging  into  many  branches,2  which  supply  the  latter 
and  anastomose  with  the  ischiatic  and  circumflex  arteries. 

5.  The  Ves'ical  arteries3  are  generally  two  in  number.    The  superior 
ves'ical  artery4  extends  through  the  remains  of  the  umbilical  artery  of 
the  foBtus  to  the  side  of  the  urinary  bladder,  to  which  it  is  distributed. 
In  its  course  it  gives  the  deferent  artery  to  the  spermatic  duct,  and  a 
branch  to  the  ureter.    The  inferior  ves'ical  artery3  proceeds  to  the  lower 
part  of  the  bladder,  and  also  supplies  the  prostate  gland  and  seminal 
vesicles. 

6.  The  Internal  Pu'dic  artery,6  one  of  the  terminal  branches  of  the 
anterior  division  of  the  internal  iliac,  descends  to  the  lower  part  of  the 
great  sacro-sciatic  foramen,  and  thence  passes  from  the  pelvis.    Winding 
around  the  spine  of  the  ischium,  it  again  enters  the  pelvis  through  the 
small  sacro-sciatic  foramen,  ascends  along  the  inner  side  of  the  rami  of 
the  ischium  and  pubis,  and  divides  into  the  cavernous  and  dorsal  arteries 
of  the  penis.    Its  branches,  including  the  terminal  ones,  are  as  follow : — • 

a.  Middle  haemorrhoidal  artery. 

b.  Inferior  haemorrhoidal  artery. 

c.  Perineal  artery. 

d.  Bulbo-urethral  artery. 

e.  Cavernous  artery. 

/.  Dorsal  artery  of  the  penis,  or  clitoris. 

1  A.  glutaea ;  a.  g.  superior  ;   a.  iliaca          5  A.  v.  inferior. 

posterior.  6  A.  pudica  interna ;  a.  pudica ;  a.  pu- 

2  Deep  superior  and  inferior  branches.  denda ;  a.  p.  interna ;  a.  p.  communis ;  a. 

3  A.  vesicse  ;  a.  vesicales.  p.  circumflexa ;   a.  hsemorrhoidea  exter- 

4  A.  v.  superior.  na. 


394 


THE   VASCULAR   SYSTEM. 


FIG.  263. 


a.  The  Middle  hsemorrhoid'al  artery1  proceeds  from  the  pudic  before 

it  issues  from  the  pelvis, 
and  supplies  the  lower 
part  of  the  rectum,  the 
fundus  of  the  bladder,  and 
the  prostate  gland.  It 
anastomoses  with  the  su- 
perior and  inferior  hae- 
morrhoidal  arteries. 
Sometimes  it  comes  di- 
rectly from  the  internal 
iliac,  or  it  may  come  off 
in  common  with  the  infe- 
rior vesical  artery. 

b.  The  Inferior  hsemor- 
rhoid'al  artery2  is  a  small 
branch  which  comes  from 
the  pudic  after  it  re-enters 
the    pelvis,    and    is    dis- 
tributed to  the  parts  about 
the  anus. 

c.  ThePerine'al  artery3 
becomes     superficial    by 
piercing  the  deep  perineal 

7,  perineal  branch  to  the  scrotum  and  skin  of  the  penis ;  8,  bulbo-  fagcja    an(J    jg    distributed 

urethra!  artery;   9,  cavernous  artery;    10,  dorsal  artery  of  the 

penis,    a,  tuberosity  of  the  ischium;  6,  greater  sacro-sciatic  lig-  to  the  perineum  and  back 

ament;  c,  sphincter  of  the  anus;  d,  perineal  fascia,  which  is  re-  part    of    the    SCrotum  *  OT 

moved  on  the  opposite  side  so  as  to  expose  the  anal  elevator  muscle;  . 

e,  ischio-cavernous  muscle;  /,  bulbo-urethral  muscle.  labia.5    A  branch  Crossing 

the  perineum  on  the  trans- 
verse perineal  muscle,  and  important  in  its  surgical  relations,  is  named 
the  transverse  perineal  artery.6 

d.  The  Bul'bo-ure'thral  artery,7  derived  from  the  pudic  just  before 
its  division,  or  from  one  of  its  terminal  branches,  passes  transversely 
inward,  and  pierces  the  triangular  ligament  to  reach  the  bulb  of  the 
spongy  body,  which  it  penetrates  to  supply  the  erectile  tissue. 

e.  The  Cav'ernous  artery,8  a  terminal  branch  of  the  pudic,  runs  a 


VIEW  OF  THE  PERINEUM,  EXHIBITING  THE  DISTRIBUTION  OF  THE  IN- 
TERNAL PUDIC  ARTERY.  1,  the  internal  pudic  issuing  from  the  pel- 
vis at  the  lower  part  of  the  great  sacro-sciatic  foramen ;  2,  the 
same  vessel  after  it  has  returned  into  the  pelvis  through  the  small 
sacro-sciatic  foramen ;  3,  inferior  haemorrhoidal  artery ;  4,  5,  super- 
ficial perineal  branches  to  the  perineum ;  6,  transverse  perineal ; 


1  A.  hsemorrhoidalis  media. 

2  A.  haemorrhoidalis  inferior;  a.  h.  ex- 
terna. 

3  A.  perinei ;  a.  superficialis  perinei. 

4  A.  scrotales  posteriores  et  a.  septi. 


5  A.  labiales  posteriores. 

6  A.  transversa  perinei. 

7  Artery  of  the  bulb  ;  bulbar  artery ; 
a.  bulbosa;  a.  bulbo-urethralis. 

8  A.  cavernosa ;  a.  profunda  penis. 


THE   VASCULAR   SYSTEM.  395 

short  distance  between  the  ramus  of  the  ischium  and  the  cms  of  the  cav- 
ernous body,  and  enters  this  to  supply  its  erectile  tissue. 

/.  The  Dorsal  artery  of  the  penis,1  or  clitoris,2  the  second  terminal 
division  of  the  pudic,  ascends  between  the  pubis  and  cavernous  body  to 
the  back  of  the  latter,  along  which  it  proceeds  to  the  glans.  It  supplies 
the  fibrous  investment  of  the  cavernous  body,  the  glans,  and  the  skin, 
and  anastomoses  with  branches  of  the  bulbo-urethral  and  cavernous 
arteries. 

7.  The  Ischiat'ic  artery,3  the  remaining  branch  of  the  anterior  divi- 
sion of  the  internal  iliac,  passes  from  the  pelvis  in  company  with  the 
pudic  artery  and  great  sciatic  nerve,  at  the  lower  part  of  the  great 
sacro-sciatic  foramen.     Descending  in  the  interval  of  the  tuberosity  of 
the  ischium  and  the  great  trochanter,  covered   by  the   great   gluteal 
muscle,  it  gives  branches  to  the  latter,  the  small  rotators  upon  which  it 
rests,  the  skin  about  the  coccyx,4  the  sciatic  nerve,5  and  hip  joint,  and 
it  anastomoses  with  the  gluteal  and  circumflex  arteries. 

8.  The  U'terine  artery,6  a  branch  of  the  anterior  division  of  the  in- 
ternal iliac,    sometimes   arising  in  common  with  the  superior  vesical 
artery,  passes  within  the  broad  ligament  and  ascends  in  ,a  tortuous  man- 
ner to  the  side  of  the  uterus.    It  also  gives  branches  to  the  vagina,  Fal- 
lopian tube,  round  ligament,  and  ovary,  and  anastomoses  with  the  ovarian 
artery. 

9.  The  Vag'inal  artery,7  a  branch  of  the  anterior  division  of  the 
internal  iliac,  sometimes  arising  in  common  with  the  uterine,  inferior 
vesical,  or  middle  heemorrhoidal  artery,  supplies  the  walls  of  the  vagina 
and  the  contiguous  parts  of  the  rectum  and  urinary  bladder. 

THE  EXTERNAL  ILIAC  ARTERY. 

The  External  Il'iac  artery,8  the  second  division  of  the  common  iliac, 
runs  along  the  brim  of  the  pelvis,  resting  against  the  psoas  muscle,  to  the 
femoral  arch,  beneath  which  it  passes  out  to  assume  the  name  of  femoral 
artery.  The  corresponding  iliac  vein  at  first  is  behind  it,  and  afterwards 
to  its  inner  side.  It  gives  off  no  branches  of  importance  until  it  is 
about  passing  under  the  femoral  arch,  when  it  sends  off  the  epigastric 
and  circumflex  iliac  arteries. 

1  A.  dorsalis  penis.  5  Comes  nervis  ischiadici. 

'*  A.  d.  clitoridis.  fi  A.  uterina;   a.  u.  hypogastrica. 

3  A.  ischiadica ;  a   glutaea  inferior  ;  a.  7  A.  vaginalis. 

sciatica;  a  femoro-poplitea.  »  A.  iliaca  externa;  a.  i.  anterior;  cru- 

4  A.  coccygeeo.  ral  artery  ;  a.  cruralis;   a.  c.  iliaca. 


396  THE   VASCULAR   SYSTEM. 

1.  The  Epigastric  artery1  springs  from  the  fore  part  of  the  external 
iliac,  and  ascends  obliquely  inward,  between  the  peritoneum  and  trans- 
verse fascia,  to  the  straight  muscle  of  the  abdomen.    Piercing  the  sheath 
of  this  muscle,  and  ascending  behind  it,  the  artery  mainly  supplies  the 
latter,  and  anastomoses  with  the  termination  of  the  mammary  artery. 
In  its  course  it  crosses  the  inguinal  canal  and  gives  a  branch2  to  the 
spermatic  cord.     Subsequently  it  gives  branches  to  the  broad  abdominal 
muscles,  which  anastomose'  with  the  lumbar  and  circumflex  iliac  arteries. 

2.  The  Circumflex  Il'iac  artery,3  smaller  than  the  preceding,  runs 
outward  from  the  external  iliac,  behind  Poupart's  ligament,  to  the  crest 
of  the  ilium.     Proceeding  along  the  latter,  it  gives  branches  to  the  iliac 
and  abdominal  muscles,  and  anastomoses  with  the  ilio-lumbar,  lumbar, 
and  epigastric  arteries. 

THE  FEMORAL  ARTERY. 

The  Fern/oral  artery,4  the  continuation  of  the  external  iliac,  proceeds 
from  the  femoral  arch,  downward  and  inward,  in  the  groove  of  the  thigh, 
between  the  extensor  and  adductor  muscles.  Becoming  gradually  deeper 
in  its  descent,  at  about  the  commencement  of  the  lower  third  of  the 
thigh  it  pierces  the  insertion  of  the  great  adductor  muscle,  and  assumes 
the  name  of  popliteal  artery.  It  passes  through  the  middle  of  a  tri- 
angular space,  whose  base  is  formed  by  Poupart's  ligament,  the  outer 
side  by  the  sartorius  muscle,  and  the  inner  side  by  the  border  of  the 
adductor  muscles.  A  line  extended  from  the  middle  of  the  groin  to  the 
inner  side  of  the  knee-cap  would  nearly  indicate  its  course.  In  succes- 
sion, it  rests  on  the  pectineal,  long  adductor,  and  great  adductor  muscles. 
At  the  femoral  arch  the  corresponding  vein  lies  at  its  inner  side,  but 
gradually  assumes  a  position  behind  as  it  approaches  the  perforation  of 
the  great  adductor.  At  the  upper  third  of  the  thigh  it  is  covered  by 
the  skin  and  fascia ;  lower  down,  in  addition,  by  the  sartorius  muscle. 

The  branches  of  the  femoral  artery  are  as  follow : — 

1.  External  pudic  arteries. 

2.  Superficial  epigastric  artery. 

3.  Superficial  circumflex  iliac  artery. 

4.  Profound  femoral  artery. 

5.  Muscular  branches. 

6.  Anastomotic  artery. 

1.  The   External  Pu'dic   arteries5  are  two  or  three   small  vessels 

1  A.  epigastrica;  a.  e.  inferior;  a  e.  i.           4  A.  femoralis;    a.  cruralis ;    a.  pelvi- 
interna.  cruralis. 

2  A.  spermatlca  externa.  5  A.  pudendae  externse;  a.  pudenda  ex- 

3  A.  circumflexa  iliaca.  terna  superior  et  inferior;  a.  scrotales  et 

labiales  anteriores. 


THE   VASCULAR  SYSTEM. 


897 


from  the  commencement  of  the  femoral  artery,  which  pass   through 

the  pectineal  and  cribriform  fasciae  FJG  264 

to  the  region  of  the  pubis,  where  «*« 

they  are  distributed  to  the  skin  of 

the  penis  and  scrotum,  or,  in  the 

female,  to  the   mons  veneris   and 

labia. 

2.  The  Superficial  Epigas'tric 
artery1  arises   a  little   below  the 
femoral  arch,  perforates  the  falci- 
form process,  and  ascends  in  the 
superficial  fascia  of  the  abdomen 
toward  the  umbilicus. 

3.  The  Superficial  Circumflex 
il'iac  artery,2  often  a  branch  of  the 
preceding,    follows    the   course    of 
Poupart's  ligament   to   the  ilium, 
dividing  into  branches  which  pierce 
the  fascia  and  supply  the  groin3  and 
integument. 

ARTERIES  OF  THE  FRONT  OF  THE  THIGH.  1,  femoral 
artery ;  2,  popliteal  artery ;  3,  posterior  tibial  ar- 
tery ;  4,  superficial  epigastric  artery ;  5,  superficial 
circumflex  iliac;  6,  external  pudics;  7,  profound 
femoral  artery ;  8,  9,  external  and  internal  circum- 
flex arteries;  10, perforating  arteries;  11,  muscular 
branches ;  12,  anastomotic  artery ;  13, 14,  internal 
articular  arteries ;  15,  small  branch  from  the  epi- 
gastric ;  16,  dorsal  arteries  of  the  penis,  a,  rectus 
muscle ;  b,  internal  vastus ;  c,  d,  e,  adductor  mus- 
cles ;  /,  semi-tendinous  muscle ;  g,  sartorius  muscle. 

4.  The  Profound  Fern/oral  ar- 
tery* comes  from  the  outer  back 
part  of  the   femoral,   an   inch   or 
two  below  Poupart's  ligament,  and 
is  nearly  as  large  as  the  continu- 
ation of  the  parent  trunk.     It  de- 
scends behind  the  latter,  proceeds 

between  the  short  and  long  adductors,  and  thence  upon  the  great  ad- 
ductor, which  is  perforated  by  its  terminal  branches.  In  its  course  it  is 
distributed  through  the  following-named  branches  : — 


1  A.  epigastrica  superficialis ;  a.  abdo-       externa;  ramus  iliacus  of  the  sup.  epi- 
minalis  subcutanea  ;  a.  ad  cutem  abdo-       gastric. 

3  A.  inguinales. 

femoralis 


minis. 

2  A.  circumflexa   ilii   superficialis  or 


4  A.  profunda   femoris ; 
profunda. 


398  THE   VASCULAR  SYSTEM. 

a.  Internal  circumflex  artery. 
6.  External  circumflex  artery, 
c.  Perforating  arteries. 

a.  The  Internal  cir'cumflex  artery1  comes  from  the  commencement 
of  the  profound  femoral,  and  turns  backward  between  the  psoas  and 
pectineal  muscles,  above  the  lesser  trochanter,  to  the  posterior  part  of 
the  neck  of  the  femur.    In  its  course  it  gives  branches  to  the  iliac,  psoas, 
pectineal,  gracilis,  and  external  obturator  muscles,2  the  heads  of  the  ad- 
ductors, and  the  hip  joint.3    In  terminating  it  divides  into  two  branches, 
of  which  one*  ascends  to  supply  the  small  rotators  and  the  lower  part  of 
the  great  gluteal  muscle,  anastomosing  with  the  ischiatic  and  gluteal 
arteries ;  while  the  other  branch5  descends  and  supplies  the  quadrate 
femoral  muscle  and  the  heads  of  the  great  adductor  and  flexors  of  the 
thigh. 

b.  The  External  circumflex  artery,6  larger  than  the  preceding,  and 
arising  a  little  lower,  passes  outward  between  the  iliac  and  rectus  muscles 
and  divides  into  a  series  of  ascending  and  descending  branches.     The 
former  supply  the  tensor  of  the  femoral  fascia,  the  sartorius,  rectus, 
small  and  middle  gluteal,  and  external  vastus  muscles ;  the  latter  supply 
the  quadriceps  extensor  and  the  skin  on  the  outer  part  of  the  thigh. 

c.  The  Perforating  arteries,7  three  or  four  in  number,  are  successive 
divisions  of  the  profound  femoral  artery  which  pierce  the  insertion  of  the 
adductors  to  reach  the  back  of  the  thigh,  where  they  are  resolved  in 
branches  supplying  the  great  gluteal,  adductor,  and  flexor  muscles,  and 
anastomosing  with  the  ischiatic  and  circumflex  arteries  and  with  one 
another.      The  medullary  nutritious    arteries  of   the  femur8  are 
branches  of  the  perforating  arteries. 

5.  The  Muscular  branches9  of  the  femoral  artery  are  small  vessels 
given  off  in  the  course  of  the  latter  to  the  sartorius,  gracilis,  extensor, 
and  adductor  muscles. 

6.  The  Anastomotric  artery10  is  a  slender  vessel  springing  from  the 
femoral  as  this  is  about  to  pass  through  the  perforation  of  the  great 

1  A.  circumflexa  interna;  a.  c.  femoris  7  A.  perforantes;  a.  perfovans  prima, 
interna,  or  posterior.                                         secunda,  et  tertia. 

2  Ramus  superficialis.  8  A.  nutritise  ;  a.  nutritia  femoris  su- 

3  A.  articularis ;  a.  acetabuli.  perior  et  inferior,  or  magna. 
*  Ramus  trochantericus.  9  Rami  musculares. 

5  R.  descendens.  10  A.  anastomotica  magna;  ramus  mus- 

6  A.  circumflexa  externa;  a.  c.  femoris       culo-articularis  and  a.  articularis  genii 
externa,  or  anterior.  superficialis,  or  a.  a.  g.  s.  superior  inter- 
na or  prima. 


THE   VASCULAR   SYSTEM. 


399 


adductor.  Descending  upon  the  tendon  of  the  latter  and  giving  it 
branches,  it  also  supplies  the  internal  vastus,  sartorius,  and  gracilis 
muscles,  and  terminates  at  the  knee  by  anastomosing  with  all  the  other 
contiguous  arteries. 


THE  POPLITEAL  ARTERY. 


ARTERIES  OF  THE  BACK  OF  THE  THIGH.  1,  gluteal 
artery;  2,  3,  its  superficial  and  deep  branch;  4,  in- 
ternal pudic  artery;  5,  ischiatic  artery;  6,  branch 
of  the  external  circumflex ;  7, 8,  terminal  branches 
of  the  perforating  arteries;  9,  popliteal  artery;  10, 
11,  superior  internal  and  external  articular  ar- 
teries ;  12,  13,  inferior  internal  and  external  artic- 
ular arteries;  14,  middle  articular  artery  ;  15,  gas- 
trocnemial  branches,  a,  origin  and  insertion  of  the 
great  gluteal  muscle;  b,  origin  of  the  middle  glu- 
teal muscle;  c,  small  gluteal  muscle;  d,  great  tro- 
chanter;  e,  pyriform  muscle;  /,  sacro-aciatic  lig- 
aments ;  g,  internal  obturator  muscle ;  h,  quadrate 
femoral  muscle ;  i,  sciatic  nerve ;  j,  tuberosity  of 
the  ischium ;  A-,  external  vastus  muscle ;  I,  great 
adductor;  TO,  short  head  of  the  biceps;  «,  long 
head;  o, p,  semi-membranous  and  semi-tendinous 
muscles ;  q,  gracilis ;  r,  gastrocnemius. 

The  Poplite'al  artery1  is  the 
name  assumed  by  the  femoral  after 
its  passage  through  the  tendon 
of  the  great  adductor  at  the 
lower  third  of  the  thigh.  It 
extends  along  the  back  of  the  lat- 
ter, behind  the  middle  of  the  knee 
joint,  to  the  lower  border  of  the 
popliteal  muscle,  where  it  divides 
into  the  anterior  and  posterior 
tibial  arteries.  Occupying  the  deep- 
est part  of  the  popliteal  space,  it 
rests  in  succession  against  the  fe- 
mur, the  capsular  ligament  of  the 
knee  j  oint,  and  the  popliteal  muscle. 
In  contact  with  it  posteriorly  is  the 
corresponding  vein ;  between  which 
and  the  skin  is  the  posterior  tibial 
nerve.  The  branches  of  the  popli- 
teal artery,  including  the  terminal 
ones,  are  as  follow  : — 


FIG.  265. 


//r 
' 


1  A.  poplitea;  popliteal  portion  of  the  crural  artery. 


400  THE  VASCULAR  SYSTEM. 

1.  Articular  arteries. 

2.  Muscular  branches. 

3.  Anterior  tibial  artery. 

4.  Posterior  tibial  artery. 

1.  The  Artic'ular  arteries1  are  five  small  vessels  which  spring  from 
the  popliteal  artery  and  supply  the  knee  joint  and  its  contiguous  struc- 
tures.    The  superior  articular  arteries2  wind  around  the  femur,  one 
above  each  condyle,  to  the  front  of  the  knee  joint.     Of  the  inferior 
articular  arteries,3  one  turns  around  the  external  semilunar  cartilage, 
while  the  other  takes  its  course  below  the  internal  condyle  of  the  tibia ; 
both  reaching  the  front  of  the  knee.     These  four  vessels,  together  with 
the  anastomotic  and  recurrent  tibial  arteries,  produce  an  intricate  vas- 
cular net,4  enveloping  the  front  and  sides  of  the  knee.     The  middle 
articular  artery3  penetrates  the  back  of  the  capsular  ligament  and  sup- 
plies the  crucial  ligaments  and  synovial  folds  of  the  knee  joint. 

2.  The  Muscular  branches  of  the  popliteal  artery  consist  of  two  or 
three  from  its  upper  part  to  the  flexor  and  vast!  muscles,  and  one  or 
two6  from  its  lower  part  to  the  gastrocnemius  muscle  and  skin  of  the 
calf. 

THE  ANTERIOR  TIBIAL  ARTERY. 

The  Anterior  TiVial  artery,7  the  smaller  of  the  terminal  divisions  of 
the  popliteal,  passes  through  the  opening  at  the  upper  part  of  the  inter- 
osseous  membrane,  and  descends  in  front  of  this  to  the  instep,  where  it 
assumes  the  name  of  dorsal  pedal  artery.  It  is  accompanied  by  two 
companion  veins  and  the  anterior  tibial  nerve  ;  at  first  lies  between  the 
long  extensor  of  the  toes  and  the  anterior  tibial  muscle,  and  afterwards 
between  the  latter  and  the  extensor  of  the  great  toe.  At  the  ankle  it  is 
crossed  by  the  tendon  of  the  muscle  last  named,  and  is  covered  by  the 
annular  ligament.  Its  branches  are  as  follow: — 

1.  Recurrent  tibial  artery. 

2.  Muscular  branches. 

3.  External  malleolar  artery. 

4.  Internal  malleolar  artery. 

1  A.  articulares ;  a.  a.  genu  superiores,  6  A.  art.  genu  media ;  a.  a.  genu  azy- 
inferiores,  et  media.  gos. 

2  A.  articularis  superior  interna  et  ex-  6  A.  surales  ;    a.  gemellse  ;    a.  surales 
terna ;    a.  a.  genu  sup.  int.  secunda  or  profundae  et  superficialis ;  gastrocnemial 
profunda  and  a.  a.  g.  s.  externa.  or  sural  arteries. 

3  A.  art.  inferior  interna  et  externa.  7  A.  tibialis  antica. 
*  Rete  articulare  genu. 


THE   VASCULAR   SYSTEM. 


401 


FIG.  266. 


1.  The  Recurrent  Tib'ial  artery1  ascends  beneath  the  origin  of  the 
anterior  tibial  muscle  to  the  front  of  the  knee,  and 

is  there  distributed,  anastomosing  with  the  articu- 
lar arteries. 

2.  The  Muscular  branches  are  numerous  small 
vessels  to  the  contiguous  muscles. 

3.  The  External  Malle'olar  artery2  passes  out- 
wardly at  the  lower  part  of  the  leg,  beneath  the 
extensor   tendons,  and   ramifies   on  the   external 
ankle,  supplying  the  neighboring  structures,  and 
anastomosing  with  the  peroneal  and  tarsal  arteries. 


4.  The  Internal  Mal- 
le'olar artery,3  small- 
er than  the 'preceding,  tibial;  3> dorsal  Pedal ;  *.  5,  external 

and  internal  malleolar  arteries;   6, 


ARTERIES  OF  THE  FRONT  OF  THE  LEG. 
1,  anterior  tibial  artery;  2,  recurrent 


passes  beneath  the  ten- 
don of  the  anterior 
tibial  muscle  and  rami- 
fies over  the  internal 
ankle,  anastomosing 
with  branches  of  the 
posterior  tibial  and 
tarsal  arteries. 


metatarsal  artery  ;  7,  dorsal  artery  of 
the  great  toe  ;  8,  terminal  branches 
of  the  articular  arteries,  a,  tibia;  b, 
anterior  tibial  muscle;  c,  extensor 
of  the  great  toe  ;  d,  long  extensor  of 
the  toes  :  the  short  extensor  occupies 
the  back  of  the  foot;  e,  peroneal 
muscles  :  on  each  side  of  the  leg  the 
bellies  of  the  gastrocnemius  are  visi- 
ble. 


THE  DORSAL  PEDAL  ARTERY. 

The  Dorsal  Pe'dal  artery,4  the  continuation  of 
the  anterior  tibial,  extends  from  the  bend  of  the 
ankle  over  the  instep  to  the  commencement  of  the 
first  interosseous  space,  where  it  dips  to  the  sole 
of  the  foot  to  contribute  in  the  formation  of  the 
plantar  arch.  Its  branches  are  as  follow : — 

1.  Tarsal  arteries. 

2.  Metatarsal  artery. 

3.  Dorsal  artery  of  the  great  toe. 

1.  The  Tar 'sal  arteries5  consist  of  several  small  branches  to  the  inner 


1  A.  tibialis  recurrens. 
-  A.  malleolaris  externa. 
3  A.  malleolaris  interna. 


4  A.  dorsalis  pedis. 

5  A.  tarseae;  a.  t.  internae  and  externee. 


26 


402 


THE   VASCULAR   SYSTEM. 


side  of  the  tarsus,  and  a  large  branch  which  crosses  the  latter  beneath 
the  short  extensor  of  the  toes  and  supplies  the  outer  part  of  the  tarsus. 

FIG.  267.  2.  The  Metatar'sal  artery1  crosses  the  base  of 

the  metatarsus  and  supplies  the  outer  part  of  the 
foot,  anastomosing  with  the  tarsal  and  external 
plantar  arteries.  In  its  course  it  gives  off  branches2 
to  the  outer  three  metatarsal  spaces,  which  subse- 
quently subdivide3  to  supply  the  contiguous  sides 
of  the  outer  four  toes  and  the  outer  side  of  the 
little  toe. 

3.  The  Dorsal  artery  of  the  great  toe4  runs 
forward  on  the  first  interosseous  space,  and  sup- 
plies the  inner  and  outer  sides  of  the  great  toe 
and  the  adjoining  side  of  the  second  toe.5 


THE  POSTERIOR  TIBIAL  ARTERY. 


ARTERIES  OF  THE  BACK  OF  THE  LEG. 
1,  popliteal  artery;  2,  2,  superior  in- 
ternal and  external  articular  arteries;  ial  artery,6  the  remain- 
3,  3,  inferior  internal  and  external  .  division  Of  the  pop. 
articular  arteries;  4,  middle  articular 
artery ;  5,  gastrocnemial  arteries  ;  6, 
peroneal  artery;  7,  posterior  peroneal 
branch;  8,  posterior  tibial  artery ;  9, 
calcanean  branches,  a,  popliteal  mus- 
cle ;  b,  c,  origin  of  the  gastrocnemius ;  fae  ]e~  curves  arOUlld 
d,  peroneal  muscles ;  e,  long  flexor  of 
the  great  toe;  /,  long  flexor  of  the 
toes ;  that  between  the  two  latter  is 
the  posterior  tibial  muscle. 


The  Posterior  Tib'- 


liteal,  and  appearing 
as  a  continuation  of  it, 
descends  the  back  of 


the  inner  ankle  to  the 
concavity  of  the  calca- 
neum,  and  divides  into 
the  two  plantar  arteries.  It  is  accompanied  by  two 
veins  and  the  posterior  tibial  nerve,  and  is  situated 
behind  the  tibia,  with  the  posterior  tibial  and  long 
flexor  muscle  of  the  toes  interposed.  Its  upper 
part  is  covered  by  the  muscles  of  the  calf,  but  be- 
hind the  inner  ankle  is  covered  only  by  the  skin 
and  fascia.  Its  branches  are  as  follow  : — 


1  A.  metatarsea. 
L>  A.  interosseae. 

3  A.  digitales  dorsales ;  dorsal  collat- 
eral digital  branches. 


*  A.  dorsalis  liallucis  or  pollicis  pedis  ; 
a.  interossea  dorsalis  prima. 

5  A.  digitales  dorsales;  dorsal  collat- 
eral digital  branches. 

6  A.  tibialis  postica. 


THE  VASCULAR  SYSTEM.  403 

1.  Peroneal  artery. 

2.  Muscular  branches. 

3.  Medullary  nutritious  artery. 

4.  Calcanean  arteries. 

5.  Internal  plantar  artery. 

6.  External  plantar  artery. 

1.  The  Perone'al  artery1  arises  an  inch  or  two  below  the  commence- 
ment of  the  posterior  tibial,  and  turns  outward  to  descend  along  the  back 
of  the  fibula.     In  the  first  part  of  its  course  it  rests  on  the  posterior 
tibial  muscle,  covered  by  the  soleus ;   subsequently  lies  on  the  interos- 
seous  membrane  close  to  the  fibula,  and  is  covered  by  the  long  flexor  of 
the  great  toe.     It  gives  branches  to  the  contiguous  muscles,  and  finally 
divides  into  the  anterior  and  posterior  peroneal  arteries. 

a.  The  Anterior  peroneral  artery2  pierces  the  interosseous  membrane 
at  the  lower  part  of  the  leg,  and  is  distributed .  in  front  of  the  outer 
ankle,  anastomosing  with  the  external  malleolar  and  tarsal  arteries. 

b.  The  Posterior  perone'al  artery3  descends  along  the  -back  of  the 
outer  ankle  to  the  side  of  the  calcaneum,  distributing  branches  to  the 
heel*  and  parts  about  the  external  ankle.5    By  a  short  transverse  branch6 
it  anastomoses  with  the  posterior  tibial  artery ;  and  by  other  and  smaller 
branches  it  inosculates  with  the  external  malleolar,  tarsal,  and  external 
plantar  arteries. 

2.  The  Muscular  branches  of  the  posterior  tibial  artery  consist  of 
about  a  dozen  small  vessels  sent  to  the  contiguous  muscles. 

3.  The  Med'ullary  Nutritious  artery7  enters  the  corresponding  fora- 
men, at  the  upper  part  of  the  tibia,  to  supply  the  marrow. 

4.  The  Calca'nean  arteries8  are  two  or  three  branches  from  the  lower 
part  of  the  posterior  tibial  artery,  passing  inward  to  be  distributed  to 
the  heel,  the  tarsus,  and  the  heads  of  the  muscles  of  the  sole  of  the  foot. 

5.  The  Internal  Plant'ar  artery,9  one  of  the  terminal  divisions  of  the 
posterior  tibial,  runs  along  the  inner  side  of  the  sole  of  the  foot  above 
the  abductor  of  the  great  toe.     In  its  course  it  gives  deep  branches  to 
the  tarsus,  and  superficial  ones  to  the  contiguous  muscles  and  skin,  and 
ends  by  anastomosing  with  the  digital  arteries  of  the  great  toe. 

1  A.  peronea ;  a.  fibularis.  6  R.  anastomoticus  transversus. 

2  A.  peronea  antica ;  a.  p.  perforans.  7  A.  nutritia  tibiae ;  nutritious  artery. 

3  A.  p.  postica.  8  Rami  calcanei  interni. 

4  Rami  calcanei  externi.  »  A.  plantaris  interna. 

5  R.  malleolares  externi  postici. 


404 


THE   VASCULAR   SYSTEM. 


6,  The  External  Plant'ar  artery,1  larger  than  the  preceding,  inclines 

outward  and  forward  to  the  base 
of  the  last  metatarsal  bone,  and 
then  curves  inwardly  to  form,  in 
conjunction  with  the  termination 
of  the  dorsal  pedal  artery,  the  plan- 
tar arch.  In  its  course  it  lies  be- 
tween the  short  flexor  of  the  toes 
and  the  accessory  flexor,  and  sub- 
sequently between  the  latter  and 
the  short  flexor  of  the  little  toe. 
To  these  and  other  muscles,  and  the 
skin  on  the  inner  side  of  the  foot, 
it  gives  branches,  as  well  as  a  dig- 
ital branch2  to  the  outer  side  of 
the  little  toe. 

The  Plant'ar  arch,3  formed  by 
the  union  of  the  external  plantar 
and  dorsal  pedal  arteries,  lies 
against  the  interosseous  muscles 
at  the  base  of  the  metatarsus,  cov- 
ered by  the  flexor  muscles  and  ten- 
dons. Besides  giving  branches  to 
the  contiguous  muscles  and  articu- 
lations, it  sends  off  the  perforating 
and  digital  arteries. 

a.  The  Perforating  arteries4  are 
small  vessels  which  penetrate  between  the  bases  of  the  metatarsal  bones 
to  anastomose  with  the  interosseous  branches  of  the  metatarsal  artery. 
b.  The  Digital  arteries,5  four  in  number,  advance  in  the  corre- 
sponding spaces  to  the  clefts  of  the  toes,  and  there  divide  into  digital 
branches6  which  run  along  the  contiguous  sides  of  the  latter.  The  first 
digital  artery7  also  gives  a  digital  branch8  to  the  inner  side  of  the 
great  toe. 


ARTERIES  OF  THE  SOLE  OF  THE  FOOT.  1,  posterior 
tibial  artery  dividing  into  2  the  internal,  and  3  the 
external  plantar  arteries;  4,  branch  to  the  inner 
side  of  the  foot ;  5,  branch  to  the  great  toe;  6,  plan- 
tar arch;  7,  perforating  arteries;  8,  common  digi- 
tals ;  9,  digitals  to  the  contiguous  sides  of  the  toes ; 
10,  calcanean  branches  of  the  peroneal  and  poste- 
rior tibial  arteries. 


1  A.  plantaris  externa. 

a  A.  digitalis  plantaris  externa. 

3  Arcus  plantaris. 

*  A.  perforantes. 

5  A.  interosseae. 


6  A.  digitales  pedis  plantares;  plantar 
collateral  digital  branches. 

7  A.  magna  pollicis. 

8  A.  digitalis  plantaris  interna. 


THE   VASCULAR   SYSTEM.  495 


THE  PULMONARY  ARTERY. 

The  Pul'monary  artery,  one  of  the  main  trunks  of  the  arterial  system, 
conveys  dark  blood  from  the  heart  to  the  lungs.  It  is  a  short,  wide  ves- 
sel springing  from  the  anterior  part  of  the  base  of  the  right  ventricle, 
and  curves  for  about  two  inches  upward,  backward,  and  to  the  left  side. 
Its  origin  conceals  that  of  the  aorta,  but  higher  it  crosses  to  the  left 
side  ,of  the  latter  vessel,  in  front  of  the  left  auricle,  and  finally  divides  be- 
neath the  arch  of  the  aorta  into  two  branches — the  right  and  left  pulmo- 
nary arteries.  At  its  bifurcation  it  is  connected  to  the  under  side  of  the 
aortic  arch  by  a  short  fibrous  cord,  which  is  the  remains  of  a  vessel  of 
foetal  life  named  the  ductus  arteriosus. 

The  Right  Pulmonary  artery,  longer  than  the  left,  passes  nearly 
transversely  outward  behind  the  ascending  aorta  and  superior  cava  to 
the  root  of  the  right  lung,  of  which  it  forms  a  part. 

The  Left  Pulmonary  artery  passes  transversely  in  front  of  the  de- 
scending aorta  into  the  root  of  the  left  lung. 


THE  VEINS. 

The  Veins  comprise  eight  trunks,  with  their  branches,  as  follow  : — 

The  Cor'onary  vein,  which,  with  its  branches,  collects  blood  from  the 
walls  of  the  heart  and  conveys  it  to  the  right  auricle. 

The  Superior  and  Inferior  Cava,  by  whose  branches  blood  is  collected 
from  most  all  parts  of  the  body,  and  is  then  conveyed  to  the  right  auri- 
cle of  the  heart. 

The  Port'al  vein,  which  originates  by  many  branches  from  the  stom- 
ach, intestines,  spleen,  and  pancreas,  and  is  distributed  by  another  series 
of  branches  through  the  liver. 

The  four  Pul'monary  veins  which  convey  the  aerated  blood  from  the 
lungs  to  the  left  auricle  of  the  heart. 

THE  CORONARY  YEIN. 

The  Cor'onary  vein1  commences  at  the  apex  of  the  heart,  ascends 
in  the  groove  between  the  ventricles  in  front,  and  then  winds  around  the 
left  auriculo-ventricular  groove  to  the  back  of  the  heart,  where  it  term- 
inates in  the  right  auricle.  In  its  course  it  receives  car'diac  branches 


1  Vena  coronaria;  v.  c.  magna;  v.  cordis  magna;   great  cardiac  vein;   coronary 
sinus  of  the  heart. 


406  THE  VASCULAR  SYSTEM. 

from  both  ventricles,  and  from  the  left  auricle.  Its  orifice  is  protected 
by  a  valve.1 

The  Posterior  Car'diac  vein2  commences  at  the  apex  of  the  heart, 
and  ascends  between  the  ventricles  posteriorly  to  terminate  in  the  coro- 
nary vein.  In  its  course  it  receives  cardiac  branches  from  J^th  ven- 
tricles. 

The  Anterior  Car'diac  vein,3  frequently  represented  by  a  pair  of 
veins,  runs  from  the  front  of  the  heart  along  the  right  auriculo- ventricu- 
lar groove  to  terminate  posteriorly  in  the  coronary  vein.  In  its  course 
it  receives  cardiac  branches  from  the  right  auricle  and  ventricle.  Be- 
sides these  several  small  cardiac  veins4  ascend  from  the  right  ventricle 
to  open  separately  into  the  right  auricle. 

THE  SUPERIOR  CAVA. 

The  Superior  Cava5  is  the  great  venous  trunk  which  derives  its 
branches  from  the  head,  neck,  upper  extremities,  and  walls  of  the  tho- 
rax. .  It  is  placed  to  the  right  of  the  aortic  arch  in  front  of  the  root  of 
the  right  lung,  and  commences  behind  the  first  costal  cartilage  of  the 
right  side  by  the  conjunction  of  the  two  innominate  veins.  In  its 
descent  it  receives  the  azygos  vein,  and  terminates  at  the  upper  back 
part  of  the  right  auricle  of  the  heart.  It  is  less  voluminous  than  the 
arch  of  the  aorta,  and  is  destitute  of  valves. 

THE  INNOMINATE  VEINS. 

The  Innominate  veins6  commence  one  on  each  side,  behind  the 
sterno-clavicular  articulation,  by  the  union  of  the  internal  jugular  and 
subclavian  veins.  The  Right  innom'inate  vein7  descends  in  front  of 
the  corresponding  artery ;  the  Left  innominate  vein,8  much  longer  than 
the  other,  crosses  in  front  of  the  arteries  springing  from  the  summit  of 
the  aortic  arch  to  the  right  side,  where  it  joins  its  fellow  to  form  the 
superior  cava. 

The  innominate  veins  are  destitute  of  valves,  and,  besides  the  branches 

1  Valvula  Thebesii;    v.  Guiffartiana;  5  Vena  cava  superior;  v.  c.  descendens; 
v.  venae  magnae.                                                  v.  c.  thoracica ;  v.  hepatites. 

2  V.  cordis    media ;     middle   cardiac          6  Venae  innominatae  ;  v.  anonymae  ;  v. 
vein.  brachio-cephalicae. 

3  V.  cordis  parva ;  small,  or  anterior  7  V.  innominata  dextra. 

cardiac  vein.  8  V.  innominata  sinistra ;  v.  transversa; 

4  V.  cordis  minimae  ;  smallest  cardiac      the  transverse  vein, 
veins. 


THE   VASCULAR   SYSTEM. 


407 


which  conjoin  in  their  formation, 
they  receive  the  internal  mammary, 
vertebral,  and  inferior  thyroid 
veins,  and  usually  the  left  superior 
intercos{J|  vein. 

The  Internal  Mam/mary  veins,1 
a  pair  of  companions  to  the  corre- 
sponding artery,  receive  branches 
in  accordance  with  the  distribution 
of  the  latter,  and  finally  unite  to 
terminate  in  the  innominate  vein ; 
though  frequently  the  left  one  joins 
the  superior  cava. 

The  Vertebral  vein2  is.  a  small 
vessel  occupying  the  foramina  of 
the  transverse  processes  of  the  cer- 
vical vertebrae  in  company  with  the 
vertebral  artery.  It  commences 
from  branches  on  the  occiput,  re- 
ceives others  in  its  course  down 
the  neck  from  the  neighboring 
muscles  and  spinal  sinuses,  and 
terminates  in  the  innominate  or 
subclavian  vein. 

The  Inferior  Thy'roid  vein,3 
formed  by  numerous  branches  in 
the  thyroid  gland,  also  receives 
others  from  the  pharynx,  larynx, 
oesophagus,  and  trachea,  and  ter- 
minates in  the  innominate  vein. 
Sometimes  the  veins  of  the  two 
sides  conjoin  in  a  single  vessel4  de- 
scending in  front  of  the  trachea  to 
end  in  the  middle  of  the  left  in- 
nominate vein. 


VEINS  OF  THE  THORAX  AND  ABDOMEN.  1,  inferior 
cava;  2,  right,  3  left  renal  veins;  4,  superior  cava; 
5,  right.  6  left  innominate  veins;  7,  internal  veins; 
8,  external  jugular  veins ;  9,  subclavian  vein ;  10, 
azygos  vein ;  11  inferior,  12  superior  hemiazygos 
veins. 


1  V.  mammarise  internee.  2  V.  vertebralis.  3  V.  thyroidea  inferior. 

4  V.  thyroidea  ima:  v.  t.  impar;  v.  t.  axygos. 


408 


THE   VASCULAR  SYSTEM. 


YEINS  OF  THE  HEAD  AND  NECK. 

The  two  Ju'gular  veins1  are  the  principal  ones  of  the  head  and  neck, 
and  are  situated  at  the  side  of  the  latter.     The  internal  jugular  vein 

FIG.  270. 


VEINS  OF  THE  HEAD  AND  NECK.  1,  frontal  vein ;  2,  nasal  vein ;  3, 4,  labial  veins ;  5,  facial  vein ;  6,  lingual 
vein;  7,  internal  jugular  vein;  8,  9,  posterior  and  anterior  temporal  veins;  10,  transverse  facial  vein ;  11, 
internal  maxillary  vein  ;  12,  posterior  auricular  vein ;  13,  external  jugular  vein;  14  posterior,  15  anterior 
jugular  veins,  a,  external  carotid  artery;  b,  sterno-mastoid  muscle;  c,  trapezius;  d,  pectoral  muscle;  e, 
deltoid  muscle. 

corresponds  with  the  deep  veins  which  accompany  the  large  arteries  of 
the  limbs.     It  receives  the  blood  from  the  interior  of  the  cranium  and 

1  V-  jugulares;  v.  soporales;  v.  apoplecticae ;   v.  sphagitides. 


THE  VASCULAR  SYSTEM.  409 

orbit — usually  the  greater  part  of  that  of  the  exterior  of  the  cranium, 
and  generally  most  of  that  of  the  face  and  neck.  The  external  jugular 
vein  corresponds  with  the  large  superficial  veins  of  the  limbs,  and  re- 
ceives a  portion  of  the  blood  from  the  exterior  of  the  cranium,  and 
usually  f^m  the  face  and  neck. 

All  the  veins  of  the  head  and  neck,  except  the  jugulars,  are  destitute 
of  valves. 

THE  INTERNAL  JUGULAR  VEIN. 

The  Internal  Ju'gular  vein1  commences  in  a  bulb-like  dilatation2 
at  the  jugular  foramen  of  the  cranium,  and  there  receives  the  blood 
of  the  sinuses  of  the  dura  mater.  It  descends  the  neck  at  the  outer 
side  of  the  internal  and  common  carotid  arteries,  and  finally  conjoins 
with  the  subclavian  to  form  the  innominate  vein.  In  its  course  down 
the  neck  it  generally  receives  the  facial,  lingual,  pharyngeal,  superior 
thyroid,  and  occipital  veins,  and  sometimes  the  tempero-maxillary  vein 
in  whole  or  part. 

The  internal  jugular  vein  varies  in  size  reciprocally  with  that  of  the 
opposite  side,  and  with  the  size  of  the  external  jugular  vein.  More 
frequently  that  of  the  right  side  is  the  larger.  Further,  it  often  varies 
in  the  number  of  branches  which  conjoin  to  form  it  on  the  two  sides  of 
the  neck.  Its  lower  part  is  frequently  more  or  less  dilated,  and  at  the 
termination  is  provided  with  a  pair  of  valves. 

SINUSES  OF  THE  DURA  MATER. 

The  Si'nuses  of  the  Dura  Mater3  are  venous  channels  formed  between 
the  layers  of  the  latter  membrane  and  lined  with  a  continuation  of  the 
ordinary  lining  membrane  of  blood-vessels.  They  receive  the  veins  of 
the  brain  and  its  membranes,  those  of  the  bones  of  the  cranium,  and 
those  of  the  orbit ;  and  the  blood  obtained  from  all  these  sources  they 
convey  to  the  internal  jugular  veins.  They  are  destitute  of  valves,  and 
do  not  accompany  corresponding  arteries. 

The  Lateral  Sinus,4  on  each  side  of  the  cranial  cavity,  is  the  main 
channel  to  which  all  the  other  sinuses  converge.  It  commences  at 
the  internal  occipital  protuberance,  in  the  so-called  confluence  of  the 

1  V.  jugularis  interna;  v  j.magna;  v.  3  Sinus  durae  matris;  fistulae,  cavita- 
j.  cerebralis;   v.  cephalica;  v.  apoplec-  tes,  ventriculi,  tubuli,  sanguiductus,  or 
tica.  receptacula  durae  matris. 

2  Bulbus  venae  jugularis ;  gulf  or  si-  4  S.  lateralis  ;  s.  transversus ;  s.  ten- 
nus  of  the  jugular  vein.  torii  posterior;  s.  t.  sigmoidus;  s.  mag- 

nus. 


410 


THE   VASCULAR   SYSTEM. 


sinuses,1  which  is  produced  by  the  union  of  the  superior  longitudinal, 
straight,  and  posterior  occipital  sinuses.     Proceeding  outwardly  along 

the  groove  of  the  trans- 
verse limb  of  the  occip- 
ital cross,  it  tlmn  curves 
downward  and  inward  in 
the  groove  of  the  mas- 
toid  portion  of  the  tem- 
poral bone,  and  termin- 
ates at  the  jugular  foram- 
en by  joining  the  jugular 
vein. 

The  Superior  Longi- 
tudinal sinus,2  a  single 
channel  for  the  two  sides 
of  the  cranial  cavity,  com- 
mences at  the  bottom  of 
the  frontal  crest,  and  pro- 
ceeds backward  along  the 
convex  border  of  the  cere- 
bral falx  to  the  confluence 
of  the  sinuses.  It  is  tri- 
lateral, increases  in  size 
from  before  backward, 
and  gives  rise  to  the  shal- 
low groove  along  the  me- 
dian line  of  the  cranial 
vault.  It  receives  the 
superior  and  median  ce- 
rebral veins. 

The  Inferior  Longitu- 
dinal sinus3  is  a  single  small  vessel  which  runs  along  the  concave  border 
of  the  cerebral  falx,  and  terminates  posteriorly  in  the  straight  sinus. 

The  Straight  sinus,4  single  for  the  two  sides  of  the  cranium,  is  situ- 
ated along  the  conjunction  of  the  cerebral  falx  with  the  tentorium,  and 


SINUSES  AT  THE  BASE  OF  THE  CRANIUM,  with  the  right  orbit  ex- 
posed, a,  eyeball;  Coptic  nerve;  c,  occipital  foramen ;  d,e,f, 
anterior,  middle,  and  posterior  cranial  fossae.  1,  confluence  of  the 
sinuses  from  which  the  lateral  sinus  on  each  side  passes  off  to 
terminate  at  the  jugular  foramen;  2,  ophthalmic  vein;  3,  cavern- 
ous sinus;  4,  circular  sinus  surrounding  the  pituitary  fossae ;  5, 
anterior  occipital  sinus;  6,  7,  superior  and  inferior  petrosal  sin- 
uses; 8,  posterior  occipital  sinus;  9,  commencement  of  the  in- 
ternal jugular  vein. 


1  Confluens    sinuum ;    torcular   Hero- 
phili;  wine-press  of  Herophilus;  fourth 
sinus. 

2  Sinus  longitudinalis  superior ;  s.  fal- 
ciformis;  s.  f.  superior;  s.  triangularis; 
s.  medianus. 


3  S.  longitudinalis  inferior ;    s.  falci- 
formis;    s.   f.   inferior;   s.  minor;  vena 
falcis  cerebri. 

4  S.  rectus;  s.  quartus;  s.  tentorii;  s. 
perpendicularis ;  s   obliquus ;  s.  choroi- 
deus. 


THE   VASCULAR  SYSTEM. 


411 


terminates  in  the  confluence  of  the  sinuses.  It  is  trilateral — at  its  com- 
mencement receives  the  preceding  sinus  and  the  ventricular  veins,  and  in 
its  course  receives  veins 

from  the  neighboring  FIG.  272. 

parts  of  the  cerebrum  and 
cerebellum. 

The  Cav'ernous  sinus1 
is  situated  at  the  side  of 
the  pituitary  fossa,  and 
is  short  but  capacious. 
Its  cavity  is  crossed  by 
fibrous  bands  or  offsets 
of  the  dura  mater,  from 
whence  the  sinus  derives 
its  name.  A  more  re- 
markable peculiarity  con- 
sists in  its  walls  inclosing 
the  ophthalmic,  pathetic, 
oculo-motor,  and  abdu- 
cent nerves,  and  the  in- 
ternal carotid  artery, 
which,  however,  are  sep- 
arated from  its  cavity  by 

the  lining  membrane.  Its  fore  part  receives  the  ophthalmic  vein,  and 
its  back  part  communicates  with  the  petrosal  sinuses. 

The  Circular  sinus2  surrounds  the  pituitary  body,  and  communicates 
on  each  side  with  the  cavernous  sinus. 

The  Superior  Petro'sal  sinus3  is  a  narrow  channel  which  extends  from 
the  cavernous  sinus,  along  the  border  of  the  tentorium  attached  to  the 
edge  of  the  petrous  portion  of  the  temporal  bone,  to  the  lateral  sinus. 

The  Inferior  Petro'sal  sinus4  extends  from  the  cavernous  sinus  along 
the  lower  border  posteriorly  of  the  petrous  portion  of  the  temporal  bone 
to  join  the  termination  of  the  lateral  sinus. 

The  Anterior  Occip'ital  sinus,5  sometimes  represented  by  a  pair  of 


VERTICAL  SECTION  OF  THE  SKULL,  exhibiting  the  sinuses  of  the 
dura  mater.  1,  superior  longitudinal  sinus ;  2,  termination  of  the 
superior  cerebral  veins;  3,  inferior  longitudinal  sinus;  4,  internal 
cerebral  veins;  5,  straight  sinus;  6, 7,  superior  and  inferior  petrosal 
sinuses  of  the  right  side;  8,  right  lateral  sinus;  9,  commencement 
of  the  left  lateral  sinus;  10,  internal  jugular  vein,  a,  cerebral 
falx ;  b,  tentorium ;  c,  cerebellar  fossa ;  d,  partition  of  the  nose ; 
e,  frontal  sinus;  /,  sphenoidal  sinus. 


1  S.  cavernosus  ;  receptaculum. 

2  S.  circularis;  s.  c.  Ridleyi;  s   coro- 
narius;  s.  ellipticus. 

3  S.  petrosus  superior ;  s.  tentorii  late- 
ralis. 


4  S.  p.  inferior. 

6  S.  occipitalis  anterior ;  s.  basilaris  ; 

transversus. 


412  THE   VASCULAR   SYSTEM. 

sinuses,  is  a  transverse  channel  of  communication  between  the  inferior 
petrosal  sinuses,  across  the  basilar  process  of  the  occipital  bone. 

The  Posterior  Occip'ital  sinus,1  frequently  represented  by  a  pair  of 
sinuses,  commences  in  small  veins  at  the  sides  of  the  occipital  foramen, 
and  ascends  along  the  convex  border  of  the  cerebellar  falx  to  terminate 
in  the  confluence  of  the  sinuses. 


VEINS  OF  THE  BRAIN. 

The  veins  which  emanate  from  the  substance  of  the  brain  form  an  in- 
tricate net-work  in  the  pia  mater,  and  collect  into  large  branches  which 
generally  follow  the  course  of  the  fissures  on  the  surface  of  the  brain 
to  the  nearest  sinuses  of  the  dura  mater. 

The  Superior  Cer'ebral  veins2  ascend  from  the  outer  surface  of  the 
cerebral  hemispheres,  and  terminate  in  the  superior  longitudinal  sinus. 
They  pierce  the  dura  mater  obliquely  and  open  forward  into  the  sinus. 

The  Median  Cer'ebral  veins3  ascend  from  the  sides  of  the  longitudinal 
fissure  to  the  superior  longitudinal  sinus. 

The  Inferior  Cer'ebral  veins4  open  into  the  nearest  sinuses :  those 
from  the  fore  part  of  the  cerebrum  into  the  cavernous  sinuses,  those  from 
the  back  part  into  the  lateral  and  straight  sinuses,  and  those  intermediate 
into  the  superior  petrosal  sinuses. 

The  Internal  Cer'ebral  veins,5  two  in  number,  pass  backward  along 
the  middle  of  the  choroid  membrane  of  the  third  ventricle,  and,  united  in 
a  short  trunk,6  or  separately,  terminate  in  the  commencement  of  the 
straight  sinus.  They  derive  branches  from  the  choroid  plexuses,  striate 
bodies/  thalami,  fornix,  and  cerebral  crura. 

The  Superior  Cerebel'lar  veins8  terminate  in  the  straight  sinus. 

The  Inferior  Cerebel'lar  veins,9  together  with  branches  from  the  pous 
and  medulla  oblongata,  end  in  the  inferior  petrosal,  posterior  occipital, 
and  lateral  sinuses. 

1  S.  occipitalis;  s.  o.  posterior.  e  y.  magna  Galeni. 

2  V.  cerebrales  superiores.  7  Vena  choroidea  et  corporis  striati. 

3  V.  c.  medianae.  8  y.  cerebelli  superiores. 

4  V.  c.  inferiores.  9  y.  cerebelli  inferiores. 
3  V.  cerebri  internae  ;  v.  c.  magnae  ;  Y. 

Galeni;  v.  choroidese. 


THE   VASCULAR   SYSTEM.  413 


THE  DIPLOIC  AND  MENINGEAL  YEINS. 

The  Dip'loic  veins1  ramify  in  the  spongy  structure  of  the  bones  of  the 
cranium,  and  communicate  with  the  neighboring  veins  of  the  scalp,  orbit, 
and  dura  mater,  or  with  the  sinuses  of  the  latter  membrane. 

The  Menin/geal  veins,2  of  which  two  accompany  each  corresponding 
artery,  continue  in  the  course  of  the  arteries  or  terminate  in  the  sinuses 
of  the  dura  mater.  The  Great  menin'geal  veins3  either  terminate  in  the 
internal  maxillary  vein  or  in  the  cavernous  sinus. 

THE  OPHTHALMIC  VEIN. 

The  Ophthalmic  vein,4  possessing  the  same  general  arrangement  as 
the  corresponding  artery,  commences  at  the  internal  canthus  of  the  eye, 
where  it  anastomoses  with  the  facial  vein.  Passing  back  along  the  inner 
part  of  the  orbit,  it  emerges  at  the  sphenoidal  foramen  to  end  in  the 
cavernous  sinus. 

THE  EXTERNAL  JUGULAR  VEIN. 

The  External  JVgular  vein,5  much  smaller  than  the  internal  jugular, 
is  formed  by  the  union  in  whole  or  part  of  the  tempero -maxillary  with 
the  posterior  auricular  vein,  or  it  may  be  a  continuation  of  the  latter 
alone  or  in  union  with  the  facial  vein. 

It  descends  from  the  vicinity  of  the  angle  of  the  jaw,  crossing  the 
sterno-mastoid  muscle  under  cover  of  the  subcutaneous  cervical  muscle, 
and  terminates  behind  the  middle  of  the  clavicle  by  joining  the  sub- 
clavian  vein.  It  usually  possesses  a  valve  about  the  middle  of  its  course, 
and  another  at  its  termination.  Besides  its  branches  of  origin,  it  gen- 
erally receives  the  following : — 

The  Anterior  jugular  vein,6  from  the  front  of  the  neck. 

The  Posterior  jugular  vein,7  from  the  back  of  the  neck. 

The  Supra-scap'ular  vein,8  pursuing  the  direction  of  the  correspond- 
ing artery. 

The  Transverse  cer'vical  vein,9  likewise  a  companion  of  the  corre- 
sponding artery. 

1  V.  diploeticae.  e  y.  jugularis  anterior;  v.  j.  mediana 

'l  V.  meningeae.  colli ;  v.  cutanea  colli  anterior. 

3  V.  m.  magnae  ;  v.  m.  mediae.  7  V.  jugularis  posterior. 

4  V.  ophthalmica.  s  y.  supra-scapularis. 

5  V.  jugularis  externa;  v.  cutanea  colli  »  V.  transversa  cervicis. 
posterior ;  v.  trachelo-subcutanea. 


414  THE   VASCULAR  SYSTEM. 


THE  FACIAL  VEIN. 

The  Fa'cial  vein1  pursues  the  general  course  of  the  facial  artery,  but  is 
less  tortuous,  and  is  more  posteriorly  situated.  It  commences  at  the  in- 
ternal canthus  of  the  eye,  under  the  name  of  the  Angular  vein,2  which  is 
usually  visible  during  life  through  the  skin.  In  this  position  it  anasto- 
moses with  the  ophthalmic  vein,  and  commonly  receives  the  Frontal  vein.3 
The  latter  communicates  with  the  temporal  veins,  and  descends  near  the 
middle  of  the  forehead  to  the  root  of  the  nose,  across  which  it  frequently 
anastomoses  with  the  opposite  vein ;  and  it  often  terminates  in  the  oph- 
thalmic vein. 

Near  the  angle  of  the  jaw  the  facial  vein  most  frequently  ends  in  the 
internal  jugular,  and  sometimes  joins  the  tempero-maxillary  vein  to 
empty  with  it  into  the  external  jugular,  or  it  may  terminate  in  the 
latter  alone.  In  its  course  it  generally  receives  the  following  branches : — 

The  Supra-orb'ital  vein,4  which  runs  along  the  superciliary  ridge  and 
receives  the  superior  pal/pebral  veins5  from  the  upper  eyelid. 

The  Na'sal  veins,6  from  the  side  of  the  nose. 

The  Inferior  pal'pebral  veins,7  from  the  under  eyelid. 

The  Masseter/ic  and  Buc'cal  veins,8  from  the  cheek. 

The  Labial  veins,9  from  the  lips. 

The  Submen'tal  vein,10  from  the  vicinity  of  the  chin. 

The  Submax'illary  veins,11  from  the  corresponding  gland. 

The  Pal'atine  vein,12  from  the  soft  palate  and  tonsil. 

THE  TEMPORAL  VEIN. 

The  Tem'poral  vein13  and  its  branches  have  the  same  general  course  as 
the  corresponding  arteries,  but  are  less  tortuous.  The  anterior  temporal 
vein14  anastomoses  with  the  frontal  vein ;  the  posterior  temporal15  with 
the  occipital  vein.  The  common  temporal  penetrates  the  parotid  gland, 
and  at  the  neck  of  the  lower  jaw  usually  unites  with  the  internal  maxil- 

1  V.  facialis;  v.  f.  anterior,  or  interna;  8  V.  massetericae  et  buccales. 
v.  palato-labialis.  9  V.  labiales. 

2  V.  angularis.  10  V.  submentalis. 

3  V.  frontalis ;  v.  preparata.  n  V.  submaxillares. 

4  V.  supra-orbitalis.  12  V.  palatina. 

5  V.  palpebrales  superiores.  13  V.  temporalis ;  v.  facialis  posterior ; 

6  V.  nasalis  dorsalis  et  lateralis,  pin-       v.  f  externa ;  v.  carotis  externa. 
nalis,  or  alaris.  u  V.  temporalis  superficialis  anterior. 

7  V.  palpebrales  inferiores.  15  V.  t.  s.  posterior. 


THE  VASCULAR  SYSTEM.  415 

lary  vein  to  form  the  tempero-maxillary  vein.  In  its  course  it  receives 
the  following  branches  : — 

The  Artic'ular  veins,1  from  a  plexus2  behind  the  articulation  of  the 
lower  jaw. 

The  Anterior  auric'ular  veins,3  from  the  front  of  the  auricle  or  ear. 

The  Middle  temporal  vein,4  following  the  course  of  the  artery  of  the 
same  name. 

The  Transverse  fa'cial  vein,5  likewise  following  the  corresponding 
artery. 

The  Parot'id  veins,6  from  the  parotid  gland. 

THE  INTERNAL  MAXILLARY  YEIN. 

The  Internal  Max'illary  vein7  springs  from  a  plexus  which  is  situated 
between  the  pterygoid  muscles,  in  contact  with  the  maxillary  artery,  and 
receives  the  veins  which  accompany  the  latter.  It  is  a  short  vessel  which 
passes  behind  the  neck  of  the  lower  jaw,  and  joins  the  temporal  vein 
within  the  parotid  gland,  or  it  is  represented  by  a  pair  of  vessels,  both 
joining  the  temporal  vein,  or  one  may  join  the  latter  and  the  other  may 
descend  to  near  the  angle  of  the  jaw,  to  end  in  the  internal  jugular  vein. 

THE  TEMPERO-MAXILLARY  YEIN. 

The  Tem/pero-max'illary  vein,8  formed  by  the  conjunction  of  the 
temporal  with  the  whole  or  part  of  the  internal  maxillary  vein,  descends, 
in  company  with  the  external  carotid  artery,  through  the  parotid  gland, 
and  joins  with  the  posterior  auricular  vein  to  form  the  external  jugular 
vein.  Sometimes  it  divides,  partly  to  contribute  in  the  formation  of  the 
latter,  and  partly  to  join  with  the  facial  vein  to  empty  into  the  internal 
jugular  vein  ;  and  not  unfrequently  it  entirely  joins  with  the  facial  vein 
to  terminate  in  the  internal  jugular. 

THE  POSTERIOR  AURICULAR  YEIN. 

The  Posterior  Auric'ular  vein,9  pursuing  the  course  of  the  corre- 
sponding artery,  joins  with  the  tempero-maxillary  vein,  in  whole  or  part, 

1  V.  articulares.  e  y  parotidese. 

2  Plexus  articularis  posterior.  t  y.  maxillaris  interna ;  deep  branch 

3  V.  auriculares  anteriores  et  v.  auri-       of  the  posterior  facial  vein. 

cularis  profunda.  s  y,   tempero  maxillaris ;    v.  facialis 

4  V.  temporalis  media  or  profunda.  posterior. 

5  V.  transversa  facei.  »  V.  jyiricularis  posterior. 


41G  THE   VASCULAR   SYSTEM. 

to  form  the  external  jugular  vein  ;  or,  in  those  cases  in  which  the  former 
terminates  in  conjunction  with  the  facial  in  the  internal  jugular  vein,  it 
is  the  sole  origin  of  the  external  jugular. 

THE  OCCIPITAL  VEIN. 

The  Occip'ital  vein1  follows  the  general  course  of  the  corresponding 
artery,  and  usually  terminates  in  the  internal  jugular  vein,  but  sometimes 
in  the  external  jugular.  A  communication  between  it  and  the  lateral 
sinus  is  established  by  means  of  the  mastoid  vein,  which  passes  through 
a  foramen  of  the  temporal  bone. 

THE  VEINS  OF  THE  TONGUE. 

The  Dorsal  Lin'gual  vein2  receives  its  branches  from  the  upper  part 
of  the  tongue,  the  tonsils,  and  epiglottis,  and  pursues  the  course  of  the 
lingual  nerve,  to  end  in  the  facial,  pharyngeal,  or  either  jugular  vein. 

The  Ranine  vein3  commences  under  the  tip  of  the  tongue,  where  it  is 
visible  through  the  mucous  membrane,  and  passes  back  in  the  course  of 
the  hypoglossal  nerve  to  terminate  in  the  facial  or  either  jugular  vein. 

THE  PHARYNGEAL  VEIN. 

The  Pharynge'al  vein4  is  derived  from  a  plexus  on  the  sides  and  back 
of  the  pharynx,  and  descends  to  terminate  on  a  level  with  the  hyoid  bone 
in  the  internal  jugular  vein. 

THE  SUPERIOR  THYROID  VEINS. 

The  Superior  Thy'roid  veins,5  usually  two  in  number,  are  derived 
from  the  upper  part  and  side  of  the  thyroid  gland,  and  from  the  larynx 
and  trachea,  and  terminate  in  the  internal  jugular  vein,  or  occasionally 
in  the  lingual  or  facial  vein. 

THE  VEINS  OF  THE  UPPER  EXTREMITIES. 

The  veins  of  the  upper  extremities  consist  of  a  deep  and  a  superficial 
series,  of  which  the  former  follow  the  arteries,  while  the  latter  pursue  an 
independent  course  beneath  the  skin,  but  finally  terminate  in  the  main 

1  V.  occipitalis.  5  V.  thyroidea  superiores ;  v.  thyroidea 

2  V.  dorsalis  linguae.  superior  et  media  et  v.  laryngea  et  v. 

3  V.  ranina.  pharyngea  inferior. 

4  V.  pharyngea. 


THE  VASCULAR  SYSTEM.  417 

trunk  of  the  deep  veins.  The  two  series  have  frequent  anastomotic 
communications,  and  are  provided  with  many  valves,  which  are  more 
numerous  in  the  deep  veins. 

THE  SUBCLAYIAN  VEIN. 

The  Subcla'vian  vein1  is  the  continuation  of  the  axillary  vein,  and 
usually  receives  at  its  commencement  the  external  jugular  vein.  As  it 
passes  over  the  first  rib  it  is  separated  from  the  subclavian  artery  by  the 
insertion  of  the  anterior  scalene  muscle.  It  is  destitute  of  valves,  and 
by  conjunction  with  the  internal  jugular  forms  the  innominate  vein. 

THE  DEEP  VEINS  OF  THE  UPPER  EXTREMITY. 

The  Deep  Veins  of  the  upper  extremity  closely  follow  the  arteries, 
every  one  of  these  except  the  axillary  artery  possessing  a  pair  o,f  com- 
panion veins  which  anastomose  with  each  other  by  occasional  transverse 
offsets  crossing  the  vessel  they  accompany. 

Of  the  two  Bra'chial  veins,  the  internal  one  is  the  larger,  and  usually- 
just  above  the  middle  of  the  arm  it  receives  the  basilic  vein,  which  be- 
longs to  the  superficial  set.  In  the  axilla  the  two  brachial  veins  unite 
to  form  the  Ax'illary  vein,  and  as  this  passes  beneath  the  clavicle  it  re- 
ceives the  cephalic  vein  of  the  superficial  set,  and  finally  becomes  the 
subclavian  vein. 

THE  SUPERFICIAL  VEINS  OF  THE  UPPER  EXTREMITY. 

The  Superficial  veins  of  the  upper  extremity  are  generally  larger 
than  the  deep  ones,  and  are  not  the  companions  of  arteries.  Through 
numerous  anastomoses  they  form  a  net-work  enveloping  the  limb  beneath 
the  skin.  In  fat  persons  they  are  inclosed  in  the  adipose  layer  of  the 
superficial  fascia,  but  in  thin  persons,  and  under  ordinary  circumstances, 
are  for  the  most  part  visible  through  the  integument.  They  have  fre- 
quent anastomotic  communication  with  the  deep  veins,  and  finally  term- 
inate in  the  main  trunks  of  the  latter. 

The  TJl'nar  cuta'neous  veins,2  usually  two  in  number,  occupy  the  front 
and  back  of  the  forearm.  The  posterior  ulnar  cutaneous  vein3  com- 
mences from  the  outer  portion  of  the  back  of  the  hand,  ascends  along 
the  ulnar  border  of  the  back  of  the  forearm,  communicating  in  its  course 
with  anastomotic  branches  of  the  radial  cutaneous  vein,  and  at  the  bend 
of  the  elbow  assumes  the  name  of  basilic  vein.  The  anterior  ulnar 

1  V.  subclavia. 

2  V.  ulnares  cutaneae ;  v.  ulnaris  cutanea ;  v.  basilica. 

3  V.  ulnaris  cutanea  posterior ;  v.  salvatella. 

27 


418 


THE  VASCULAR  SYSTEM. 


FIG.  273. 


cutaneous  vein1  commences  in  front 
of  the  wrist,  ascends  along  the  fore- 
arm, anastomosing  in  its  course  with 
the  preceding,  and  either  terminates 
by  joining  the  posterior  ulnar  cuta- 
neous vein  or  the  median  vein. 

SUPERFICIAL  VEINS  OF  THE  UPPER  EXTREMITY.  1, 
median  vein;  2,  3,  radial  cutaneous  veins;  4,  5,  ul- 
nar cutaneous  veins;  6,  median-cephalic  vein;  7, 
median-basilic  vein ;  8,  anastomosis  with  the  deep 
veins;  9,  cephalic  vein  ;  10,  its  further  course  seen 
through  the  brachial  fascia;  11, 12,  basilic  vein. 

The  Basil'ic  vein2  ascends  from 
the  posterior  ulnar  cutaneous  vein 
along  the  inner  border  of  the  bi- 
ceps muscle,  and  perforates  the 
brachial  fascia,  to  join  above  the 
•middle  of  the  arm  one  of  the  bra- 
chial veins. 

The  Radial  cuta'neous  veins 
commences  from  the  radial  side  of 
the  back  of  the  hand,  ascends  along 
the  outer  border  of  the  forearm,  re- 
ceiving in  its  course  many  branches 
from  the  front  and  back  of  the 
latter,  and  at  the  bend  of  the  elbow 
assumes  the  name  of  cephalic  vein. 
Sometimes  there  are  two  radial 
cutaneous  veins  which  either  con- 
join near  the  bend  of  the  elbow,  or 
the  anterior  one  joins  the  median 
vein. 

The  Cephal'ic  vein,4  ascending 
from  the  former  along  the  outer 
border  of  the  biceps  muscle,  and 
then  in  the  groove  between  the 
deltoid  and  great  pectoral  muscles, 
dips  inwardly  below  the  clavicle 
and  terminates  in  the  axillary  vein. 


1  V.  ulnaris  cutanea  anterior. 

2  V.  basilica;  v.  cutanea  cubitalis; 
cubiti  interior. 


3  V.  radialis  cutanea ;  v.  cephalica. 
*  V.  cephalica ;    v.  cutanea  radialis 
r.  capitis. 


THE  VASCULAR  SYSTEM.  419 

The  Me'dian  veins1  occupy  the  front  of  the  forearm  in  the  interval  of 
the  ulnar'and  radial  cutaneous  veins,  with  which  they  freely  anastomose. 
They  are  very  variable  in  number,  arrangement,  and  method  of  termina- 
tion. Frequently  they  collect  into  a  parent  stem2  which  forks  at  the 
bend  of  the  arm — one  division,  named  the  median-cephalic  vein,3  pro- 
ceeds obliquely  upward  and  outward  to  join  the  cephalic  vein,  while 
the  other,  named  the  median-basiFic  vein,4  passes  upward  and  inward 
to  join  the  basilic  vein.  At  other  times  the  median  vein  or  veins  term- 
inate in  an  oblique  vessel  proceeding  across  the  bend  of  the  arm  upward 
and  inward  from  the  radial  cutaneous  vein  to  the  basilic  vein.  The 
middle  of  the  oblique  vessel  or  the  angle  of  the  forked  median  vein  anas- 
tomoses at  the  bend  of  the  arm  with  the  brachial  veins. 

The  median-basilic  vein  or  the  inner  portion  of  the  oblique  vessel  is 
larger  than  the  median-cephalic  vein,  and  is  usually  chosen  in  the  opera- 
tion of  bleeding  from  the  arm.  It  crosses  the  brachial  artery,  from 
which  it  is  only  separated  by  the  offset  from  the  tendon  of  the  biceps 
muscle  to  the  brachial  fascia.  Important  branches  of  the  internal  cuta- 
neous nerve  pass  above  and  below  it. 

THE  AZYGOS  VEIN. 

The  Az'ygos  vein5  commences  on  the  right  side  of  the  vertebral  col- 
umn, in  an  anastomotic  communication  with  the  lumbar  veins,  the  renal 
vein,  or  the  inferior  cava.  Passing  from  the  abdomen  through  the  aortic 
orifice  of  the  diaphragm,  or  through  a  distinct  aperture  in  the  right  crus 
of  the  latter,  it  ascends  on  the  dorsal  vertebra  and  arches  forward  over 
the  root  of  the  right  lung  to  terminate  in  the  superior  cava.  To  its 
ptgbfc  are  situated  the  thoracic  duct,  the  aorta,  and  the  oesophagus,  and 
in  its  course  it  receives  the  following  branches  : — 

The  Right  intercostal  veins,  Sometimes  the  upper  two  or  three  con- 
join in  a  trunk,  which  opens  into  the  right  innominate  vein. 

The  Oesophageal  veins. 

The  Right  bronchial  vein. 

The  Hemi-az'ygos  veins,  of  which  there  are  two  situated  on  the  left 
side  of  the  vertebral  column.  The  inferior  hemi-az'ygos  vein6  arises 
in  the  same  manner  as  the  azygos  vein,  and  like  it  enters  the  thorax, 
when  it  ascends  to  about  the  middle  of  the  dorsal  vertebrae,  and  then 

1  V.  medianae  ;  v.  mediana.  5  V.  azygos  ;  v.  azyga ;  v.  sine  pari ; 

2  V.  mediana  communis.  v.  pari  careus ;  v.  prelombo-thoracica. 

3  V.  mediana  cephalica.  6  v.  hemi- azygos;  v.  hemi-azyga;   v. 

4  V.  mediana  basilica.  azygos  sinistra,  or  parva. 


420 


THE   VASCULAR   SYSTEM. 


crosses  the  column  beneath  the  aorta  to  join  the  azygos  vein.  It  re- 
ceives in  its  course  the  lower  five  or  six  left  intercostal  veins,  The  supe- 
rior hemi-az'ygos  vein1  is  formed 
by  the  union  of  the  upper  left  in- 
tercostal veins  which  do  not  join 
the  former.  It  terminates  in  the 
left  innominate,  the  inferior  herni- 
azygos,  or  the  azygos  vein. 

THE  INFERIOR  CAY  A. 

The  Inferior  cava,2  the  ascend- 
ing trunk  of  the  venous  system, 
collects  the  blood  from  the  inferior 
extremities,  pelvis,  and  abdomen. 
It  commences  by  the  confluence  of 
the  common  iliac  veins  at  the  side 
of  the  fourth  lumbar  vertebra,  as- 
cends upon  the  vertebral  column  to 
the  right  of  the  aorta,  and  passes 
through  the  quadrate  foramen  of 
the  diaphragm  to  terminate  in  the 
right  auricle  of  the  heart.  It  is 
larger  than  the  aorta  or  the  supe- 
rior cava,  and  is  possessed  of  no 
valves.  Exclusive  of  the  common 
iliac  veins,  in  its  course  it  receives 
a  number  of  branches. 

BRANCHES  OF  THE  INFERIOR 
CAYA. 

The  Middle  sacral  vein3  follows 
the   course   of  the   corresponding 
VEINS  OF  THE  THORAX  AND  ABDOMEN,  i,  inferior     artery,  and  opens   into   the  com- 

cava;  2,  right,  3  left  renal  veins;  4,  superior  cava;  ,         .     „     . 

5,  right  6  left  innominate  veins;  7,  internal  veins;  mencement     of     the     inferior     Cava. 

8,  external  jugular  veins;  9,  subclavian  vein;  10,  Sometimes  it  terminates  in  the  left 
azygos  vein;  11  inferior,  12  superior  hemiazygos 

common  iliac  vein. 


i  V.  hemi-azygos  superior ;    superior 
intercostal  vein;  v.  semi-  or  demi-azygos. 


2  Cava  inferior ;    vena  cava  inferior, 
ascendens,  or  abdominalis ;  v.  hepatites. 

3  V.  sacralis  media. 


THE   VASCULAR   SYSTEM.  421 

The  Lumbar  veins1  are  three  or  four  in  number  on  each  side,  and 
follow  the  like-named  arteries.  They  anastomose  with  one  another,  and 
with  the  common  iliac,  azygos,  and  hemi-azygos  veins,  thus  forming  a 
plexus.2 

The  Spermatic  veins3  derive  their  blood  from  the  testicles.  Each 
originates  in  the  spermatic  plexus,4  and  follows  the  corresponding 
artery — the  right  one  to  terminate  in  the  inferior  cava,  the  left  one  in 
the  left  renal  vein. 

The  Ova'rian  veins,5  of  the  female,  originate  in  the  ovarian  plexus 
contained  in  the  broad  ligament,  and  follow  the  same  course  as  the  pre- 
ceding veins. 

The  Re'nal  veins6  are  short,  capacious  trunks,  formed  by  the  converg- 
ence of  several  branches  emerging  from  the  sinus  of  the  kidneys.  They 
are  nearly  transverse  in  their  direction,  and  the  left  one  is  the  longer, 
and  crosses  in  front  of  the  aorta  to  reach  its  destination. 

The  Supra-renal  veins7  consist  of  several  branches  from  the  supra- 
renal bodies  terminating  in  the  inferior  cava,  the  renal  veins,  and  those 
succeeding. 

The  Phren'ic  veins8  consist  of  two  companions  for  each  correspond- 
ing artery,  and  terminate  in  the  inferior  cava  just  below  the  following. 

The  Hepat'ic  veins9  are  two  or  three  trunks  which  emerge  from  the 
posterior  notch  of  the  liver,  and  immediately  terminate  in  the  inferior 
cava,  just  as  it  enters  the  quadrate  foramen  of  the  diaphragm. 

THE  PORTAL  VEIN. 

The  Portal  vein10  is  a  short,  capacious  trunk,  about  three  inches  in 
length,  derived  from  the  convergence  of  the  veins  of  the  stomach,  the 
small  and  large  intestines,  the  spleen,  and  the  pancreas.  It  commences 
by  the  conjunction  of  the  splenic  and  superior  mesenteric  veins  behind 
the  pancreas,  and  ascends  in  the  right  border  of  the  lesser  omentum  to  the 
transverse  fissure  of  the  liver,  where  it11  divides  into  two  principal  branches, 

1  V.  lumbares.  8  V.  phrenicse ;  v.  p.  inferiores ;  v.  dia- 

2  Plexus  lumbaris  et  v.  lumbaris  ad-       phragmaticae. 

scendens.  9  V.  hepaticae  ;   v.  cavae  hepaticae  ;   v. 

3  V.  spermaticae  ;   v.  s.  internae.  supra-hepaticae. 

4  Plexus  spermaticus ;  p.  pampinifor-  10  V.  portalis,  porta,  portae,  portarum, 
mis.  or  ad  portas  ;  v.  lactea ;  v.  arterialis ;  v. 

5  V.  ovariae.  ostiaria  ;    v.  magna;  manus  jecoris    or 

6  V.  renales;  v.  emulgentes.  hepatis;  ramalis  vena;  janitrix;  portal 

7  V.  supra-renales  ;  v.  capsulares ;  v.  system ;  abdominal  venous  system ;  sys- 
atrabiliariae.  tern  of  the  vena  porta. 

11  Sinus  venae  portarum. 


422 


THE  VASCULAR  SYSTEM. 


which  diverge  right  and  left  to  be  distributed  throughout  the  organ. 

The  blood  thus  conveyed 

Fl     275  to  the  liver,  together  with 

that  of  the  hepatic  artery, 
is  returned  to  the  general 
system  by  means  of  the 
hepatic  veins. 

The  Splenic  vein1  is 
derived  from  branches  cor- 
responding with  those  of 
the  splenic  artery,  and 
pursues  the  same  course 
as  this  until  it  joins  the 
portal  vein. 

The  Superior  mes'en- 
teric  vein2  pursues  the 
same  course  as  the  like- 
named  artery,  and  joins 
with  the  preceding  vein 
to  form  the  portal  vein. 

The  Cor'onary  vein3  of 
the  stomach  terminates 
either  in  the  splenic  vein 
or  the  portal  vein. 

The  Right  Gastro- 
epip'loic  vein4  joins  the 
superior  mesenteric  vein 
or  the  portal  vein. 

The  Cystic  vein,5  from 
the  gall-bladder,  joins  the 
latter  vessel. 

The  Inferior  Mes'enteric  vein,6  pursuing  the  course  of  the  corre- 
sponding artery,  terminates  in  the  splenic  or  the  superior  mesenteric 
vein. 

The  portal  vein  and  its  branches  are  destitute  of  valves. 


THE  PORTAL  SYSTEM  OF  VEixs.  a,  portal  vein ;  6,  splenic  vein ; 
c,  right  gastro-epiploic  vein;  d,  inferior  mesenteric  vein;  e.  supe- 
rior mesenteric  vein ;  f,  trunk  of  the  superior  mesenteric  artery. 
1,  liver ;  2,  stomach ;  3,  spleen ;  4,  pancreas ;  5,  duodenum ;  6,  as- 
cending colon :  the  transverse  colon  is  removed ;  7,  small  intestine ; 
8,  descending  colon. 


1  V.  splenica ;  v.  lienalis. 

2  V.  mesenterica  superior ;   v.  mesen- 
terica;  v.  m.  magna. 

3  V.  coronaria ;  v.  gastrica  superior. 


*  V.  gastro-epiploica  dextra ;  v.  gastri- 
ca dextra  inferior. 

5  V.  cystica. 

6  V.  mesenterica  inferior ;  v.  m.  minor ; 
v.  colica  sinistra. 


THE  VASCULAR  SYSTEM.  423 


THE  VEINS  OF  THE  VERTEBRAL  COLUMN. 

The  Dorsi-spinal  plexus1  is  a  net-work  of  veins  embracing  the  verte- 
bral arches  and  their  processes  posteriorly.  It  receives  the  veins  from 
the  muscles  of  the  back,  and  communicates  by  frequent  anastomoses  with 
the  intra-spinal  plexus,  the  vertebral,  intercostal,  lumbar,  and  sacral 
veins,  and  the  superficial  veins  of  the  back. 

The  Intra-spinal  plexus2  is  an  intricate  net-work  of  veins,  situated 
within  the  spinal  canal,  between  the  dura  mater  and  the  vertebras.  It  is 
composed  of  four  longitudinal  veins,  two  in  front  and  two  behind,  ex- 
tending the  entire  length  of  the  spinal  canal,  and  frequently  communi- 
cating with  one  another  by  transverse  veins.  The  anterior  longitudinal 
veins3  occupy  the  sides  of  the  vertebral  bodies  and  present  a  festooned 
appearance  from  their  curving  round  the  abutments  of  the  vertebral 
arches.  Opposite  the  vertebral  bodies  they  are  associated  by  transverse 
veins,  which  pass  beneath  the  vertebral  ligament  and  receive  the  diploic 
veins4  from  the  interior  of  the  vertebra.  The  posterior  longitudinal 
veins,5  smaller  than  the  anterior,  occupy  the  sides  of  the  vertebral 
arches,  and  conjoin  by  transverse  branches  crossing  the  latter,  and  like- 
wise join  the  anterior  longitudinal  veins  by  lateral  branches.  The  com- 
plexity of  the  intra-spinal  plexus  is  increased  by  frequent  division  and 
reunion  of  both  the  longitudinal  and  transverse  veins  as  they  pursue 
their  course. 

The  intra-spinal  plexus  receives  veins6  from  the  spinal  cord  and  its 
membranes,  and  communicates  through  the  intervertebral  foramina  with 
the  vertebral,  intercostal,  lumbar,  and  sacral  veins,  and  with  the  occipital 
sinuses  of  the  cranium. 

THE  COMMON  ILIAC  VEINS. 

The  Common  Il'iac  veins7  are  formed  by  the  confluence  of  the  inter- 
nal and  external  iliac  veins  opposite  the  sacro-iliac  articulation.  Con- 

1  Venae  dorsi-spinales ;  plexus  spinalis      rieures,  Breschet ;  sinus  columnae  verte- 
posterior ;  p.  spinales  extern!  posteriores;       bralis. 

plexus    rachidian     extern!    posterieur,  4  Venae  basi-vertebrales ;  v.  basis  ver- 

Breschet.  tebrarum. 

2  Plexus  spinalis  internus ;  p.  spinales  5  V.  longitudinales  posteriores  ;  plexus 
interni ;  p.  s.  i.  anteriores  et  posteriores ;  spinales   interni   posteriores ;    posterior 
veines  intra-rachidiennes  fr. ;  meningo-  spinal  veins ;  veines  longitudinales  ra- 
rachidian  veins.  chidiennes  posterieures,  Breschet. 

3  V.  longitudinales  anteriores ;    sinus  6  Medulli-spinal  veins ;    v.   medulli- 
longitudinales ;     plexus     longitudinales  spinales. 

anteriores;  great  spinal  veins;   grandes          7  V.  iliacae  communes;  v.  i.  primitivae. 
veines  rachidieunes  longitudinales  ante- 


424  THE   VASCULAR   SYSTEM. 

verging,  they  ascend  and  pass  beneath  the  right  common  iliac  artery, 
and  to  the  right  of  the  median  line,  on  the  last  lumbar  vertebra,  unite 
to  form  the  inferior  cava. 

The  right  vein  is  shorter  and  more  vertical  in  its  ascent  than  the  left ; 
and  is  at  first  behind  the  corresponding  artery,  and  then  gets  to  its  outer 
side.  The  left  vein  is  situated  at  the  lower  part  of  the  inner  side  of  its 
accompanying  artery.  Both  are  destitute  of  valves. 

THE  INTERNAL  ILIAC  Y^IN. 

The  Internal  Il'iac  vein1  corresponds  in  its  arrangement  with  the  dis- 
tribution of  the  like-named  artery,  posteriorly  to  which  it  is  situated, 
ascending  on  a  line  with  the  sacro-iliac  articulation  to  terminate  in  the 
common  iliac  vein.  It  receives  the  double  companion  veins  of  the  glu- 
teal,  ilio-lumbar,  lateral  sacral,  obturator,  and  ischiatic  arteries,  which 
generally  conjoin  with  each  other  shortly  before  terminating  in  the  main 
trunk. 

The  ilio-lumbar  veins  anastomose  with  the  lateral  sacral  and  lumbar 
veins,  and  frequently  terminate  in  the  common  iliac  vein.  The  lateral 
sacral  veins  form  with  the  middle  ones  a  plexus,2  which  communicates 
with  the  haemorrhoidal  plexus. 

The  veins  of  the  rectum,  bladder,  and  organs  of  generation  are  ex- 
ceedingly numerous  and  large,  and  in  several  positions  form  very  intri- 
cate and  capacious  plexuses. 

The  Haemorrlioid'al  plexus3  embraces  the  rectum,  and  is  especially 
well  developed  at  the  lower  part  of  the  latter,  where  it  is  the  frequent 
seat  of  varicose  enlargements,  constituting  haemorrhoids  or  piles.  It 
communicates  with  the  sacral  and  prostatic  plexuses ;  and  veins4  proceed 
from  it  to  the  inferior  mesenteric  vein,  the  internal  iliac  veins,  and  the 
pudic  veins. 

The  Prostat'ic  plexus5  is  an  intricate  and  capacious  net-work  of  veins, 
embracing  the  membranous  portion  of  the  urethra,  the  neck  of  the 
bladder,  the  prostate  body,  and  the  seminal  vesicles.  It  communicates 
freely  with  the  vesical  plexus,  joins  the  ha3morrhoidal  plexus,  and  termi- 
nates in  the  internal  iliac  and  pudic  veins. 

The  U'tero-vag'inal  plexus6  corresponds  in  the  female  with  the  pre- 
ceding, and  embraces  the  vagina  and  uterus.  It  communicates  with  the 

1  V.  iliaca  interna ;  v.  hypogastrica.  5  P.  prostaticus ;  p.  pudendalis  ;  part 

2  Plexus  sacralis.  of  vesico-prostatic  plexus. 

3  P.  hsemorrhoidalis.  6  P.  utero-vaginalis ;   p.  uterinus  et  p. 
*  V.  hsemorrhoidales  sup.  med.  et  inf. ;  vaginalis. 

v.  h.  internae  et  externae. 


THE  VASCULAR  SYSTEM.  425 

ovarian  and  the  pudic  veins,  and,  by  means  of  the  so-called  uterine 
veins,1  joins  the  internal  iliac  veins.  During  pregnancy,  the  veins  of 
the  uterine  plexus  become  exceedingly  enlarged,  forming  capacious 
sinuses,2  but  they  do  not  pursue  a  tortuous  course  like  the  arteries. 

The  Ves'ical  plexus3  embraces  the  bladder,  but  is  especially  well  de- 
veloped at  the  fundus  of  the  latter,  where  it  joins  the  prostatic  or  vaginal 
plexus.  From  it  proceed  several  vesical  veins  to  terminate  in  the  inter- 
nal iliac  veins. 

The  Pu'dic  vein4  pursues  the  course  of  the  corresponding  artery,  and 
is  formed  of  branches  which  accompany  the  deep  arteries  of  the  penis 
and  those  of  the  perineum.  It  communicates  with  the  prostatic  and 
hsemorrhoidal  plexuses,  and  terminates  in  the  internal  iliac  vein.  It  has 
a  corresponding  origin,  in  the  female,  from  the  clitoris  and  perineum, 
and  communicates  with  the  vaginal  plexus. 

Larger  veins  than  those  which  follow  the  deep  arteries  of  the  penis 
emerge  from  its  erectile  tissue  to  pursue  a  different  course.  Those  from- 
the  spongy  body  issue  at  the  base  of  the  glans  and  converge  to  form  the 
Dorsal  vein  of  the  penis,5  which  runs  along  the  dorsal  groove  of  the 
organ  beneath  the  arch  of  the  pubis.  After  perforating  the  triangular 
ligament,  it  divides  into  two  branches,  which  terminate  in  the  prostatic 
plexus.  The  veins  from  the  cavernous  bodies  emerge  at  the  lower  groove 
and  turn  round  their  outer  side  to  join  the  dorsal  vein.  The  Dorsal  vein 
of  the  clitoris6  has  a  corresponding  origin  and  course  as  the  preceding, 
and  terminates  in  like  manner  in  the  vaginal  plexus. 

THE  EXTERNAL  ILIAC  VEINS. 

The  External  Il'iac  vein7  collects  the  blood  from  the  lower  extremity, 
and  is  the  continuation  of  the  femoral  vein.  Commencing  beneath  Pou- 
part's  ligament  at  the  inner  side  of  the  corresponding  artery,  it  ascends 
behind  the  latter  to  join  with  the  internal  iliac  in  the  formation  of  the 
common  iliac  vein.  At  its  commencement  it  receives  the  double  com- 
panion veins  of  the  circumflex  iliac  and  epigastric  arteries. 

1  V.  uterinse.  4  V.  pudica. 

a  Uterine  sinuses.  5  y.  dorsalis  penis. 

3  P.  vesicalis  ;  part  of  vesico-prostatic  6  V.  dorsalis  clitoridis. 

plexus.  <  V.  iliaca  externa. 


426  THE  VASCULAR   SYSTEM. 


THE  DEEP  VEINS  OF  THE  LOWER  EXTREMITY. 

The  Deep  veins  of  the  lower  extremity  pursue  the  exact  course  of 
the  corresponding  arteries ;  every  one  of  these,  excepting  the  popliteal 
artery  and  its  continuation  the  femoral  having  two  companions  which 
anastomose  with  each  other  across  the  vessel  they  accompany. 

The  Poplite'al  vein,1  formed  by  the  conjunction  of  the  companion 
veins  of  the  anterior  and  posterior  tibial  arteries,  is  situated  behind  the 
corresponding  artery,  and  passes  in  company  with  it  through  the  perfo- 
ration of  the  great  adductor  muscle  to  assume  the  name  of  femoral  vein. 

The  Fem'oral  vein2  at  first  lies  behind  its  accompanying  artery,  but 
gradually  inclines  to  the  inner  side  during  its  ascent,  and  at  Poupart's 
ligament  assumes  the  name  of  external  iliac  vein. 

THE  SUPERFICIAL  VEINS  OF  THE  LOWER  EXTREMITY. 

The  Superficial  veins  of  the  lower  extremity  have  the  general  plexi- 
form  arrangement,  relation  of  position  to  the  skin,  and  other  characters 
indicated  in  the  account  of  those  of  the  upper  extremity.  Two  princi- 
pal trunks,  the  saphenous  veins,  collect  the  blood  of  the  superficial  veins 
and  empty  it  into  the  main  trunk  of  the  deep  veins. 

The  Short  saphe'nous  vein3  proceeds  from  branches  along  the  outer 
part  of  the  back  of  the  foot,  passes  behind  the  outer  ankle,  ascends  the 
back  of  the  leg,  and  dips  between  the  heads  of  the  gastrocnemius  mus- 
cle to  terminate  in  the  popliteal  vein.  It  collects  the  blood  of  the  super- 
ficial veins  of  the  outer  part  of  the  foot,  and  the  outer  and  back  part  of 
the  leg,  and  anastomoses  freely  with  branches  joining  the  succeeding 
vein. 

The  Long  saphe'nous  vein,4  more  capacious  than  the  other,  springs 
from  branches  on  the  back  and  inner  side  of  the  foot.  Passing  in 
front  of  the  inner  ankle,  it  ascends  along  the  tibia  to  the  knee,  where 
it  inclines  backward,  and  then  ascends  upon  the  thigh  to  the  saphenous 
opening.  Through  this  it  dips  to  terminate  in  the  femoral  vein.  It  re- 
ceives the  veins  from  the  inner  side  of  the  foot,  the  greater  number  of 
those  of  the  leg,  all  those  of  the  thigh,  the  external  pudic  veins,  and 
many  of  those  of  the  abdomen. 

1  V.  poplitea.  4  V.  s.  longa;   v.  saphena  interim;  v. 

2  V.  femoralis ;  v.  cruralis.  s.  magna ;    v.  tibio-malleolaris ;    great 

3  V.  saphena  parva ;  v.  s.  externa ;  v.  saphena  vein ;  internal  saphenous  vein, 
pereneo-malleolaris ;  lesser  saphena  vein ; 

external  saphenous  vein. 


FIG.  276. 


THE  VASCULAR  SYSTEM. 

FIG.  277. 


427 


Fig.  276.  SUPERFICIAL  VEINS  OF  THE  BACK  OF 
THE  LEG.  1,  short  saphenous  vein ;  2,  position 
at  which  it  terminates  in  the  popliteal  vein;  3, 
long  saphenous  vein. 

Fig.  277.  SUPERFICIAL  VEINS  OF  THE  INNER 

PART  OF  THE  LOWER  EXTREMITY.     1,  long  Saphe- 

notis  vein ;  2,  its  termination  at  the  saphenous 
opening  into  the  femoral  vein. 


428  THE   VASCULAR  SYSTEM. 

THE  PULMONAEY  YEINS. 

The  Pulmonary  veins  are  four  short  venous  trunks,  of  which  two 
emerge  from  each  lung  and  convey  bright-red  blood  to  the  heart. 

The  Right  Pulmonary  veins,  longer  than  those  of  the  left  side,  pass 
from  the  root  of  the  right  lung,  below  the  corresponding  pulmonary 
artery,  behind  the  superior  cava,  the  right  auricle  and  the  aorta,  to  term- 
inate in  the  left  auricle. 

The  Left  Pulmonary  veins  pass  from  the  left  lung  in  front  of  the  de- 
scending aorta,  and  likewise  terminate  in  the  left  auricle. 

THE  LYMPHATIC  SYSTEM. 

The  Lymphat'ic  System1  consists  of  vessels,  gland-like  bodies,  and  a 
contained  liquid.  The  former  are  named  lymphatic  vessels  or  lym- 
phatics ;  the  gland-like  bodies  are  called  lymphatic  glands,  or,  together 
with  the  vessels,  are  also  named  lymphatics.  The  contained  liquid  of 
both  vessels  and  glands  is  the  lymph. 

The  intestinal  lymphatics  are  more  commonly  known  as  the  lacteals, 
and  their  contained  liquid  as  the  chyle. 

Lymphatic  vessels2  exist  in  mammals,  birds,  reptiles,  and  fishes,  but 
are  absent  in  the  lower  classes  of  animals.  They  are  found  in  most  tis- 
sues and  organs  which  receive  blood,  but  have  not  been  detected  in  the 
substance  of  the  brain  and  spinal  cord,  in  the  eyeball  and  labyrinth,  nor 
the  placenta  and  its  membranes. 

The  lymphatics  are  accessory  to  the  sanguiferous  system.  From  the 
various  tissues  and  organs  they  collect  a  liquid  which  is  apparently  a 
transuded  portion  of  the  liquor  sanguinis  unappropriated  by  the  tissues. 
In  addition,  they  collect  nutritive  material  derived  from  the  food  in 
the  intestines.  The  liquids  thus  obtained  are  conveyed  from  smaller  to 
larger  vessels,  traversing  in  their  course  the  lymphatic  glands,  until 
finally  they  collect  into  two  great  trunks,  the  thoracic  duct  and  the  right 
lymphatic  duct,  which  empty  the  lymph  into  the  veins. 

The  lymphatics  consist  of  a  deep  and  superficial  set,  the  former  follow- 
ing the  course  of  the  deeply-seated  blood-vessels,  and  the  latter  running 
beneath  the  skin  and  the  membranous  envelopes  of  the  organs  in  which 
they  exist. 

The  principal  lymphatic  vessels  are  more  numerous  than  the  arteries 
and  veins,  but  are  very  much  finer.  They  are  long,  thread-like,  trans- 

1  Absorbent  system. 

2  Absorbent  vessels,  or  absorbents ;   vasa  lymphatica ;   venae  lymphatics ;   vasa 
resorbentia;  v.  hydragoga;  ductus  serosi ;  lymphae-ductus ;  lymphangia;  hydrangia. 


THE   VASCULAR   SYSTEM. 


429 


FIG.  278. 


parent  tubes,  of  difficult  detection  unless  some  colored  substance  is  in- 
jected into  them.  They  are  remarkable  also  for  their  great  number  of 
valves,  which  are  constructed  like  those  of  the  veins,  and  prevent  a  retro- 
grade course  of  the  lymph.  The  valves  are  arranged  in  pairs  at  short 
distances  apart,  and  the  vessels  behind  them  are  dilated  so  that  they  pre- 
sent a  beaded  appearance  when  distended. 

The  mode  in  which  the  lymphatics  commence  has  been  imperfectly 
ascertained  in  consequence  of  the  extreme  tenuity  and  transparency  of  the 
vessels  and  the  impossibility  of  in- 
jecting colored  liquids  in  a  direction 
opposed  to  the  opening  of  the  many 
valves  which  occupy  the  larger 
branches.  For  the  most  part  they 
appear  to  originate  in  close  capillary 
nets,  intercalated  with  the  sanguifer- 
ous  capillaries,  but  having  no  com- 
munication with  them.  In  the  villi 
of  the  intestines  the  capillary  lym- 
phatics apparently  commence  as 
single  club-like  tubes  with  the  ex- 
tremity closed.  The  lymphatic  ca- 
pillaries are  even  larger  than  the 
sanguiferous  capillaries,  and  like 
them  are  destitute  of  valves. 

Nearly  all  the  principal  lym- 
phatic vessels,  in  their  course  to 
the  great  trunks,  pass  through  lym- 
phatic glands  which  occupy  convenient  positions  in  the  various  recesses 
and  cavities  of  the  body.  As  they  approach  near  to  the  glands,  they 
divide  and  subdivide  before  entering  the  latter,  and  in  emerging  at  the 
opposite  side  many  branches  converge  to  form  larger  vessels.  Those 
which  enter  are  named  afferent  vessels,1  and  those  which  emerge  are  the 
efferent  vessels,2  and  are  fewer  and  larger  than  the  former. 

In  structure  the  lymphatic  vessels  resemble  the-  blood-vessels,  more 
especially  the  veins.  According  to  Kolliker,  their  external  coat  con- 
tains longitudinal  bundles  of  muscular  fibres. 

The  Lymphatic  glands3  are  moderately  hard,  pinkish  bodies,  varying 
in  size  from  that  of  a  hemp-seed  to  that  of  an  almond,  and  are  mostly 


LYMPHATIC  CAPILLARY  NET-WORK  OF  THE  SKIN  OP 
THE  EAR. 


1  Vasa  afferentia ;  v.  inferentia.  2  Vasa  efferentia. 

3  Lymphatic  ganglions ;  conglobate,  or  globate  glands ;    glandulae  lymphatic® ; 
g.  conglobatae. 


430  THE   VASCULAR  SYSTEM. 

compressed  spheroidal  or  ovoidal.  They  are  generally  situated  along  the 
course  of  the  larger  blood-vessels,  and  exist  in  considerable  numbers 
within  the  thorax  and  abdomen,  but  likewise  are  found  in  the  neck,  the 
axilla,  groin,  bend  of  the  elbow,  and  the  popliteal  space. 

The  structure  of  the  lymphatic  glands  has  not  yet  been  positively 
demonstrated.  According  to  recent  investigations,  they  appear  to  con- 
sist of  a  multitude  of  vesicles  or  pouches  which  communicate  with  one 
another,  with  the  termination  of  the  afferent  vessels,  and  with  the  com- 
mencement of  the  efferent  vessels.  The  vesicles  occupy  the  interspaces 
of  a  stroma  of  connective  tissue  abundantly  supplied  with  blood-vessels. 
In  constitution  the  vesicles  resemble  those  which  form  the  solitary  and 
agminated  glands,  and  are  suspected  to  be  the  source  of  the  lymph  cor- 
puscles. 

Lymph1  possesses  nearly  the  same  physical  and  chemical  properties  as 
liquor  sanguinis.  After  passing  through  the  lymphatic  glands  it  is 
found  to  have  acquired  numerous  bodies,  named  lymph  corpuscles.2 
These  are  faintly  granular  nucleated  cells  like  the  colorless  corpuscles  of 
the  blood.  They  are  also  identical  in  character  with  the  nucleated  cells 
of  the  vesicular  structure  in  the  lymphatic  glands,  and  are  hence  inferred 
to  be  derived  from  the  latter.  A  few  corpuscles  of  the  same  kind  have 
been  noticed  in  the  intestinal  lymphatic  vessels  before  reaching  the  mes- 
enteric  glands,  and  are  suspected  of  originating  in  the  solitary  and  agmi- 
nated glands. 

From  the  researches  of  Wharton  Jones,  published  more  than  a  dozen 
years  ago,  the  lymph  corpuscles  ultimately  undergo  solution,  and  leave 
their  nuclei  transformed  into  blood  disks.  Though  these  researches  ap- 
pear to  be  but  little  noticed,  the  opinion  gains  ground  that  the  lymph 
corpuscles  constantly  poured  into  the  blood  are  the  source  of  its  red 
corpuscles. 

Chyle3  is  the  lymph  of  the  intestinal  canal  modified  by  admixture  of 
the  absorbed  nutritive  liquid  of  the  food.  From  the  presence  of  innu- 
merable fat  particles,  it  is  commonly  of  a  milk-white  color,  whence  the 
name  of  lacteals,4  given  to  the  lymphatic  vessels  which  convey  it  to  the 
thoracic  duct. 

THE  TRUNKS  OF  THE  LYMPHATIC  SYSTEM. 

The  lymphatic  system  has  two  main  trunks,  of  which  one  is  compara- 
tively long  and  large,  and  is  named  the  thoracic  duct,  while  the  other 
is  quite  small,  and  is  called  the  right  lymphatic  duct. 

iLympha;  white  blood.  4  Vasa  chylifera ;  chyliferous  vessels; 

2  Lymph  globules ;  white  corpuscles.        vasa  lactea. 

3  Chylus ;  succus  nutritius. 


THE  VASCULAR  SYSTEM. 


431 


THE  THORACIC  DUCT. 


VIEW    OP   THE   GREAT    LYMPHATIC    TRUNKS.     1,  2, 

thoracic  duct;  3,  its  termination  at  the  angle  of 
conjunction  of  the  left  internal  jugular  and  sub- 
clavian  veins;  4,  the  right  lymphatic  duct;  5, 
lymphatics  of  the  thigh;  6,  iliac  lymphatics;  7, 
lumbar  lymphatics ;  8,  intercostal  lymphatics,  a, 
superior  cava;  b,  left  innominate  vein;  c,  right  in- 
nominate vein ;  d,  aorta;  e,  inferior  cava;  /, psoas 
muscle ;  g,  origin  of  the  diaphragm. 

The  Thorac'ic  duct1  commences 
in  front  of  the  second  lumbar  ver- 
tebra, between  the  aorta  and  infe- 
rior cava,  through  the  union  of  the 
two  lumbar  lymphatic  trunks  with 
the  intestinal  lymphatic  trunk ;  the 
former  being  derived  from  the  lym- 
phatics of  the  pelvis  and  lower  ex- 
tremities, the  latter  from  the  vis- 
ceral lymphatics. 

The  intestinal  lymphatic  trunk 
alone,  or  in  conjunction  with  one 
or  both  of  the  lumbar  lymphatic 
trunks,  usually  forms  an  oblong  di- 
latation, called  the  Receptacle  of 
the  Chyle.2  This  dilatation  is  of 
variable  size,  but  generally  meas- 
ures from  one  to  two  inches  in 
length,  by  the  fourth  of  an  inch  in 
width 

After  its  origin,  the  thoracic 
duct  passes  through  the  aortic  ori- 
fice of  the  diaphragm,  and  ascends 
in  front  of  the  vertebral  column, 
between  the  aorta  and  azygos  vein, 
and  behind  the  oesophagus.  From 


FIG.  279. 


1Ductus  thoracicus;  d.  t.  posterior;  d. 
lymphaticus  sinister ;  d.  rorifer ;  d.  ver- 
tebralis  ;  d.  chyli ;  d.  chyliferus  ;  d.  lac- 
teus ;  d.  Pecquetianus ;  vena  alba  thora- 
cis  Eustachii ;  distributoria  lactea  thora- 
cica ;  galaxia ;  duct  of  Pecquet ;  aliment- 
ary duct. 


2  Receptaculum  chyli ;  r.  Pecqueti ; 
cisterna  Pecqueti ;  c.  chyli ;  c.  lumbaris ; 
sacculus  lacteus,  chyliferus,  or  rorifer; 
diversorium,  stagnum,  vesicula,  or  am- 
pulla chyli;  utriculus  lacteus;  alveus 
ampullosus;  chylocistis;  chylodochium ; 
latices  lactei ;  reservoir  of  the  chyle,  or 
of  Pecquet. 


432  THE   VASCULAR  SYSTEM. 

the  position  of  the  fourth  dorsal  vertebra  it  inclines  to  the  left  side, 
passes  behind  the  arch  of  the  aorta,  and  ascends  between  the  oesophagus 
and  left  subclavian  artery,  as  high  as  the  last  vertebra  of  the  neck.  It 
then  curves  forward,  outward,  and  downward,  and  terminates  in  the 
angle  of  union  of  the  left  subclavian  and  internal  jugular  veins,  its 
orifice  being  protected  by  a  pair  of  valves,  which  prevent  the  entrance 
of  venous  blood. 

At  its  commencement  the  thoracic  duct  is  about  the  diameter  of  a 
goose-quill,  but  narrows  in  its  ascent  to  about  the  middle  of  its  course, 
when  it  widens  again — sometimes  becoming  in  a  marked  degree  dilated. 
It  is  not  straight,  but  slightly  tortuous ;  and  occasionally  subdivides, 
again  to  reunite.  It  is  provided  with  valves,  more  especially  in  the 
upper  part  of  its  course,  but  fewer  than  in  lymphatic  vessels  generally. 
It  receives  all  the  lymphatics  of  the  body  below  the  diaphragm,  those  of 
the  left  side  of  the  thorax,  head,  and  neck,  and  those  of  the  left  upper 
extremity. 

THE  RIGHT  LYMPHATIC  DUCT. 

The  Right  lymphatic  duct1  is  about  half  an  inch  in  length,  and 
about  a  line  in  width  ;  and  terminates,  in  a  corresponding  manner  with 
the  thoracic  duct,  on  the  right  side  of  the  body.  It  receives  the  lym- 
phatics of  the  right  side  of  the  head,  neck,  and  thorax,  and  those  of  the 
right  upper  extremity. 


LYMPHATICS  OF  THE  HEAD  AND  NECK. 

The  lymphatic  vessels  of  the  head  and  neck  from  particular  localities 
terminate  in  groups  of  glands,  from  which  efferent  vessels  proceed  to  the 
next  group  of  glands  below,  and  so  on  until  a  few  trunks  are  formed 
which  terminate  at  the  bottom  of  the  neck  in  the  thoracic  duct  and  the 
right  lymphatic  duct. 

LYMPHATICS   OF   THE    CRANIAL    CAVITY. 

No  lymphatic  vessels  have  been  detected  in  the  brain,  though  they  are 
numerous  in  the  pia  mater,  in  which  they  pursue  the  course  of  the  prin- 
cipal veins,  and  emerge  from  the  cranium  through  foramina  giving  pas- 
sage to  arteries  and  veins. 

1  Ductus  lymphaticus  dexter ;  d.  thoracicus  dexter ;  d.  t.  minor ;  truncus  lym- 
phaticus  dexter. 


THE   VASCULAR   SYSTEM. 


433 


LYMPHATICS   OP   THE   EXTERIOR   OP   THE   CRANIUM. 

The  occip'ital  lymphatic  vessels  are  derived  from  the  back  of  the 
head,  and  terminate  in  the  occip'ital  and  posterior  auric'ular  glands.1 
Of  these  there  are  four  or  five  small  ones  situated  in  the  Vicinity  of  the 
mastoid  process  on  the  sterno-mastoid  and  trapezius  muscles. 

FIG.  280. 


LYMPHATICS  OF  THE  HEAD  AND  NECK.  1,  facial  lymphatics;  2,  temporal  lymphatics;  3,  posterior  auric- 
ular and  occipital  lymphatics;  4,  cervical  lymphatics;  5,  the  right  lymphatic  duct;  6,  internal  jugular 
vein ;  7,  sub  lavian  vein. 

The  temporal  lymphatic  vessels  are  derived  from  the  side  of  the 

1  Glandulee  occipitales,  or  cervicales,  and  g.  auriculares  posteriores,  or  subauricu- 
lares,  or  mastoideae. 

28 


t 


434  THE   VASCULAR   SYSTEM. 

head,  and  terminate  in  the  anterior  auricular  glands,1  of  which  there 
are  two  or  three  situated  on  the  parotid  gland  in  front  of  the  ear. 

LYMPHATICS   OF    THE    FACE. 

The  superficial  fa'cial  lymphat'ic  vessels,  derived  from  the  forehead, 
eyelids,  nose,  lips,  cheek,  and  chin,  terminate  in  the  submax'illary  lym- 
phatic glands.2  Of  these  there  are  six  or  more,  situated  upon  the  sub- 
maxillary  salivary  gland,  from  which  they  also  receive  lymphatic  vessels. 

The  deep  fa'cial  lymphat'ic  vessels  are  derived  from  the  temporal 
fossa,  the  orbit,  the  cavity  of  the  nose,  the  palate,  the  side  of  the  mouth, 
the  upper  part  of  the  pharynx,  the  ear,  and  the  cranial  cavity.  They 
terminate  in  from  five  to  ten  internal  maxillary  glands,3  situated  at 
the  side  of  the  pharynx,  within  the  position  of  the  parotid  gland  and  the 
ramus  of  the  lower  jaw. 

The  lingual  lymphat'ic  vessels  follow  the  direction  of  the  lingual 
arteries  and  veins,  and  traverse  three  or  four  glands4  in  their  course. 

LYMPHATICS   OF    THE    NECK. 

The  superficial  cer'vical  lymphatic  vessels,  from  the  front  and  back 
of  the  neck,  together  with  the  efferent  vessels  of  the  occipital  and  poste- 
rior auricular  lymphatic  glands,  and  part  of  those  from  the  anterior 
auricular  and  submaxillary  lymphatic  glands,  terminate  in  the  superficial 
cer'vical  glands.5  Of  these  there  are  five  or  six  small  ones  situated  at 
the  upper  part  of  the  neck  on  the  sterno-mastoid  muscle,  or  at  its  poste- 
rior border. 

The  deep  cer'vical  lymphatics6  consist  of  a  chain  of  twenty  or  more 
glands7  pursuing  the  general  course  of  the  internal  jugular  vein  and 
carotid  artery.  They  communicate  with  the  axillary  lymphatics,  and  in 
their  course  receive  efferent  vessels  from  the  anterior  auricular  and  sub- 
maxillary  lymphatic  glands,  those  of  the  internal  maxillary,  lingual,  and 
superficial  cervical  lymphatic  glands,  and  the  lymphatic  vessels  of  the 
larynx,  pharynx,  thyroid  gland,  trachea,  oesophagus,  and  muscles  of  the 
neck. 

The  efferent  vessels  of  the  deep  cervical  lymphatic  glands  unite  in  the 
ju'gular  lymphatic  trunk,8  which  terminates  on  the  corresponding  side 
in  the  thoracic  duct,  or  the  right  lymphatic  duct. 

1  G.  auriculares  anteriores ;  g.  faciales  5  G.  cervicales   superficiales ;    plexus 
superficial ;  g.  zygomaticae.                          jugularis  externus. 

2  G.  submaxillares.  6  Plexus  jugularis  internus. 

3  G.  maxillares   internae ;    g.  faciales          7  G.  c.  profundse ;  g.  c.  p.  superiores 
profundae.  and  inferiores,  or  supra-claviculares. 

*  G.  linguales.  8  Truncus  1.  jugularis. 


THE   VASCULAR   SYSTEM.  435 

LYMPHATICS  OF  THE  UPPER  EXTREMITIES,  AND  OF  THE 
EXTERIOR  OF  THE  THORAX. 

The  lymphatics  of  the  upper  extremity  consist  of  a  superficial  and 
deep  series,  which  pursue  the  general  direction  of  the  corresponding 
arterial  and  venous  trunks. 

The  principal  superficial  lymphatic  vessels  in  ascending  the  upper 
extremity  are  directed  to  its  inner  side,  most  of  them  pursuing  the  course 
of  the  brachial  and  cephalic  veins.  In  front  of  the  internal  condyle  a 
few  of  them  traverse  a  lymphatic  gland;1  and  nearly  all  converge  to  enter 
the  lower  lymphatic  glands  of  the  axilla.  Some  of  them  accompanying 
the  cephalic  vein,  together  with,  others  from  the  shoulder,  join  the  axillary 
lymphatic  glands  below  the  clavicle,  or  communicate  with  those  of  the 
neck. 

The  deep  lymphatic  vessels  of  the  upper  extremity,  following  the 
direction  of  the  arteries  and  their  companion  veins,  after  traversing 
three  or  more  lymphatic  glands2  in  the  vicinity  of  the  elbow,  terminate 
in  the  axillary  lymphatic  glands. 

The  superficial  lymphatic  vessels  of  the  thorax  commence  beneath 
the  skin  of  the  upper  part  of  the  abdomen  and  breast.  The  deep  vessels 
are  derived  from  the  mammary  gland  and  the  pectoral  and  neighboring 
muscles.  Most  of  these  lymphatics  pass  outward  and  upward  to  the 
axillary  lymphatic  glands,  and  a  few  of  them  terminate  in  the  glands 
below  the  clavicle. 

The  axillary  glands,3  which  receive  the  lymphatic  vessels  of  the  upper 
extremity  and  exterior  of  the  thorax,  number  from  eight  to  a  dozen,  and 
are  enveloped  in  the  loose  areolar  tissue  and  fatty  matter  of  the  armpit. 
They  extend  from  the  lower  part  of  the  latter  to  the  clavicle,  and  com- 
municate with  the  deep  cervical  lymphatic  glands.  Their  efferent  vessels, 
following  the  direction  of  the  subclavian  vein,  unite  in  the  subcla'vian 
lymphatic  trunk,*  which  terminates  in  the  thoracic  duct,  or  the  right 
lymphatic  duct. 

LYMPHATICS  OF  THE  CAVITY  OF  THE  THORAX. 

The  intercos'tal  lymphatic  vessels  pursue  the  course  of  the  corre- 
sponding veins,  and  are  derived  from  the  sides  of  the  thorax  and 
abdomen,  the  diaphragm,  pleura,  muscles  of  the  back,  and  spinal  canal. 


1  G.  cubitalis  superficialis.  »  G.  axillares  and  g.  infra-claviculares. 

2  G.  cubitales  profundae  and  g.  hume-          *  Truncus  lymphaticus  subclavius. 
rales. 


436  THE  VASCULAR   SYSTEM. 

In  the  vicinity  of  the  heads  of  the  ribs  they  traverse  fifteen  or  more 
intercostal  glands,1  the  efferent  vessels  of  which  terminate  for  the  most 
part  in  the  thoracic  duct. 

Between  the  intercostal  lymphatic  glands  of  the  two  sides,  and  com- 
municating with  them,  there  are  about  a  dozen  posterior  medias'tinal 
glands,2  which  receive  lymphatic  vessels  from  the  diaphragm,  pericardium, 
and  oesophagus.  Some  of  the  efferent  vessels  of  these  glands  terminate 
in  the  thoracic  duct,  while  others  join  the  bronchial  lymphatic  glands. 

The  anterior  medias'tinal  lymphatic  vessels3  are  derived  from  the 
front  wall  of  the  abdomen,  the  upper  surface  of  the  liver  through  the 
suspensory  ligament,  the  front  wall  of  the  thorax,  the  diaphragm,  pericar- 
dium, heart,  and  thymus  gland.  They  traverse  about  twenty  anterior 
medias'tinal  glands,4  situated  in  the  course  of  the  internal  mammary 
blood-vessels,  on  the  pericardium,  and  in  front  of  the  great  blood-vessels 
emanating  from  the  base  of  the  heart.  Their  efferent  vessels  terminate 
in  the  thoracic  and  the  right  lymphatic  ducts. 

The  pulmonary  lymphatic  vessels  consist  of  a  superficial  and  deep 
series.  The  former  arise  from  an  intricate  net-work  beneath  the  pul- 
monary pleura,  and  are  directed  toward  the  root  of  the  lung,  where  they 
meet  the  deep  vessels.  These  pursue  the  ramifications  of  the  pulmonary 
blood-vessels  and  bronchi,  traversing  in  the  terminal  portion  of  their 
course  a  number  of  small  pulmonary  glands.5  At  the  bifurcation  of  the 
trachea,  on  the  bronchi,  and  at  the  root  of  the  lungs,  there  are  twenty  or 
more  bron'chial  glands,6  which  receive  the  lymphatic  vessels  of  the  lungs 
and  of  the  bronchi,  and  some  of  those  of  the  trachea,  oesophagus,  and 
heart.  These  glands  are  comparatively  large ;  in  infancy  have  the  same 
color  and  consistence  as  those  of  other  parts  of  the  body,  but  in  the  pro- 
gress of  life  gradually  assume  a  gray  and  finally  a  black  color,  arising 
from  a  deposit  of  fine  particles  of  pigmentary  matter.  They  also  fre- 
quently become  the  seat  of  calcareous  or  tubercular  deposits.  Their 
efferent  vessels  on  the  left  side  terminate  in  the  thoracic  duct,  but  on  the 
right  side  unite  to  form  the  broncho-medias'tinal  trunk,7  which  ascends 
behind  the  innominate  vein  to  join  the  right  lymphatic  duct. 

1  G.  intercostales.  5  G.  pulmonicae. 

2  G.  mediastinae  posteriores.  6  G.  bronchiales  and  tracheales ;  g.  Ve- 

3  Internal  mammary  lymphatic  vessels.  salianae. 

4  G.  mediastinae  anteriores  and  g.  ster-  '  Truncus  broncho-mediastinus. 
nales. 


THE   VASCULAR   SYSTEM.  437 


LYMPHATICS  OF  THE  LOWER  EXTREMITIES  AND  OF  THE 

PELVIS. 

The  superficial  lymphatic  vessels  originating  on  the  back  of  the  foot 
ascend  in  the  course  of  the  long  saphenous  vein  to  terminate  in  the 
superficial  inguinal  glands.  Those  originating  from  the  sole  of  the  foot 
accompany  the  short  saphenous  vein  and  partly  join  the  former  series ; 
while  others  terminate  in  the  popliteal  glands. 

The  deep  lymphatic  vessels  follow  the  course  of  the  corresponding 
blood-vessels,  traverse  from  two  to  four  poplite'al  glands1  in  their  course, 
and  finally  join  the  deep  inguinal  glands. 

The  superficial  in'guinal  glands,2  from  'six  to  a  dozen  in  number,  are 
situated  in  the  saphenous  opening  of  the  crural  fascia  and  extend  out- 
wardly in  the  groin.  Besides  receiving  the  superficial  lymphatic  vessels 
ascending  from  the  lower  extremity,  they  receive  the  superficial  lym- 
phatic vessels  of  the  lower  part  of  the  abdomen,  the  loins,  and  the  but- 
tocks, and  those  of  the  integument  of  the  penis  and  scrotum,  or  of  the 
clitoris  and  labia  in  the  female. 

The  deep  in'guinal  glands,3  of  which  there  are  two  or  three,  are  situ- 
ated upon  the  femoral  blood-vessels.  They  receive  the  deep  lymphatics 
of  the  lower  extremity,  and  communicate  with  the  superficial  glands. 

The  efferent  vessels  of  the  inguinal  glands  ascend  beneath  the  femoral 
arch  and  enter  a  chain  of  six  or  more  external  iliac  glands.4  These  are 
situated  in  the  course  of  the  corresponding  blood-vessels,  and  further  re- 
ceive lymphatic  vessels  from  the  front  and  side  of  the  abdomen  intern- 
ally. 

The  lymphatic  vessels  of  the  perineum,  of  the  penis  or  the  clitoris,  of 
the  back  portion  of  the  scrotum  or  labia,  of  the  bladder,  of  the  prostate 
gland  and  seminal  vesicles,  or  the  vagina  and  uterus,  of  the  muscles  of 
the  buttocks,  and  of  the  rectum,  converge  to  a  dozen  or  more  internal 
il'iac  glands.5  These  are  situated  at  the  side  of  the  pelvis,  about  the 
corresponding  blood-vessels,  and  communicate  with  the  glands  of  the  op- 
posite side  in  front  of  the  sacrum,  and  with  the  external  iliac  glands. 

1  G.  poplitese.  5  G.  iliacse  internae,  or  hypogastricae, 

2  G.  inguinales  superficiales.  and  g.  sacrales ;    plexus   hypogastricus 

3  G.  inguinales  profundce.  and  sacralis. 

4  G.  iliacae    externse ;    plexus   iliacus 
externus. 


438  THE   VASCULAR   SYSTEM. 


LYMPHATICS  OF  THE  CAVITY  OF  THE  ABDOMEN. 

The  efferent  vessels  of  the  external  and  internal  iliac  glands  become 
the  afferent  vessels  of  the  lumbar  glands.1  Of  these  there  are  about 
twenty-five  situated  on  each  side  of  the  vertebral  column  and  great 
blood-vessels,  upon  the  origin  of  the  diaphragm,  and  upon  the  psoas  and 
quadrate  lumbar  muscles.  The  glands  of  the  opposite  sides  freely  com- 
municate; and  besides  the  vessels  mentioned,  they  receive  lymphatic 
vessels  from  the  loins,  the  kidney  and  ureter,  the  supra-renal  body,  and 
the  testicle  or  the  ovary. 

The  efferent  vessels  of  the  lumbar  glands,  on  each  side  of  the  abdomen, 
conjoin  to  form  the  lumbar  lymphatic  trunk,2  frequently  represented  by 
several  smaller  ones,  terminating  in  the  thoracic  duct  or  the  receptacle 
of  the  chyle. 

The  lymphatic  vessels  of  the  stomach  pursue  the  direction  of  its 
blood-vessels,  traversing  in  their  course  a  number  of  small  glands.3 
Those  from  the  lesser  curvature  and  the  right  side  of  the  greater  curva- 
ture terminate  in  the  mesenteric  glands ;  those  from  the  left  extremity 
join  the  splenic  lymphatics. 

The  lymphatic  vessels  of  the  small  intestine  are  usually  called  the 
lac'teals,4  from  the  fact  of  their  conveying  the  chyle,  which  gives  them 
the  appearance  of  being  filled  with  milk.  From  the  intestine  they  pro- 
ceed between  the  layers  of  the  mesentery,  traversing  in  their  course  one 
hundred  and  thirty  or  more  mesenteric  glands.5  These  are  irregularly 
arranged  in  three  rows,  of  which  the  first  contains  the  smallest  glands 
but  the  greatest  number,  and  the  last  the  fewest  and  largest.  Their 
efferent  vessels  terminate  in  the  cceliac  glands. 

The  lymphatic  vessels  of  the  large  intestine  traverse  about  thirty 
mesocol'ic  glands,6  and  terminate  for  the  most  part  in  the  superior  me- 
senteric glands ;  those  from  the  greater  portion  of  the  descending  colon 
terminating  in  the  left  lumbar  glands. 

The  lymphatic  vessels  of  the  spleen  and  pancreas  follow  the  direction 
of  the  splenic  vein,  traversing  in  their  course  a  number  of  small  glands,7 
and  terminate  in  the  cceliac  glands. 

The  lymphatic  vessels  of  the  upper  surface  of  the  liver,  as  before 
mentioned,  for  the  most  part  ascend  through  the  suspensory  ligament  to 

1  G.  lumbares  ;  plexus  lumbaris.  4  Vasalactea;  v.  chylifera;  chyliferous 

'2  Truncus  lymphaticus  lumbaris.  vessels. 

3  G.  gastro-epiploicae    superiores   and  6  G.  mesenteries  or  meseraicae 

inferiores.  6  G.  mesocolicse. 

7  G.  splenico-pancreaticao. 


THE  VASCULAR  SYSTEM.  439 

join  the  anterior  mediastinal  glands.  Those  of  the  lower  surface  and 
the  deep  vessels  emerging  from  the  transverse  fissure  of  the  liver,  after 
traversing  a  few  small  glands,1  associate  with  the  lymphatics  of  the  lesser 
curvature  of  the  stomach,  and  terminate  in  the  mesenteric  glands. 

The  cce'liac  glands,2  from  fifteen  to  twenty  in  number,  are  situated 
behind  the  duodenum  and  pancreas,  upon  the  aorta,  the  coeliac  and 
superior  mesenteric  arteries,  and  the  portal  vein,  and  are  intimately  asso- 
ciated with  the  lumbar  glands  on  each  side.  Their  efferent  vessels  con- 
join to  form  the  intestinal  lymphatic  trunk,3  frequently  represented  by 
two  or  more  smaller  ones,  terminating  in  the  receptacle  of  the  chyle. 


1  G.  hepaticse.  2  G.  coeliacse;  plexus  coeliacus. 

3  Truncus  lymphaticus  intestinalis,  or  abdominalis. 


CHAPTER  VIII. 

THE    VOCAL    AND    RESPIRATORY    APPARATUS. 

THE  LARYNX. 

THE  Lar'ynx,1  the  organ  of  the  voice,  is  situated  at  the  top  of  the 
trachea,  below  the  root  of  the  tongue  and  the  hyoid  bone.  At  the 
period  of  puberty  it  becomes  much  larger  in  the  male  than  the  female, 
and  in  the  former  produces  the  conspicuous  prominence  in  the  middle  of 
the  neck,  commonly  known  as  " Adam's  apple."2  It  is  bounded  behind 
by  the  pharynx,  with  which  it  communicates  above,  and  it  opens  below 
into  the  trachea. 

In  composition  the  larynx  consists  of  a  frame-work  of  cartilages  con- 
nected by  ligaments,  provided  with  appropriate  muscles,  blood-vessels, 
and  nerves,  and  lined  with  mucous  membrane. 

CARTILAGES  OF  THE  LARYNX. 

The  Cartilages  of  the  larynx  consist  of  three  symmetrical  pieces, 
named  the  thyroid,  cricoid,  and  epiglottic  cartilages,  and  a  pair  called 
the  arytenoid  cartilages. 

The  Thy'roid  cartilage,3  the  largest  of  those  of  the  larynx,  is  situated 
at  the  upper  fore  part  of  the  latter,  and  consists  of  two  lateral  wing-like 
plates  conjoined  in  front  and  diverging  behind.  In  the  male,  after  pu- 
berty, the  line  of  union  of  the  two  plates  forms  an  acute  prominence 
above,  and  gradually  recedes  and  becomes  more  obtuse  below.  In  the 
female  and  young  male  it  is  less  prominent  above,  and  more  uniformly 
rounded  or  obtuse. 

Each  half  of  the  thyroid  cartilage  is  a  quadrilateral  plate,  with  the 
inner  and  outer  surfaces  sloping,  and  the  borders  rounded.  The  outer 
surface  presents  an  oblique  ridge  for  the  attachment  of  muscles.  The 

1  Pars  prima  asperse  arteriae  ;  caput,  2  Nodus  gutturis ;  promenentia  laryn- 

operculum,    initium,    finis    superior,   or       gls- 

terminus  superior  asperse  arterise.  3  Adami  morsus  os  ;  scutum ;  cartila- 

go-scutiformis ;  c.  clypealis ;  c.  peltalis. 

(440) 


THE   VOCAL   AND   RESPIRATORY   APPARATUS. 


441 


FIG.  281. 


posterior  angles  are  prolonged  into  blunt  processes,  named  the  horns,1  of 
which  the  superior  are  the  longer.  The  borders  are  sigmoid  in  their 
course;  the  upper  one  being  so  to  the  greatest  degree,  and  meeting  that 
of  the  opposite  side  in  a  deep  notch  in  front  of  the  thyroid  cartilage. 

The  Cri'coid  cartilage,2  situated  below  the  former,  and  connected 
with  the  first  ring  of  the  trachea,  in  shape  resembles  a  seal-ring.  It  is 
narrow  in  front,  and  gradually  deepens  poste- 
riorly. Its  lower  border,  somewhat  waving  in 
its  course,  is  horizontal.  The  upper  border 
ascends  from  the  front,  and  at  the  back  part  is 
provided  with  a  pair  of  convex,  oval  promi- 
nences, which  articulate  with  the  arytenoid  car- 
tilages. 

On  each  side  externally  of  the  cricoid  carti- 
lage there  is  a  slightly  prominent  circular  facet 
for  articulation  with  the  inferior  horns  of  the 
thyroid  cartilage.  The  posterior  surface  is 
divided  by  a  slight  vertical  ridge  giving  attach- 
ment to  the  oesophagus;  and  on  each  side  of 
this  ridge  is  a  broad,  shallow  depression,  accom- 
modating the  posterior  crico-arytenoid  muscle. 


CARTILAGES  OF  THE  LARYNX,  front 
view.    1,  thyroid  cartilage;  2,  its 


The  Epiglottis3  is  a  somewhat  spoon-shaped 
plate  of  fibro-cartilage  invested  with  mucous 
membrane,  projecting  above  the  aperture  of  the 
larynx,  which  is  closed  against  it  in  the  act  of 
swallowing.  In  the  ordinary  condition  of  rest  the  cricoid  cartilage  ;e,  its  anterior 
it  occupies  an  oblique  position  behind  the  body  ^^^!  7' the  tw°  aryte" 
of  the  hyoid  bone,  with  its  free  extremity  bent 

toward  the  root  of  the  tongue.  Its  outline  is  ovoid,  with  the  broader 
extremity  free,  and  the  narrower  extremity  prolonged  and  attached  by  a 
band  of  fibro-elastic  tissue  to  the  thyroid  cartilage  within  the  entering 
angle  of  its  two  halves.  The  free  borders  of  the  epiglottis  are  thin  and 
slightly  everted.  The  surface  directed  forward  or  toward  the  mouth  is 
convex,  and  that  toward  the  aperture  of  the  larynx  is  concave. 

The  Aryt'enoid.  cartilages,4  smaller  than  the  others,  are  situated  on 


1  Cornua ;  cornu  longum,  or  superius 
and  c.  breve,  or  inferius ;  greater  and 
lesser  cornu. 

2  Cartilage  cricoideus  ;    c.  annularis  ; 
c.  cymbalaris;  c.  innominata. 


3  Epiglottic  cartilage ;  operculum  la- 
ryngis ;    lingua    exigua ;     sublinguum ; 
lingula  fistulse  ;  lingula ;  superligula. 

4  Cartilagines  arytenoides;    c.  guttu- 
rales;  c.  triquetrse;  c.  pyramidales;  gut- 
turnia. 


442       THE  VOCAL  AND  RESPIRATORY  APPARATUS. 

the  summit  of  the  cricoid  cartilage  posteriorly.  They  are  three  sided, 
pyramidal,  and  curved.  Their  base  is  concave,  and  articulates  with  a 
corresponding  prominence  of  the  cricoid  cartilage.  Their  apex  is  bent 
backward,  and  is  surmounted  with  a  nodule  of  cartilage1  attached  by 
means  of  a  ligament.  The  posterior  surface  is  concave,  and  accommo- 
dates the  arytenoid  muscles ;  the  anterior  surface  is  convex,  and  has 
attached  the  thyro-arytenoid  muscle  ;  and  the  inner  surface  is  opposed  to 
that  of  the  opposite  cartilage,  leaving  an  intervening  notch  lined  with 
mucous  membrane. 

Of  the  three  angles  of  the  base  of  the  arytenoid  cartilages,  the  outer 
one2  gives  attachment  to  the  crico-arytenoid  muscles,  and  the  anterior3 
is  prolonged  and  gives  attachment  to  the  vocal  membrane. 

A  small  piece  of  cartilage4  frequently  exists  extending  from  the  aryt- 
enoid cartilages  upward  into  the  aryteno-epiglottic  folds. 

The  cartilages  of  the  larynx,  as  they  are  commonly  named,  are  com- 
posed of  true  cartilage,  except  the  epiglottis,  which  is  fibro-cartilaginous. 
They  are  all  invested  with  a  perichondrium,  and  with  the  advance  of 
life  the  true  cartilages  are  strongly  disposed  to  ossify.  When  the  epi- 
glottis is  stripped  of  its  membranous  investment,  it  is  seen  to  present  a 
corroded  aspect  arising  from  the  existence  of  numerous  irregular  pits  for 
the  accommodation  of  small  racemose  glands. 

ARTICULATIONS  AND  LIGAMENTS  OF  THE  LARYNX. 

The  Thyro-hyoid  membrane5  is  a  rather  loose  fibre-elastic  structure 
connecting  the  upper  border  of  the  thyroid  cartilage  with  the  inner  sur- 
face of  the  hyoid  bone.  It  is  thickest  and  most  dense  in  front,  and  is 
thin  at  the  sides. 

The  Thyro-hyoid  ligaments6  are  cylindrical,  fibro-elastic  cords,  join- 
ing the  superior  horns  of  the  thyroid  cartilage  with  the  ends  of  the  great 
horns  of  the  hyoid  bone.  At  their  middle  they  usually  contain  -an  im- 
bedded nodule  of  cartilage,7  which  is  sometimes  ossified. 

The  Crico-thyroid  articulation  is  formed  on  each  side  of  the  larynx, 
between  the  inferior  horn  of  the  thyroid  cartilage  and  the  side  of  the 
cricoid  cartilage.  It  is  lined  with  a  synovial  membrane,  and  surrounded 

1  Corniculum  laryngis;  tuberculated,  4  Cuneiform    cartilage;     cartilage   of 
or  supra-arytenoid  cartilage ;  cartilage       Wrisberg. 

of  Santorini ;  capitulum  Santorini.  5  Middle  thyro-hyoid  ligament. 

2  Processus  muscularis.  6  Lateral  thyro-hyoid  ligaments. 

3  Processus  vocalis.  7  Cartilage  tritlcea. 


THE   VOCAL   AND  RESPIRATORY  APPARATUS. 


443 


FIG.  282. 


by  a  capsular  ligament.     This  joint  permits  a  movement  of  the  thyroid 
cartilage  downward  and  forward,  and  in  the  reverse  direction. 

The  Crico-aryt'enoid  articulation  is  a  ball-and-socket  joint,  formed 
on  each  side  of  the  larynx  between  the  hollow  base  of  the  arytenoid  car- 
tilage and  a  corresponding  convexity  of  the  cricoid  cartilage.  It  is 
lined  with  synovial  membrane,  and  surrounded  by  a  capsular  ligament. 
The  joint  allows  movement  of  the  arytenoid  cartilage  in  all  directions. 

The  Thyro-epiglottic  ligament1  is  a  fibro-elastic  band  attaching  the 
narrow  extremity  of  the  epiglottis  to  the  upper  part  of  the  entering 
angle  of  the  thyroid  cartilage. 

The  Vocal  membrane,2  composed  of  elastic  tissue,  springs  from  the 
front  and  sides  of  the  upper  border  of  the  cricoid  cartilage,  and  extends 
upward  to  the  bases  of  the  aryte- 
noid cartil-ages  and  the  lower  part 
of  the  entering  angle  of  the  thy- 
roid cartilage.  Its  inferior-portion 
is  strongest,  and  is  visible  in  the 
interval  of  the  cricoid  and  thyroid 
cartilages  at  the  front  of  the  larynx. 
Its  lateral  portions  are  thin,  and 
are  separated  from  the  sides  of  the 
thyroid  cartilage  by  the  interven- 
ing thyro -arytenoid  muscles.  Its 
upper  margins,  somewhat  thickened, 
extend  between  the  entering  angle 
of  the  thyroid  cartilage  and  the 
anterior  prominent  angle  of  the 
base  of  the  arytenoid  cartilages. 
These  margins  correspond  in  po- 
sition with  the  lower  edge  of  the 
ventricles  of  the  larynx,  and  are  almost  universally  described  as  the 
"vocal  cords,"3  which,  as  peculiar  or  separate  organs,  do  not  exist. 

MUSCLES   OF  THE  LARYNX. 

The  muscles  of  the  larynx,  except  the  arytenoid  muscle,  are  in  pairs, 
situated  on  each  side  of  the  larynx. 

1  Lig.  thyro-epiglotticum.  3  Chordae  vocales;  c.  v.  verse:  c.  Fer- 

2  Membrana  vocalis;    phonetic  mem-  reinii ;    superior   thyro-arytenoid   liga- 
brane;  crico-thyroid  membrane,  or  liga-  ments;  inferior  ligaments  of  the  larynx ; 
ment ;  conoid,  or  pyramidal  ligament.  lips  of  the  glottis. 


VIEW  OF  THE  VOCAL  MEMBRANE.  1,  left  half  of  the 
thyroid  cartilage ;  2,  right  half  turned  forward  aiid 
partly  cut  away;  3,  cricoid  cartilage;  4,  arytenoid 
cartilages;  5,  right  half  of  the  vocal  membrane;  6, 
upper  border  of  the  left  half;  7,  arytenoid  muscle. 
The  upper  borders  of  the  vocal  membrane,  extended 
between  the  arytenoid  cartilages  and  the  thyroid, 
constitute  the  so-called  "  true  vocal  cords." 


444 


THE   VOCAL   AND  RESPIRATORY  APPARATUS. 


The  Crico-thyroid  muscle1  arises  from  the  front  and  side  of  the  cri- 
coid  cartilage,  and  ascends  outward  and  backward  to  be  inserted  into 
the  lower  border  of  the  thyroid  cartilage.  It  draws  the  latter  down- 
ward and  forward,  the  centre  of  motion  being  the  articulation  between 
the  inferior  horn  of  the  thyroid  and  the  side  of  the  cricoid  cartilage. 
The  result  of  the  movement  is  to  render  the  vocal  membrane  tense. 


FIG.  283. 


The  Posterior  Crico-aryt'enoid  muscle2  arises  from  the  broad  depres- 
sion at  the  side,  posteri- 
orly of  the  cricoid  carti- 
lage, and  converges  up- 

^  \  ward  and  outward  to  be 

.inserted  into  the  external 
angle  of  the  base  of  the 
arytenoid  cartilage.  It 
rotates  the  latter  on  its 
base  outward  and  back- 
ward, rendering  the  vocal 
membrane  tense,  and 
widening  the  glottis. 

The  Lateral  Crico- 
aryt'enoid  muscle,3 
smaller  than  the  preced- 
ing, is  situated  under 
cover  of  the  side  of  the 
thyroid  cartilage.  It 
arises  from  the  upper 
border,  laterally  of  the 

two  laminae  of  the  aryteno-epiglottic  fold  separated  so  as  to  ex-     cricoid      Cartilage,     and 

passes  upward  and  back- 
ward to  be  inserted  into 
the  external  angle  of  the 
base  of  the  arytenoid  car- 
tilage. It  rotates  the  latter  on  its  base  outward  and  forward,  relaxing 
the  vocal  membrane  and  widening  the  glottis. 

The  Thyro-aryt'enoid  muscle,4  situated  immediately  above  the  pre- 


MUSCLES  OF  THE  LARYNX.  1,  right  half  of  the  thyroid  cartilage, 
turned  forward;  2,  superior  horns;  3,  inferior  horn  marked  by 
the  crico-thyroid  articulation ;  4,  the  other  portion  of  the  latter 
on  the  side  of  the  cricoid  cartilage ;  5,  arytenoid  cartilages,  sur- 
mounted by  nodules  of  the  same  substance;  6,  epiglottis;  7,  the 


pose  the  muscles ;  8,  lower  part  of  the  vocal  membrane ;  9,  crico- 
thyroid  muscle ;  10,  posterior  cricq-ary tenoid  muscle ;  11,  lateral 
crico-arytenoid ;  12,  thyro-arytenoid ;  13,*thyro-epiglottic  muscu- 
lar fibres ;  14,  aryteno-epiglottic  muscular  fibres ;  15,  arytenoid 
muscle. 


1  M.  crico-thyroideus;  anterior  dilator 
of  the  larynx. 

2  M.  crico-arytsenoideusposticus;  pos- 
terior dilator  of  the  larynx, 


3  M.  crico-arytomoideus  lateralis. 
*  M.  thyro-arytenoidceus. 


THE   VOCAL   AND  RESPIRATORY   APPARATUS.  445 

ceding,  arises  from  the  inner  surface  of  the  thyroid  cartilage  at  its  enter- 
ing angle,  and  from  the  contiguous  portion  of  the  vocal  membrane,  and 
passes  backward  to  be  inserted  into  the  outer  surface  and  base  of  the 
arytenoid  cartilage.  It  draws  the  latter  forward,  and  relaxes  the  vocal 
membrane. 

The  Aryt/enoid  muscle1  consists  of  several  transverse  and  obliquely 
crossing  fasciculi,  passing  between  the  posterior  concave  faces  of  the 
arytenoid  cartilages.  It  draws  the  latter  together,  and  thus  narrows 
the  glottis. 

Besides  the  preceding  well-characterized  muscles,  there  exist  some  thin 
fleshy  fasciculi  which  are  not  constant  in  extent  or  arrangement.  Some 
of  these  diverge  from  the  entering  angle  of  the  thyroid  cartilage  to  the 
sides  of  the  epiglottis,2  while  others  pass  from  the  latter  to  the  sides  of 
the  arytenoid  cartilages.3 

THE  CAYITY  OF  THE  LARYNX. 

The  lining  mucous  membrane  of  the  larynx  is  continuous  with  that  of 
the  pharynx  and  trachea.  Extending  from  the  root  of  the  tongue  to  the 
epiglottis,  it  forms  the  three  glosso-epiglot'tic  folds.4  Reflected  from 
the  sides  of  the  epiglottis  to  the  summits  of  the  arytenoid  cartilages,  it 
forms  the  aryt'eno-epiglot'tic  folds.5  Dipping  into  a  notch  between  the 
summits  of  the  arytenoid  cartilages,  it  extends  from  the  front  of  these 
into  the  cavity  of  the  larynx,  and  behind  them  into  the  pharynx  toward 
the  commencement  of  the  oesophagus. 

The  aperture  of  the  larynx,6  communicating  with  the  pharynx,  is  tri- 
angular and  oblique.  Its  base  or  wider  portion  above  is  formed  by  the 
epiglottis,  its  sides  by  the  aryteno-epiglottic  folds,  and  its  apex  or  nar- 
row extremity  by  the  notch  separating  the  summits  of  the  arytenoid 
cartilages. 

Descending  from  the  aperture  into  the  cavity  of  the  larynx,  the  mu- 
cous membrane  is  reflected  at  each  side,  outward  and  upward,  forming  a 
pair  of  pouches  named  the  ventricles  of  the  larynx.7  These  are  half 

1  M.  arytaenoideus  ;    m.    arytaenoidei  5  Ligamenta  epiglottideo-arytoenoidea. 
transversi  and  obliqui.  6  Superior   aperture    of    the   larynx  ; 

2  M.  thyro-epiglottideus.  aditus  laryngis. 

3  M.  aryteno-epiglottideus  ;    compres-  »  Ventriculi  laryngis ;    sacculi  laryn- 
sor  sacculi  laryngis;    m.  ary-epiglotti-  gis ;  sinuses  of  the  larynx;   laryngeal 
dseus  pouches;    ventriculi  Morgagni,  or  Ga- 

4  Glosso-epiglottic  freena ;    ligamenta  leni. 
glosso-epiglottica. 


44(5 


THE   VOCAL   AND   RESPIRATORY   APPARATUS. 


oval  recesses  communicating  with  the  cavity  of  the  larynx  by  a  trans- 
verse elliptical  orifice.     The  lower  edge  of  the  latter  corresponds  with 

FIG.  284 


VERTICAL  SECTION  or  THE  FACE  AND  NECK,  THROUGH  THE  MEDIAN  LINE  ANTERO-POSTERIORLY,  EXPOSING  TO 
VIEW  THE  NOSE,  MOUTH,  PHARYNX,  AND  LARYNX.  1,  oval  cartilage  of  the  left  nostril;  2,  triangular  cartilage; 
3,  line  of  separation  between  the  two;  4,  prolongation  of  the  oval  cartilage  along  the  column  of  the  nose; 
5,  superior  meatus  of  the  nose;  6,  middle  meatus;  7,  inferior  meatus;  8,  sphenoidal  sinus;  9,  posterior 
part  of  the  left  nasal  cavity,  communicating  with  the  pharynx;  10,  orifice  of  the  Eustachian  tube;  11, 
upper  extremity  of  the  pharynx;  12,  soft  palate,  ending  below  in  the  uvula;  13,  interval  of  the  mouth 
between  the  lips  and  jaws;  14,  roof  of.  the  mouth,  or  hard  palate;  15,  communication  of  the  cavity  of  the 
mouth  with  the  interval  between  the  jaws  and  cheek ;  16,  tongue ;  17,  fibrous  partition  in  the  median  line 
of  the  latter;  18,  genio-glossal  muscle;  19,  genio-hyoid  muscle;  20,  mylo-hyoid  muscle;  21,  anterior  half 
arch  of  the  palate;  22,  posterior  half  arch  of  the  palate;  23,  tonsil;  24,  25,  floor  of  the  fauces;  26,  27, 
pharynx;  28,  cavity  of  the  larynx;  29,  ventricle  of  the  larynx;  30,  epiglottis;  31,  hyoid  bone;  32,  33, 
thyroid  cartilage;  34,  thyro-hyoid  membrane;  35,  36,  cricoid  cartilage;  37,  vocal  membrane. 

the  upper  border  of  the  vocal  membrane,  or  with  what  are  commonly 
termed,  on  the  two  sides  together  of  the  larynx,  the  vocal  cords.1  The 
upper  edge  of  the  orifice  of  the  ventricles  is  rendered  slightly  prominent 


1  Chordae  vocales;  c.  v  verae;  ligamenta  glottidis  verae;  1.  thyro-arytenoideoe  in- 
feriora ;  inferior,  or  true  vocal  cords ;  lips  of  the  glottis  ;   chordae  Ferreinii. 


THE   VOCAL   AND   RESPIRATORY   APPARATUS  447 

by  an  accumulation  of  the  subjacent  connective  tissue,  usually  called,  on 
the  two  sides  of  the  larynx,  the  false  vocal  cords.1 

From  the  ventricles  of  the  larynx,  the  mucous  membrane  extends 
downward,  lining  the  vocal  membrane  and  the  cricoid  cartilage,  and  be- 
coming continuous  with  that  of  the  trachea. 

The  cavity  of  the  larynx  gradually  narrows  from  its  aperture  down- 
ward to  the  space  between  the  inferior  edges  of  the  orifices  of  the  laryn- 
geal  ventricles.  The  narrowest  portion  of  this  space,  named  the  glottis,2 
forms  an  isosceles  triangle,  of  which  the  apex  is  at  the  entering  angle 
of  the  thyroid  cartilage ;  the  sides  correspond  with  the  edges  of  the 
vocal  membrane,  and  the  base  is  in  relation  with  the  arytenoid  cartilages. 
Below  the  glottis  the  cavity  of  the  larynx  gradually  widens  and  assumes 
the  circular  form  of  the  interior  of  the  cricoid  cartilage. 

The  mucous  membrane  of  the  larynx  is  soft,  thin,  and  pale  red.  It 
adheres  tightly  to  the  epiglottis,  the  vocal  membrane,  and  the  interior  of 
the  cricoid  cartilage,  but  in  other  positions  is  more  loosely  attached  to 
the  parts  beneath  by  an  abundant  connective  tissue.  It  is  provided  with 
numerous  small  racemose  glands,  and  its  epithelium  is  of  the  ciliated 
columnar  form. 

Between  the  lower  part  of  the  epiglottis  and  the  root  of  the  tongue 
there  is  an  abundant  deposit  of  connective,  elastic,  and  adipose  tissue, 
and  a  similar  deposit,  with  many  racemose  glands,  is  situated  beneath 
the  mucous  membrane  in  front  of  the  arytenoid  cartilages. 

The  arteries  of  the  larynx  are  derived  from  the  superior  and  inferior 
thyroid.  The  veins  are  branches  of  the  thyroid  veins.  The  lymphatics 
enter  the  cervical  glands.  The  nerves  are  derived  from  the  laryngeal 
branches  of  the  pneumogastric  and  the  sympathetic  nerves. 

THE  ORGANS  OF  RESPIRATION. 

The  respiratory  apparatus  consists  of  the  trachea  and  lungs,  together 
with  the  thorax  and  appropriate  muscles.  The  latter  have  already  been 
described,  and  it  now  remains  to  examine  the  former. 

THE  TRACHEA. 

The  Tra'chea  or  Windpipe,3  the  main  air-passage  of  the  lungs,  is  a 
cylindrical  tube  descending  the  neck  in  front  of  the  oesophagus  into  the 

Chordae  vocales  spurioe ;    ligamenta  3  Aspera  arteria;    fistula  pulmonalis, 

glottidis  spuriae;  1.  thyro-arytenoidese  or  spiritualis  ;  canna;  syrinx;  weasand; 
superiora ;  superior,  or  false  vocal  cords.  throttle ;  bronchus. 

2  Glottis  vera ;  rima  glottidis ;  fissure 
of  the  glottis  ;  true  glottis ;  ligula. 


448 


THE  VOCAL  AND  KESPIRATORY  APPARATUS. 


thorax.  Commencing  at  the  larynx  opposite  the  fifth  cervical  vertebra, 
it  terminates  by  dividing  into  the  two  bronchi  opposite  the  third  dorsal 
vertebra.  Its  length  is  about  four  inches ;  its  breadth,  less  in  the  female 
than  the  male,  is  from  three-fourths  to  one  inch.  In  the  neck  it  is 
bounded  on  each  side  by  the  great  blood-vessels ;  and  in  the  thorax  is 
just  behind  the  upper  part  of  the  sternum. 

FIG.  285. 


A. — FRONT  OF  THE  LARYNX,  TRACHEA,  AND  BRONCHI.  1,  hyoid  bone ;  2,  thyro-hyoid  membrane ;  3,  thy- 
roid cartilage;  4,  lower  part  of  the  vocal  membrane;  5,  cricoid  cartilage;  6,  trachea  ;  7,  8,  two  cartilag- 
inous rings ;  9,  intervening  fibro-elastic  membrane  connecting  the  rings ;  10,  11.  right  and  left  bronchi 
dividing  into  the  bronchial  tubes. 

B. BACK  OF  THE  LARYNX,  TRACHEA,  AND  BRONCHI.  1,  aperture  of  the  larynx ;  2,  3,  spaces  between  the 

sides  of  the  thyroid  cartilage,  and  the  cricoid  and  arytenoid  lined  with  mucous  membrane  extending 
downward  to  the  oesophagus ;  4,  membranous  space  at  the  back  of  the  trachea ;  5,  muscular  fibres  passing 
across  the  space  and  exposed  by  removing  a  fibrous  layer  containing  the  tracheal  glands ;  6,  outer  surface 
of  the  mucous  membrane  within  the  muscular  layer;  7,  8,  ends  of  the  cartilaginous  rings. 

The  Bron'chi1  diverge  from  the  trachea  to  the  lungs,  behind  the  great 
blood-vessels  emanating  from  the  base  of  the  heart.  The  right  bron/- 
chus,2  about  an  inch  in  length,  passes  nearly  at  a  right  angle  to  the  root 
of  the  corresponding  lung,  on  a  level  with  the  fourth  dorsal  vertebra, 


Bronchia ;  bronchiae ;  cannulae  pulmonum. 


2  Bronchus  dexter. 


THE   VOCAL  AND  RESPIRATORY  APPARATUS.  449 

and  behind  the  right  pulmonary  artery.  The  left  bron'chus,1  narrower 
than  the  right,  but  about  twice  its  length,  passes  downward  and  out- 
ward beneath  the  arch  of  the  aorta  to  the  root  of  the  corresponding 
lung,  on  a  level  with  the  fifth  dorsal  vertebra  and  behind  the  left  pulmo- 
nary artery. 

The  trachea  and  bronchi  are  composed  of  a  series  of  cartilaginous 
rings  connected  by  a  fibro-elastic  membrane,  and  lined  with  mucous 
membrane.- 

The  cartilaginous  rings2  encircle  the  trachea  and  bronchi,  but  are  im- 
perfect at  their  posterior  third.  They  are  flat  on  their  outer  surface  and 
convex  on  their  inner  surface,  and  therefore  appear  more  prominent  in 
the  latter  position.  A  strong  fibro-elastic  membrane  connects  their  ad- 
jacent edges,  and  in  a  thinned  condition  extends  over  them.  The  poste- 
rior interval  of  the  cartilaginous  rings  is  occupied  by  a  loose  fibrous 
membrane  and  an  internal  layer  of  pale,  unstriated  muscular  fibres 
having  a  transverse  direction. 

The  last  of  the  cartilaginous  rings  of  the  trachea  is  modified  in  form 
so  as  to  accommodate  itself  to  the  two  first  rings  of  the  bronchi;  its 
lower  margin  being  prolonged  in  front  to  a  median  point,  which  is  bent 
backward. 

The  mucous  membrane  of  the  trachea  and  bronchi  is  pinkish  white, 
and  smooth,  except  that  there  are  some  fine  longitudinal  ridges  at  their 
posterior  or  membranous  part,  produced  by  reticular  bundles  of  sub- 
mucous  elastic  tissue,  which  conspicuously  occupy  this  position.  The 
epithelium  is  of  the  ciliated  columnar  form ;  the  vibrating  movement  of 
the  cilia  during  life  being  directed  upward. 

The  trachea  and  bronchi  are  provided  with  numerous  minute  racemose 
glands3  which  open  upon  the  surface  of  the  mucous  membrane.  The 
largest  of  these  are  imbedded  in  the  posterior  fibrous  membrane ;  and 
their  terminal  orifices  are  distinctly  visible  as  numerous  fine  punctures  on 
the  free  surface  of  the  contiguous  mucous  membrane.  Smaller  glands 
occupy  the  intervals  of  the  rings,  and  likewise  distinctly  exhibit  their 
terminal  orifices  on  the  adjacent  mucous  membrane. 

The  trachea  and  bronchi  are  supplied  by  the  inferior  thyroid  and 
bronchial  arteries ;  their  veins  terminate  in  the  thyroid  and  bronchial 
veins ;  and  their  nerves  are  derived  from  the  pneumogastric  and  sympa- 
thetic nerves. 

1  Bronchus  sinister.  s  Tracheal  and  bronchial  glands  ;  glan- 

2  Annuli  cartilaginei ;  segmenta  card-      dulse    muciparae    tracheales    et    bron- 
laginea ;  orbes  cartilaginosi.  chiales. 

29 


450  THE  VOCAL  AND  RESPIRATORY  APPARATUS. 


THE  LUNGS. 

The  Lungs1  occupy  the  cavity  of  the  thorax  on  each  side,  separated  by 
the  heart  and  great  blood-vessels.  They  accurately  fill  the  spaces  which 
contain  them  in  the  constantly  changing  capacity  of  the  chest  during  res- 
piration. They  are  free  or  unattached  everywhere  except  at  their  root, 
and  are  closely  invested  with  a  serous  membrane,  the  pleura. 

FIG.  286. 


THE  TRACHEA,  LUNGS,  AND  HEART.  1,  larynx ;  2,  crico-thyroid  muscle;  3,  trachea;  4,  5,  6,  upper,  middle, 
and  lower  lotes  of  the  right  lung ;  7,  8,  upper  and  lower  lobes  of  the  left  lung ;  the  anterior  part  of  both 
lungs  is  drawn  aside  by  hooks  so  as  to  expose  to  view  9,  the  heart  contained  within  its  pericardium;  10, 
anterior  mediastinal  space,  the  line  on  each  side  indicating  the  position  at  which  the  pleuraa  are  reflected 
from  the  pericardium  to  the  front  wall  of  the  thorax;  11,  left  subclavian  artery;  12,  left  common  carotid  ; 
13,  right  common  carotid;  14,  right  subclavian;  15,  left  innominate  vein;  16,  right  innominate  vein ;  17, 
18,  left  subclavian  and  internal  jugular  veins;  19,20,  right  internal  jugular  and  subclavian  veins;  21,  root 
of  the  lung. 

The  root2  of  each  lung  is  situated  near  its  middle  internally,  and 
consists  of  the  corresponding  bronchus,  pulmonary  artery  and  veins, 
the  bronchial  blood-vessels,  nerves,  and  lymphatics,  surrounded  by  a 

ipulmones;  pulmo  dexter  and  sinister ;  pneumones;  pjeumones;  lights;  spira- 
menta  animae  ;   flabella  et  ventilabra  cordis ;  ergasteriones  spiritu. 
2  Radix,  or  pedunculus  pulmonis. 


THE   VOCAL  AND  RESPIRATORY   APPARATUS.  451 

reflection  of  the  pleura.  The  root  of  the  right  lung  is  behind  the  su- 
perior cava,  and  has  the  azygos  vein  arching  over  it  as  this  communi- 
cates with  the  former  vessel.  The  root  of  the  left  lung  lies  partly 
beneath  the  arch  and  partly  in  front  of  the  descending  portion  of  the 
aorta. 

In  the  root  of  the  right  lung  the  bronchus  is  highest,  the  pulmonary 
artery  is  next,  and  the  pulmonary  veins  are  lowest.  In  the  root  of  the 
left  lung  the  pulmonary  artery  is  highest,  and  then  follows  the  bronchus, 
succeeded  by  the  veins. 

Before  entering  a  depression  at  the  root  of  the  lungs,  named  the  hilus,1 
the  bronchi  subdivide :  the  right  into  three  branches,  the  left  into  two, 
in  correspondence  with  the  number  of  lobes  of  each  lung.      The  pulmo 
nary  blood-vessels  also  commence  subdivision  before  entering  the  lungs. 

Each  lung  is  conical,  with  a  broad,  concave  base  resting  on  the  dia- 
phragm ;  a  rounded  apex  extending  above  the  level  of  the  first  rib  into 
the  neck;  an  outer  convex  surface  ;  and  an  inner  concave  surface  directed 
toward  the  heart.  The  posterior  border  is  long,  thick,  and  convex,  and 
occupies  the  side  of  the  vertebral  column ;  the  anterior  border  is  thin 
and  sharp,  and  folds  around  the  heart  included  within  its  pericardium. 
The  margin  of  the  base  is  acute,  and  outwardly  occupies  the  narrow 
angular  interval  between  the  origin  of  the  diaphragm  and  the  inferior 
border  of  the  thorax. 

The  lungs  vary  in  weight  and  capacity  according  to  many  conditions, 
such  as  age,  sex,  size  of  the  individual,  state  of  health,  and  habit  of  ex- 
ercise. In  the  adult  their  approximate  weight  is  about  two  and  a  half 
pounds,  and  their  total  capacity  about  three  hundred  cubic  inches.  Their 
long  diameter  is  the  greatest,  and  is  deepest  posteriorly.  The  right 
lung  is  shorter  than  the  left,  but  wider,  and  of  somewhat  greater  bulk. 

Each  lung  is  divided  by  a  fissure,  commencing  a  short  distance  below 
the  apex  posteriorly  and  descending  obliquely  forward  to  the  base  ante- 
riorly. The  right  lung  is  further  divided  by  a  fissure  proceeding  from 
the  first  obliquely  forward  to  its  anterior  margin.  Thus  the  right  lung 
has  three  lobes,2  of  which  the  middle  one  is  the  smallest  and  the  lowest 
one  is  the  largest ;  the  left  lung  has  two  lobes,2  of  which  the  lower  is 
the  larger.  Between  the  lobes  of  the  left  lung  in  front  there  exists  a 
large  angular  notch,  corresponding  with  the  position  at  which  the  im- 
pulse of  the  heart  is  felt  against  the  walls  of  the  chest  during  life. 

In  infancy  the  lungs  are  of  a  pale-rose  color;  but  as  life  advances 
they  assume  a  pinkish-gray  or  more  or  less  leaden  hue,  variegated  with 
spots  and  streaks  of  a  dark-slate  or  bluish-black  color.  This  change  is 

1  Porta  pulmonis.  2  Lobi,  or  aloe  pulmonum. 


452 


THE  VOCAL  AND  RESPIRATORY  APPARATUS. 


due  to  the  gradual  deposition  in  the  structure  of  the  lungs  of  minute 
granules  of  a  black  pigmentary  matter.  The  surface  of  the  lungs  is 
smooth  and  shining,  and  distinctly  marked  with  polyhedral  outlines, 
indicating  a  lobular  constitution  in  these  organs. 

The  lungs  are  highly  elastic,  so  that  if  the  cavities  containing  them 
are  opened,  they  collapse  to  about  one-third  of  their  previous  bulk ;  and 
they  may  again  be  readily  inflated  by  artificial  means.  Their  substance 
is  of  a  sponge-like  consistence,  readily  floats  in  water,  and  imparts  a 
crackling  sensation  when  compressed  between  the  fingers.  In  the  foetus 
before  birth,  or  before  respiration  has  taken  place,  they  are  heavier  than 
water  and  sink  in  that  fluid.  A  similar  condition  is  observed  in  certain 
diseases,  in  which  from  congestion  or  effusion  the  lungs  become  more  or 
less  consolidated.  On  cutting  a  healthy  lung  and  compressing  it,  a  red- 
dish, frothy  liquid  exudes,  consisting  of  mucus  mingled  with  blood  and 
air  bubbles. 

The  lungs  are  composed  of  numerous  small,  polyhedral  primary  lob- 
ules,1 which  unite  into  larger  secondary  lob- 
ules of  the  same  general  form.  The  latter  give 
rise  to  the  polyhedral  markings  on  the  surface 
of  the  lungs,  and  close  inspection  will  lead  to 
the  discovery  of  the  outlines  of  the  primary 
lobules  composing  them.  Both  the  primary 
and  secondary  lobules  are  associated  by  means 
of  connective  tissue  ;2  they  are  most  distinctly 
observed  in  the  young,  but  become  less  evident 
in  advancing  life. 

Every  primary  lobule  of  a  lung  represents 
in  its  structure  the  entire  organ,  and  consists 
of  a  bronchial  tube  opening  into  an  air-passage 
which  communicates  with  a  multitude  of  air-cells. 


FIG.  287. 


DIAGRAM  OF  TWO  PRIMARY  LOBULES 
OF  THE  LUXGS,  magnified.  1,  bron- 
chial tube ;  2,  a  pair  of  primary 
lobules  connected  by  fibro-elastic 
tissue ;  3,  intercellular  air-passages; 
4,  air-cells  ;  5,  branches  of  the  pul- 
monary artery  and  vein. 


The  Air-cells,3  the  ultimate  recesses  of  the  lungs  reached  by  the  air  in 
respiration,  are  rounded  polyhedral  sacs.  They  approach  an  average  of 
about  the  one-tenth  of  a  line  in  diameter,  but  vary  much  in  size,  being 
larger  near  the  surface  than  in  the  deeper  part  of  the  lungs.  They  fur- 
ther increase  in  size  with  the  advance  of  age ;  and  they  become  much 
enlarged  in  asthmatic  persons.  They  communicate  with  a  common, 
somewhat  ramifying,  inter-cellular  air-passage,  which  ends  in  a  bronchial 


1  Lobuli,  or  insulse  pulmonales. 

2  Interlobular  connective,  or  areolar 
tissue. 


3  Cellulee,  or  vesiculee  aerse ;  cellulae 
terminales  and  parietales  ;  alveolae  pul- 
monales; spiramina,  or  cellulae  pulmo- 
num. 


THE   VOCAL   AND  RESPIRATORY   APPARATUS.  453 

tube  emanating  from  a  primary  lobule.  They  are  connected  together  by 
an  intervening  fibro-elastic  tissue,  to  which  the  elasticity  of  the  lungs  is 
mainly  due;  and  they  are  composed  of  a  basement  membrane  with  a 
lining  squamous  epithelium.  Exteriorly  they  are  surrounded  by  fine 
nets  of  capillary  blood-vessels,  which  intervene  between  the  terminal 
branches  of  the  pulmonary  arteries  and  the  commencing  ones  of  the  pul- 
monary veins. 

The  Bron/chial  tubes,1  formed  from  the  subdivision  of  the  two  bron- 
chi, ramify  throughout  the  lungs  without  anastomosing,  and  finally  end 
in  the  primary  lobules,  where  they  communicate  with  the  intercellular 
air-passages.  They  have  the  same  structure  as  the  trachea  and  bronchi, 
except  that  their  cartilages  are  subdivided  into  several  pieces  distributed 
around  the  tube  instead  of  forming  C-like  rings;  and  their  muscular 
fibres  form  a  continuous  layer.  At  the  division  of  the  bronchial  tubes 
the  cartilages  assume  a  crescentic  shape,  and  are  so  placed  as  to  maintain 
the  orifices  of  the  tubes  open.  As  the  bronchial  tubes  become  smaller, 
the  cartilaginous  element  of  structure  decreases,  and  finally  disappears, 
when  they  consist  alone  of  fibro-elastic  membrane  with  muscular  fibres 
and  a  lining  mucous  membrane. 

The  Pulmonary  artery,  specially  devoted  to  the  conveyance  of  dark 
blood  from  the  heart  to  the  lungs,  ramifies  in  company  with  the  bronchi 
and  terminates  in  the  capillary  vascular  nets  inclosing  the  air-cells. 

The  Pul'monary  veins  originate  in  the  capillary  nets  just  mentioned, 
and  pursue  the  course  of  the  bronchial  tubes  until  they  emerge  from  the 
lungs,  when  they  convey  the  aerated,  scarlet  blood  to  the  heart. 

The  Bron/chial  arteries,  which  are  small  vessels  compared  with  the 
preceding,  come  off  from  the  aorta,  and  follow  the  ramifications  of  the 
bronchial  tubes,  the  tissues  of  which  they  chiefly  supply. 

The  Bron/chial  veins,  returning  most  of  the  blood  of  the  correspond- 
ing arteries,  terminate  in  the  azygos  vein  on  the  right,  and  the  superior 
hemiazygos  vein  on  the  left  side. 

The  lymphatics  of  the  lungs  are  numerous.  The  superficial  ones  con- 
verge toward  the  root ;  the  deep  ones  follow  the  course  of  the  bronchial 
tubes;  and  both  enter  numerous  lymphatic  glands  situated  about  the 
bronchi  and  bifurcation  of  the  trachea.  These  bronchial  glands  in  early 
life  do  not  differ  in  appearance  from  those  elsewhere,  but  in  the  advance 
of  age  they  assume  a  darker  color  than  the  lungs,  and  not  unfrequently 
are  found  to  contain  calcareous  deposits. 

The  nerves  of  the  lungs  are  derived  from  the  pneumogastric  with 

1  Bronchi;  syringes,  or  canales  aeriferi. 


454       THE  VOCAL  AND  RESPIRATORY  APPARATUS. 

branches  of  the  sympathetic.  These  nerves  form  the  anterior  and  pos- 
terior pulmonary  plexuses,  of  which  the  latter  is  the  larger,  and  both 
follow  the  course  of  the  bronchi  and  pulmonary  blood-vessels  in  their 
ramifications. 

THE  PLEURA. 

The  Pleu'ra1  is  a  serous  membrane  which  lines  the  sides  of  the  cavity 
of  the  thorax,  and  is  thence  reflected  from  the  root  over  the  correspond- 
ing lung.  It  closely  adheres  to  the  subjacent  structures,  and  in  its  differ- 
ent positions  receives  the  names  of  costal,  diaphragmatic,2  medias'tinal, 
and  pulmonary  pleura.  From  the  root  of  the  lung  a  fold  of  the  mem- 
brane extends  downward  to  the  diaphragm,  and  is  called  the  pulmonary 
ligament.3  The  cavity  of  the  pleura  is  bathed  with  a  thin  serous  secre- 
tion which  lubricates  the  surface  of  the  lungs,  and  thus  facilitates  their 
movements  during  respiration. 

By  the  approximation  of  the  two  pleura?  in  the  median  line,  they  form 
the  mediasti'num,4  or  partition  of  the  thorax,  which  contains  the  heart 
included  within  its  pericardium. 

The  intervals  between  the  two  pleura?  in  front  of,  behind,  above,  and 
that  occupied  by  the  heart,  are  named  from  their  relative  position  the 
anterior,  posterior,  superior,  and  middle  mediastinal  cavities.  Above 
the  middle  of  the  sternum,  for  a  short  distance,  the  two  pleuraa  come 
into  contact  and  are  associated  by  connective  tissue. 

The  Anterior  medias'tinal  cavity5  is  bounded  in  front  by  the  sternum, 
on  each  side  by  the  pleura,  and  is  occupied  by  some  loose  areolar  tissue. 

The  Posterior  medias'tinal  cavity6  is  bounded  behind  by  the  verte- 
bral column,  on  each  side  by  the  pleura,  and  in  front  by  the  pericardium. 
It  contains  the  aorta,  the  azygos  and  hemiazygos  veins,  the  thoracic 
duct,  the  oesophagus,  and  the  pneumogastric  and  splanchnic  nerves. 

The  Superior  medias'tinal  cavity7  is  bounded  on  each  side  by  the 
apex  of  the  pleura,  behind  by  the  vertebral  column,  and  in  front  by  the 


1Pleurum;    pleuroma;    membrana  diaphratton ;  intersepimentum  thoracis; 

pleuritica  succingens ;  m.  p.  costas  sue-  hymen  diaphratton ;  diribitorium. 

cingens;  m.  costalis,  or  subcostalis ;  hy-  5  Anterior  mediastinum ;  cavum  medi- 

popleurios.  astini  anterius ;  mediastinum  pectorale. 

2  Phrenic.  6  Posterior  mediastinum ;  m.  dorsale ; 

3  Ligamentum  pulmonale.  cavum  mediastini  posterius. 

4  Medianum;  mesodne;  mesotoechium ;  7  Superior  mediastinum;  cavum  medi- 
septum,     or     dissipimentum     thoracis ;  astini  superius. 

membrana   thoracem   intersepiens ;    m. 


JHW 


THE   VOCAL  AND  RESPIRATORY  APPARATUS. 


455 


sternum.     It  contains  the  bifurcation  of  the  trachea,  the  oasophagus,  and 
great  blood-vessels  connected  with  the  base  of  the  heart. 

The  Middle  medias'tinal  cavity1  is  occupied  by  the  heart  within  its 
pericardium. 

THE  THYROID  BODY. 

The  Thy'roid  body2  is  a  moderately  soft,  reddish  organ,  of  unknown 
function,  embracing  the  front  and  sides  of  the  upper  extremity  of  the 
trachea,  and  extending  to  the  sides  of  the  larynx.  It  consists  of  a  pair 
of  lateral  lobes  united  at  their  lower  part  by  a  transverse  isthmus.  Its 
outer  surface  is  convex,  and  its  inner  surface  in  contact  with  the  trachea 
and  larynx  is  concave.  It  adheres  to  the  adjacent  parts  by  connective 
tissue,  and  is  covered  by  the  sterno-hyoid,  sterno-thyroid,  and  omo-hyoid 
muscles,  and  is  in  relation  at  its  posterior  borders  with  the  great  blood- 
vessels of  the  neck. 

The  lateral  lobes3  are  oblong  oval,  thicker  below  than  above,  and 
usually  of  unequal  length.  They  commonly  measure  about  two  inches 
long,  and  extend  from  the 
sixth  cartilaginous  ring  of 
the  trachea  to  the  lower 
part  of  the  thyroid  carti- 
lage. From  the  isthmus 
associating  the  lobes,  a 
process4  of  the  body  fre- 
quently extends  upward 
to  the  hyoid  bone,  to  which 
it  is  attached  by  a  fibrous 
band,  occasionally  con- 
taining some  muscular 
fibres.5 

The  weight  of  the  thy- 
roid body  is  ordinarily 
from  one  to  two  ounces, 
but  is  larger  in  the  fe- 
male. It  is  very  liable  to  enlargement,  especially  in  the  latter  sex,  con- 
stituting the  affection  called  goitre. 

The  thyroid  body  is  a  highly  vascular  organ,  invested  with  a  thin,  fib- 


FIG.  288. 


PORTION  OF  THE  THYROID  BODY  IN  SECTION,  highly  magnified,    a. 
fibrous  stroma;  b,  vesicles;  c,  the  epithelium  and  liquid  contents. 


1  Middle  mediastinum ;    cavum  medi- 
astini  medius. 

2  Corpus  thyreoideum  ;  glandula  thy- 
reoidea ;  ganglion  vasculosum. 


3  Cornua  lateralia. 

4  Cornu  medium ;  processus  pyramid- 
alis. 

5  Levator  glandulse  thyreoideae. 


456 


THE  VOCAL   AND  RESPIRATORY  APPARATUS. 


rous  membrane,1  and  composed  of  a  fibrous  stroma,  in  the  meshes  of 
which  a  multitude  of  minute,  closed  vesicles  are  imbedded.  The  vesicles- 
consist  of  a  basement  membrane3  lined  with  an  epithelium  consisting  of 
a  single  layer  of  nucleated  cells ;  and  they  are  filled  with  a  viscid  amber- 
colored  liquid. 

The  arteries  and  veins  of  the  thyroid  body  are  branches  of  the  superior 
and  inferior  thyroids.  The  lymphatics  are  numerous,  and  communicate 
with  the  cervical  glands.  The  nerves  are  derived  from  the  pneumogastric 
and  great  sympathetic. 

THE  THYMUS  BODY. 

The  Thy'mus  body4  is  a  temporary  organ  of  unknown  function,  which 
increases  in  size  from  the  embryonic  period  up  to  two  years  a/ter  birth, 
and  subsequently  dwindles  away.  It  occupies  the  upper  part  of  the 

FIG.  289.  FIG.  290. 


ONE  LOBE  OF  THE   THYMUS  BODY,  WITH   ITS  CAVITY 
LAID  OPEN,  AND  EXHIBITING   THE   LOBULAH   RECESSES. 

The  lower  extremity  of  the  figure  exhibits  the  out- 
lines of  the  lobules. 


SECTION  OF  A  LOBULE  OF  THE  THYMUS  BODY,  magni- 
fied, a,  fibrous  investment  of  the  lobule ;  6,  acini 
penetrated  by  blood-vessels ;  c,  the  lobular  recess. 


anterior  mediastinal  cavity  behind  the  sternum,  and  extends  into  the 
neck,  frequently  to  the  thyroid  gland.  It  rests  upon  the  pericardium, 
aorta,  left  innominate  vein,  and  the  trachea.  It  is  a  flat  triangular  body 


1  Tunica  propria. 

2  Gland  vesicles. 

3  Membrana  propria. 


4  Corpus  thymicum ;  thymus  gland : 
glandula  thymus ;  thymus ;  corpus  in- 
comprehensibile;  the  sweetbread. 


THE  VOCAL   AND   RESPIRATORY  APPARATUS.  457 

consisting  of  a  pair  of  lateral  and  usually  unequal  lobes.  It  is  of  a 
pinkish  cream  color,  and  varies  in  size  and  weight,  not  only  according  to 
age,  but  also  in  different  individuals  of  the  same  age.  At  birth  it  is 
commonly  about  two  inches  long,  one  and  a  half  inches  wide  at  the  lower 
part,  and  two  or  three  lines  thick,  and  its  weight  is  about  half  an  ounce. 

The  thymus  body  is  provided  with  a  thin  investing  fibrous  membrane, 
and  is  composed  of  numerous  compressed  angular  lobules,  associated  by 
connective  tissue,  which  give  it  the  aspect  of  a  racemose  gland.  Each 
lateral  lobe  commonly  exhibits  an  interior  cavity1  of  variable  extent, 
communicating  with  recesses  in  the  lobules.  Further  than  this,  the 
structure  of  the  thymus  body  has  not  been  satisfactorily  determined. 
The  thick  walls  of  the  lobular  recesses  appear  to  consist  of  acini2  or 
coarse  granules,  comparable  to  the  vesicles  of  the  thyroid  body  or  those 
of  racemose-  glands.  The  acini  are  composed  of  free  nuclei  and  nu- 
cleated cells,  and  are  penetrated  by  blood-vessels.  The  recesses  of 
the  lobules  and  the  cavities  of  the  lobes  are  filled  with  a  thick  milk- 
like  liquid,  mingled  with  numerous  nuclei  and  nucleated  cells. 

The  arteries3  of  the  thymus  body  are  derived  from  the  internal  mam- 
mary, pericardiac,  and  inferior  thyroid  arteries.  The  veins  empty  into 
the  left  innominate  vein.  The  lymphatic  vessels  terminate  in  the  inter- 
nal mammary  lymphatics.  The  nerves  are  derived  from  the  pneumogas- 
trics  and  great  sympathetics. 

1  Reservoir  of  the  thymus.  2  Incorrectly  called  cells,  or  vesicles. 

3  Thymic  arteries. 


CHAPTER  IX. 

THE    URINARY   ORGANS. 

THE  urinary  organs  consist  of  the  kidneys,  which  secrete  the  urine ; 
the  ureters  or  excretory  ducts  of  the  former ;  the  bladder,  a  receptacle 
for  the  urine ;  and  the  urethra,  the  canal  through  which  the  latter  liquid 
is  discharged. 

THE  KIDNEYS. 

The  Kidneys1  are  two  glandular  organs,  deeply  situated  in  the  lumbar 
regions,  lying  one  on  each  side  of  the  vertebral  column ;  the  right  a 
little  higher  than  the  left.  They  are  opposite  the  upper  two  or  three 
lumbar  and  the  last  dorsal  vertebra,  inclining  toward  each  other  above, 
and  are  maintained  in  this  position  by  their  vessels,  together  with  a 
quantity  of  loose  areolar  tissue  usually  containing  much  fat.2  Their 
anterior  surface  is  more  convex  than  the  posterior,  and  their  upper  ex- 
tremity is  larger  than  the  lower,  and  has  attached  to  it  the  supra-renal 
body. 

The  right  kidney  in  front  is  in  contact  with  the  liver,  the  descending 
portion  of  the  duodenum,  and  the  ascending  colon ;  the  left  with  the 
spleen,  pancreas,  stomach,  and  descending  colon. 

The  kidneys  are  smooth,  dark  red,  compressed  oval  bodies  with  a 
notch  on  the  inner  side ;  the  form  being  so  characteristic  that  similar 
shaped  bodies  are  commonly  called  kidney-shaped  or  reniform.  They 
vary  in  size,  but  ordinarily  measure  about  four  inches  in  length,  two 
inches  in  breadth,  and  one  inch  in  thickness,  and  weigh  about  four 
ounces. 

The  notch  on  the  inner  side  of  the  kidneys  is  named  the  hilus,3  and 
communicates  with  an  interior  cavity,  the  sinus,  at  which  the  vessels, 
nerves,  and  excretory  duct  of  the  organs  have  their  entrance  and  exit. 

Besides  the  general  envelope  of  areolar  tissue  and  fat,  the  kidneys  are 
furnished  with  a  special  fibrous  coat.4  This  is  a  thin,  moderately  firm, 

1  Renes.     Singular :     ren ;    nephros ;  3  Porta  renis. 

protmesis.  4  Tunica  propria ;  capsula  fibrosa. 

2  Tunica,  or  capsula  adiposa. 

(458) 


THE  URINARY  ORGANS. 


459 


FIG.  291. 


uniform  layer  of  fibrous  tissue  adhering  slightly  to  the  glandular  struc- 
ture beneath.  It  extends  from  the  hilus  into  the  sinus,  and  at  the  bot- 
tom of  this  cavity  becomes  continuous  with  the  fibrous  investment  of  the 
vessels  and  duct  of  the  organs. 

Upon  dividing  a  kidney  in  its  breadth  longitudinally,  the  cut  surface 
is  observed  apparently  to  consist  of  two  substances :  an  exterior  more 
granular  looking  portion, 
named  from  its  relative 
position  the  cortical  sub- 
stance,1 and  an  interior 
striated  portion,  called 
the  med'ullary  sub- 
stance,2 The  latter  is 
arranged  into  conical 
masses,  the  renal  pyra- 
mids,3 the  bases  of  which 
are  enveloped  in  the  cor- 
tical substance,4  while  the 
free  summits,  named  renal 
papillae,5  project  into  the 
sinus  of  the  kidney. 

The  renal  pyramids3 
vary  in  size  and  number — 
there  usually  being  from 
ten  to  fifteen — and  some- 
times a  pair  of  them  are 
confluent.  They  are  ar- 
ranged in  three  irregular 
series,  with  their  bases  directed  exteriorly  and  their  summits  converging 
toward  the  sinus  of  the  kidney.  Together  with  the  enveloping  cortical 
substance  at  their  base,  they  correspond  with  so  many  lobules  which  are 
attached  by  connective  tissue  in  the  foetus,  but  subsequently  become  in- 
dissolubly  blended.  In  many  of  the  lower  animals  the  lobules  remain 
permanently  and  distinctly  separated  ;  and  not  unfrequently  the  surface 
of  the  adult  human  kidney  presents  more  or  less  distinct  traces  of  the 
original  lobular  isolation. 


LONGITUDINAL  SECTION  OF  A  KIDNEY.  1,  cortical  substance;  2,  re- 
nal pyramid ;  3,  renal  papillae ;  4,  pelvis ;  5,  ureter ;  6,  renal  ar- 
tery; 7,  renal  vein;  8,  branches  of  the  latter  vessels  in  the  sinus 
of  the  kidney. 


1  Substantia  corticalis  vasculosa,  glan- 
dulosa,  or  glomerulosa ;   glandular,  se- 
cerning, or  vascular  substance. 

2  Substantia    medullaris,   tubulosa, 
fibrosa,  or  radiata ;  uriniferous,  or  co- 
noidal  substance. 


3  Pyramids  of  Malpighi. 

4  The  cortical  substance  projecting  be- 
tween the  bases  of  the  renal  pyramids 
forms  the  columnae,  or  septa  Bertini. 

5  Papillas,  or  mammillae  renales. 


460 


THE   URINARY   ORGANS. 


FIG.  292. 


The  substance1  of  the  kidney  is  mainly  composed  of  secretory  tubes, 
named  urin/iferous  tubules,2  and  blood-vessels,  associated  with  com- 
paratively little  connective  tissue.  The  terminal  orifices  of  the  urinifer- 
ous  tubules  may  be  observed,  to  the  number  of  several  hundred,  at  the 
summit  of  each  renal  papilla.  Tracing  the  tubules  from  their  terminal 

orifices  backward,  they  are  found  to 
pursue  a  nearly  straight  but  slightly 
divergent  course  in  the  renal  pyra- 
mids, dividing  repeatedly  at  acute 
angles,  and  diminishing  in  size. 
Approaching  the  bases  of  the  pyra- 
mids, they  assume  a  slightly  tor- 
tuous course,  subsequently  become 
much  convoluted,  and  finally  cease 
in  the  cortical  substance,  each  in  a 
pouch-like  dilatation,  inclosing  a 
renal  glom'erule  (Malpighian  cor- 
puscle.) 

The  straight  course  of  the  urin- 
iferous  tubules  in  the  renal  pyra- 
mids, and  their  subsequent  convo- 
luted course,  give  rise  to  the  differ- 
ence of  appearance  in  the  renal 
substance  distinguished  as  the  me- 
dullary and  cortical  portions.  The 
uriniferous  tubules  are  composed 
of  a  delicate  wall  of  basement  mem- 
brane lined  with  a  pavement  epi- 
thelium, and  at  their  pouch-like 
extremity  the  wall  is  inflected  upon 
the  inclosed  renal  glomerule. 

The  kidneys  are  very  vascular, 
and  obtain  their  blood  through  the 
renal  arteries,  which  are  large  in 
proportion  with  the  organs  they 
supply.  Approaching  the  hilus  of  a  kidney,  the  renal  artery  divides 
into  several  branches,  which  subdivide,  enter  the  sinus,  and  penetrate 


DIAGRAM  OF  THE  STRUCTURE  OF  THE  KIDNEYS.  1, 
two  uriniferous  tubules  of  the  cortical  substance 
lined  with  a  pavement  epithelium;  2,  dilatation  of 
a  tubule  inclosing  a  renal  glomerule ;  3,  branch  of 
the  renal  artery  ending  in  vessels  which  enter  the 
glomerules  as  seen  at  4,  5 ;  6,  knot  of  blood-vessels 
freed  from  its  investment;  7,  veins  emerging  from 
the  vascular  knots ;  8,  plexus  formed  by  the  latter 
veins  among  the  uriniferous  tubules,  from  which 
plexus  originate  the  branches  of  the  renal  vein. 


1  Secreting  parenchyma. 

2  Tubuli  uriniferi ;  uriniferous  canals. 
Those  of  the  medullary  substance  are 
named    tubuli    recti,   or  Belliniani,    or 
ducts  of  Bellini.     The  bundles  formed 


by  the  divisions  of  these  tubes  are  called 
the  pyramides  Ferreinii.  The  urinifer- 
ous tubules  of  the  cortical  substance  are 
the  tubuli  contorti,  corticales,  or  Ferre- 
inii. 


THE   URINARY   ORGANS.  461 

the  renal  substance  between  the  renal  papillae.  Ramifying  through  the 
cortical  substance,  they  finally  terminate  by  forming  most  remarkable 
plexuses,  named  the  renal  glom/erules.1  Each  glomerule  is  a  spheroidal 
knot  of  about  TJo  of  an  inch  in  diameter,  consisting  of  an  intricate  and 
close  convolution  of  capillary  vessels,  inclosed  by  the  pouch-like  dilata- 
tion of  a  uriniferous  tubule.  From  each  glomerule  there  emerges  an 
efferent  vessel,  which,  together  with  others,  forms  a  capillary  net-work 
between  and  along  the  course  of  the  uriniferous  tubules.  From  this 
capillary  net-work  the  renal  veins  originate  and  converge  from  the  ex- 
terior surface  of  the  kidney  toward  the  base  of  the  renal  pyramids ; 
then  pursue  the  course  of  the  arteries  and  emerge  into  the  sinus  of  the 
kidney,  from  which  they  make  their  exit  in  a  single  trunk. 

The  excretory  duct  of  the  kidney,  called  the  ure'ter,  appears  at  the 
hilus  as  a  compressed  funnel-shaped  pouch,  named  the  pelvis.2  Within 
the  sinus,  the  wide  mouth  of  the  pelvis  divides  into  two  or  three  por- 
tions, which  subdivide  into  several  smaller  funnels,  or  cal'yces.3  Into 
each  cal'yx  one  or  two  renal  papillae  project,  so  that  the  urine  dribbling 
from  the  orifices  of  the  uriniferous  tubules  is  received  by  the  calyces, 
conveyed  to  the  pelvis,  and  thence  runs  down  the  ureter. 

The  cal'yces,  pelvis,  and  ure'ter  have  the  same  structure,  consisting 
of  an  exterior  fibrous  layer,  a  succeeding  stratum  of  unstriated  muscular 
fibres,  and  a  lining  mucous  membrane.  The  fibrous  layer  of  the  calyces 
at  the  base  of  the  renal  papilla  becomes  continuous  with  the  fibrous 
investment  of  the  sinus  of  the  kidney.  The  muscular  layer  thins  away 
from  the  pelvis,  and  ceases  at  the  base  of  the  renal  papillae,  while  the 
mucous  membrane  is  reflected  upon  the  latter  and  becomes  continuous 
with  the  uriniferous  tubules  at  their  orifices. 

In  the  hilus  and  sinus  of  the  kidney,  the  pelvis  is  posterior  to  the 
position  of  the  renal  blood-vessels.  The  renal  vein  is  in  advance  of  the 
corresponding  artery  at  the  hilus,  but  within  the  sinus  their  branches 
intermingle.  The  nerves  of  the  kidney  are  derived  from  the  renal  plexus 
of  the  sympathetic  system ;  the  lymphatics  communicate  with  the  lumbar 
glands. 

The  Ure'ter4  is  a  cylindrical  tube  from  each  kidney,  which  conveys  the 

1  Glomeruli  renales ;  corpuscula  Mai-  3  Infundibula ;  calyces  renales  minores 
pighii ;    corpora    Malpighiana;    Malpi-  et   majores;   canales,  or  cylindri  mem- 
ghian  bodies  or  corpurcles ;   glandules,  branacei  renum ;  tubuli  pelvis  renum ; 
glomerules,  or  acini  of  Malpighi.  fistulae  ureterum  renum. 

2  Pelvis    renalis;     sinus,    venter,    or  4  Ductus  urinse ;  vas  urinarium;  ura- 
alvus  renum.  na :   canalis  nerveus  fistulosus  renum ; 

vena  alba  renum. 


462  THE  URINARY  ORGANS. 

urine  to  a  common  receptacle,  the  bladder.  It  measures  from  fifteen  to 
eighteen  inches  long,  and  is  about  the  diameter  of  a  goose-quill.  De- 
scending obliquely  inward,  it  enters  the  pelvic  cavity  and  curves  forward 
and  downward  to  the  fundus  of  the  bladder,  into  which  it  opens.  In 
its  course  it  lies  behind  the  peritoneum,  loosely  attached  to  contiguous 
parts  by  areolar  tissue,  and  is  crossed  in  front  by  the  spermatic  vessels. 
First  resting  on  the  psoas  muscle,  it  then  crosses  the  iliac  blood-vessels, 
and  is  afterwards  included  by  the  recto-vesical  or  recto-uterine  fold  of 
the  peritoneum,  according  to  the  sex.  Approaching  the  bladder,  in  the 
male  it  crosses  to  the  outer  side  of  the  spermatic  duct,  in  the  female  runs 
along  the  side  of  the  neck  of  the  uterus,  and  terminates,  after  penetrat- 
ing the  wall  of  the  bladder  obliquely,  about  one  and  a  half  inches  be- 
hind the  orifice  of  the  urethra,  and  about  the  same  distance  from  its 
fellow. 

The  fibrous  coat  of  the  ureter  is  strong,  and  pinkish  white  in  color. 
The  muscular  coat,  consisting  of  pale,  unstriated,  longitudinal  and  trans- 
verse fibres,  slightly  thickens  in  its  descent.  The  mucous  membrane  is 
without  glands,  and  is  provided  with  an  epithelium  whose  cells  exhibit  a 
remarkable  variety  in  form  and  size. 

The  arteries  of  the  pelvis  and  ureter  are  small  branches  derived  from 
the  renal,  spermatic,  and  vesical  arteries.  The  nerves  are  derived  from 
the  sympathetic  system. 

The  ll'rine,  secreted  by  the  kidneys  and  accumulated  in  the  bladder,  is 
a  transparent,  amber-colored  liquid,  highly  complex  in  its  chemical  com- 
position. Its  most  characteristic  constituent  is  a  peculiar  nitrogenized 
principle  called  u'rea. 

THE  URINARY  BLADDER. 

The  U'rinary  Bladder1  is  a  musculo-membranous  sac  which  serves  as 
a  reservoir  to  the  urine  as  it  is  excreted  by  the  kidneys.  Its  size  and 
form  vary  with  its  condition  of  distention  or  collapse.  When  empty,  it 
lies  in  the  pelvic  cavity,  appearing  as  a  flattened,  triangular  body,  with 
the  apex  extending  upward  behind  the  pubic  symphysis.  When  moder- 
ately distended,  it  assumes  a  rounded  form,  and  still  occupies  the  pelvic 
cavity ;  but  when  completely  filled,  it  becomes  ovoidal,  and  its  summit  ex- 
tends above  the  pubes  into  the  pre-peritoneal  space  of  the  hypogastric 
region.  Its  long  diameter  is  directed  from  the  latter  downward  and 
backward  toward  the  anus  ;  but  from  its  summit  to  its  termination  in  the 
urethra  its  axis  is  somewhat  curved. 

1  Vesica  urinaria;  bladder;  urocystis;  cystis. 


THE  URINARY  ORGANS.  463 

In  the  female  the  bladder  approaches  a  more  spheroidal  form  than  in 
the  male,  and  in  both  sexes  its  capacity  is  about  equal  to  one  pint. 

The  upper  extremity  or  summit1  of  the  bladder  is  connected  with  a 
fibrous  cord  ascending  behind  the  linea  alba  to  the  umbilicus.  This 
cord  is  an  obliterated  tube,  the  urachus,  which  in  the  embryo  extends 
between  the  bladder  and  a  pouch,  named  the  allantois,  situated  exteriorly 
to  the  abdomen. 

The  base  or  fundus2  of  the  bladder  is  the  widest  part  of  the  organ, 
and  is  in  contact,  in  the  male,  with  the  lower  end  of  the  rectum ;  in  the 
female,  with  the  vagina. 

The  portion  of  the  bladder  intervening  to  the  fundus  and  summit  is 
the  body,  and  is  more  convex  in  front  than  behind. 

In  advance  of  the  fundus,  the  bladder  is  narrowed  in  a  funnel-like 
manner,  and  is  named  the  neck.3  In  the  male  this  is  nearly  horizontal, 
the  fundus  extending  slightly  below  its  level;  but  in  the  female  the 
neck  descends  obliquely  forward  and  is  the  lowest  part  of  the  organ. 

The  bladder  is  maintained  in  position  by  reflections  of  the  peritoneum 
and  recto-vesical  fascia,  by  connective  tissue  attaching  its  front  and  fun- 
dus to  the  contiguous  organs,  by  the  obliterated  umbilical  arteries  and 
urachus,  and  by  the  neck  becoming  continuous  with  the  urethra. 

The  recto-vesical  fascia  passing  from  the  back  of  the  pubis  to  the 
prostate  gland  and  neck  of  the  bladder  forms  two  small  processes,  named 
the  anterior  ligaments  of  the  bladder.  A  continuation  of  these  to  the 
sides  of  the  fundus,  reflected  from  the  inner  surface  of  the  anal  elevator 
muscles,  constitutes  the  lateral  ligaments  of  the  bladder, 

The  so-called  false  ligaments  of  the  bladder  are  folds  of  peritoneum 
produced  in  its  reflection  upon  this  viscus.  The  recto'vesical  folds4  pass 
from  the  sides  of  the  rectum  to  the  sides  of  the  bladder ;  or  instead  of 
them,  in  the  female,  the  utero-vesical  folds  pass  from  the  sides  of  the 
uterus  to  the  sides  of  the  bladder.  These  folds  contain  the  ureters,  ves- 
sels and  nerves  of  the  bladder,  and  the  commencement  of  the  obliterated 
umbilical  arteries.  A  slight  fold  is  also  produced  by  the  subsequent 
course  of  the  latter  together  with  the  urachus,  toward  the  umbilicus. 

The  peritoneum  is  reflected  from  the  rectum  or  uterus  to  the  back,  the 
sides,  and  the  summit  of  the  bladder,  and  thence  to  the  sides  of  the  pel- 
vis5 and  the  anterior  parietes  of  the  abdomen.  Where  destitute  of  peri- 
toneum, the  bladder  is  invested  with  a  thin,  feeble  layer  of  fibrous  tissue, 

1  Superior  fundus.  5  The  reflections  to  the  side  of  the  pel- 

2  Inferior  fundus ;  bas-fond.  vis  constitute  the  lateral  false  ligaments 

3  Cervix.  of  the  bladder. 

4  Plicae  semilunares. 


464  THE   URINARY   ORGANS. 

constituting  a  portion  of  the  recto-vesical  fascia  and  continuous  with  the 
subserous  connection  of  the  former.  When  the  bladder  becomes  dis- 
tended, its  summit  elevates  the  peritoneum  from  the  abdominal  wall  in 
the  hypogastric  region,  so  that  the  organ,  in  an  operation,  may  be  reached 
above  the  pubis  without  interfering  with  the  latter  membrane. 

Succeeding  the  peritoneum  and  vesical  fascia,  the  bladder  possesses  a 
strong  muscular  coat,  consisting  of  reddish-brown  unstriated  fibres 
which  are  collected  into  various  sized  fasciculi  conjoining  in  a  reticular 
manner,  and  are  arranged  in  two  different  directions.  The  external 
longitudinal  fibres  diverge  from  the  neck  and  anterior  ligaments  of  the 
bladder,  and  again  converge  to  its  summit  about  the  attachment  of  the 
urachus.  The  internal  circular  fibres  are  less  numerous  than  the  former, 
are  transverse  and  oblique  ;  and  at  the  neck  of  the  bladder  accumulate 
in  a  dense  bundle,  constituting  the  vesical  sphincter,1 

Succeeding  the  muscular  coat,  and  adhering  closely  to  it,  the  bladder 
is  provided  with  a  moderately  thick,  strong,  and  extensible  layer  of 
fibrous  tissue  mingled  with  elastic  fibres. 

The  lining  mucous  membrane  of  the  bladder  is  smooth,  pale  rose  red, 
and  closely  adherent  to  the  fibrous  layer  beneath.  It  has  an  epithelium, 
like  that  of  the  ureters  and  pelves  of  the  kidneys,  consisting  of  several 
layers  of  cells,  of  which  the  deeper  ones  are  columnar,  and  the  superficial 
ones  larger  and  tessellated.  In  the  neck  of  the  bladder  it  is  also  pro- 
vided with  a  few  minute  racemose  glands. 

In  the  empty  condition  of  the  bladder  its  mucous  membrane  is  thrown 
into  wrinkles,  which  disappear  as  the  organ  undergoes  distention.  Some- 
times it  presents  reticular  ridges  corresponding  with  the  arrangement 
of  the  fasciculi  of  the  muscular  coat ;  a  condition  usually  due  to  inordi- 
nate action  of  the  latter  arising  from  obstruction  to  the  emission  of  the 
urine. 

At  the  bottom  of  the  bladder,  extending  from  the  neck  toward  the 
fundus,  a  slightly  elevated  triangular  space  is  observable,  named  the 
vesical  triangle.2  The  apex  of  this  constitutes  the  vesical  uvula,3  a 
small,  rounded  elevation  projecting  into  the  orifice  of  communication  of 
the  bladder  with  the  urethra.  The  basal  angles  of  the  vesical  triangle 
are  formed  by  the  orifices  of  the  ureters,  which  appear  as  oblique  slits 
the  one-eighth  of  an  inch  long.  The  muscular  structure4  beneath  the 
mucous  membrane  of  the  vesical  triangle  is  thick,  and  often  presents 
fasciculi5  diverging  from  the  vesical  uvula  to  the  orifices  of  the  ureters. 

1  Musculus  sphincter  vesicse.  3  Uvula  vesicee. 

2  Trigonum  vesicse  ;  t.  Lieutaudi ;  cor-          4  Muscle  of  the  vesical  triangle, 
pus  trigonum.  5  Muscles  of  the  ureters. 


THE    URINARY  ORGANS. 


THE   URETHRA. 

The  TJre'thra1  in  the  male  serves  as  a  passage  for  the  urine  and  the 
spermatic  liquid.  As  its  anatomical  relations  may  be  best  understood 
after  describing  the  penis,  an  account  of  it  is  reserved  for  the  chapter  on 
the  organs  of  generation. 

The  Ure'thra  of  the  female  serves  alone  for  the  passage  of  the  urine. 
In  consequence  of  the  divided  condition  of  the  spongy  body  of  the  cli- 
toris it  does  not  extend  through  this  organ,  as  the  male  urethra  does 
through  the  spongy  body  of  the  penis  ;  and  it  therefore  corresponds  only 
with  the  prostatic  and  membranous  portions  of  the  urethra  of  the  male. 
It  is  about  an  inch  and  a  half  long  and  three  or  four  lines  wide,  though 
it  is  capable  of  greater  distention.  From  the  bladder  it  curves  down- 
ward and  forward  beneath  the  pubic  arch,  and  terminates  at  the  middle 
of  the  base  of  the  vestibule  just  above  the  orifice  of  the  vagina.  It  lies 
imbedded  in  the  anterior  wall  of  the  latter  canal,  and  pierces  the  trian- 
gular ligament,  its  external  orifice2  being  indicated  by  a  slight  papillary 
eminence  about  an  inch  behind  the.  glans  of  the  clitoris  or  twice  that 
distance  from  the  anterior  commissure  of  the  vulva. 

The  lining  mucous  membrane  of  the  urethra  is  longitudinally  folded, 
reddish,  and  provided  with  minute  racemose  glands.3  Its  epithelium  is 
squamous  toward  the  external  orifice,  and  assumes  the  character  of  that 
of  the  bladder  toward  its  inner  orifice.  Exterior  to  the  mucous  mem- 
brane is  a  layer  of  fibrous  tissue  containing  many  blood-vessels,  especially 
veins  forming  a  plexus.  The  urethra  is  also  furnished  with  a  layer  of 
unstriated  muscular  fibres  mingled  with  elastic  and  fibrous  tissue. 

THE  SUPRA-RENAL  BODIES. 

The  Supra-re'nal  bodies4  are  a  pair  of  flattened  triangular  organs, 
situated  one  upon  the  upper  extremity  of  each  kidney,  and  inclined  in- 
wardly toward  the  vertebral  column.  Their  upper  border  is  thin  and 
convex  ;  their  lower  border  or  base  is  thick  and  concave,  and  is  attached 
by  long,  loose  areolar  tissue  to  the  corresponding  kidney.  Their  poste- 
rior surface,  moderately  convex,  rests  against  the  crura  of  the  diaphragm ; 
their  anterior  surface,  more  flat,  on  the  right  side  is  in  contact  with  the 
liver,  on  the  left  side  with  the  pancreas  and  spleen.  The  surfaces  present 

1  Meatus,  or  ductus  urinarius.  glandulee  supra-renales ;  capsulge  atra- 

2  Meatus  urinarius  ;  urethral  orifice.  biliariae,   renales,  or  supra-renales ;  re- 

3  Glands  of  Littre.  nal  glands,  or  capsules ;  renes  succentu- 

4  Supra-renal    capsules,    or    glands;  riati;  nephridi. 

30 


466 


THE   URINARY  ORGANS. 


vascular  furrows,  the  largest  of  which  at  the  base  is  distinguished  as 
the  hilus. 

The  supra-renal  bodies  are  brownish  yellow  in  color,  of  moderately 
firm  consistence,  and  vary  in  size  in  different  individuals,  and  slightly  on 
the  two  sides.  Generally  they  are  about  one  and  a  half  inches  in  breadth 
and  height,  and  about  one-fourth  of  an  inch  thick.  Besides  a  quantity 
of  loose  areolar  tissue,  often  mingled  with  fat,  connecting  them  with 
contiguous  parts,  they  have  a  thin  but  strong  fibrous  coat. 

When  a  section  is  made  across  the  supra-renal  bodies,  they  are  found 
to  be  composed  of  an  external  layer,  named  the  cortical  substance,  and 
an  internal  softer  material,  the  medullary  substance. 


FIG.  293. 


FIG.  294. 


SECTION  OF  THE  CORTICAL  SUBSTANCE  OF  A  SUPRA- 
RENAL BODY,  highly  magnified,  a,  stroma  of  fibrous 
tissue;  6,  oblong  oval  receptacles  occupied  by 
groups  of  cells. 


CELLS  FROM  THE  SUPRA-RKNAL  BODY,  highly  mag- 
nified, a,  nucleated  cells  from  the  cortical  sub- 
stance; 6,  c,  d,  cells  from  the  same  containing  fat; 
e,  cells  from  the  medullary  substance. 


The  cor'tical  layer1  is  yellow  in  color,  of  moderately  firm  consistence, 
and  is  striated,  or  presents  a  columnar  appearance  at  right  angles  to  the 
surfaces  of  the  layer.  Examined  with  the  aid  of  the  microscope,  it  ex- 
hibits oblong  receptacles  occupying  a  fibrous  stroma  continuous  with  the 
fibrous  coat  of  the  body.  These  receptacles  have  their  long  diameter 
vertical  to  the  surface  of  the  cortical  substance,  and  are  filled  with  fine 
granular  matter,  nuclei,  oil  globules,  and  pigment  granules.  According 
to  Kolliker,  all  of  these  elements  are  the  contents  of  groups  of  cells  oc- 
cupying the  receptacles  of  the  cortical  stroma. 

The  med'ullary  substance2  is  a  dark-brown,  pulpy  matter,  so  easily 
broken  that  the  cavity  frequently  observed  in  its  interior  is  usually 
viewed  as  being  an  accidental  laceration.  It  consists  of  a  fine  stroma  of 
areolar  tissue  continuous  with  that  of  the  cortical  substance,  and  con- 
taining in. its  meshes  fine. granular  matter,  pigment  granules,  oil  globules, 
and  nucleated  cells  somewhat  resembling  those  of  the  nerve  centres. 


1  Substantia  corticalis  ;  cortex. 


2  Substantia  medullaris. 


THE   URINARY  ORGANS.  467 

The  blood-vessels  of  the  supra-renal  bodies  are  numerous.  Each  is 
supplied  by  the  supra-renal  artery  from  the  aorta,  together  with  branches 
from  the  contiguous  phrenic  and  renal  arteries.  Upon  entering  the 
organ  the  arteries  ramify  through  its  fibrous  stroma,  and  terminate  in 
capillaries  surrounding  the  receptacles  of  granular  and  cell  contents. 
The  veins  emanating  from  the  organ  usually  form  a  single  trunk,  which 
terminates  on  the  right  in  the  inferior  cava,  on  the  left  in  the  correspond- 
ing renal  vein.  Few  lymphatics  have  been  noticed.  The  nerves  are 
chiefly  derived  from  the  solar  and  renal  plexuses  of  the  sympathetic 
system,  and  are  so  numerous  as  to  have  given  rise  to  the  impression  that 
the  supra-renal  bodies  may  have  some  important  function  in  connection 
with  the  nervous  system,  otherwise  the  use  of  these  organs  remains 
totally  unknown. 


CHAPTER  X. 

THE    GENERATIVE    APPARATUS. 

THE  MALE  ORGANS  OF  GENERATION. 

THE  organs  of  generation  of  the  male  consist  of  the  testicles  and 
penis,  together  with  certain  accessories. 

THE  TESTICLES. 

The  Testicles1  are  two  glandular  bodies  which  secrete  the  spermatic 
liquid,  and  are  suspended  within  the  scrotum,  one  on  each  side,  by  the 
spermatic  cords. 

The  Scro'tum2  is  the  pendant  pouch  below  the  pubes,  containing  the 
testicles.  The  skin  of  the  scrotum  is  thin,  darker  than  elsewhere,  and 
more  or  less  wrinkled.  It  is  marked  in  the  median  line  by  a  slight 
ridge,  the  raphe,  which  is  continued  forward  on  the  under  part  of  the 
penis,  and  backward  to  the  anus,  and  is  an  indication  of  original  separa- 
tion of  the  two  halves  of  the  scrotum  in  the  embryo.  From  the  surface 
of  the  skin  project  scattered  crisp  hairs,  whose  roots  are  surrounded  by 
groups  of  sebaceous  glands,  appearing  as  whitish  eminences  on  the 
scrotum. 

The  inner  portion  of  the  skin  of  the  scrotum  is  composed  of  pale-red, 
unstriated  muscular  fibres,  constituting  the  dar'tos.3  This  structure 
fades  away  at  the  borders  of  the  scrotum  into  the  neighboring  superficial 
fascia.  In  the  median  line,  mixed  with  fibrous  tissue,  it  forms  the  scro'- 
tal  partition,4  which  divides  the  scrotum  into  two  recesses  lodging  the 
testicles. 

Upon  the  presence  of  the  dartos  depends  the  contractility  of  the 

1  Testiculi ;  testes  ;    sing. :  testiculus ;       lis  ;  folliculus  genitalis  ;  the  purse ;   the 
testis;  t.  virilis;  orchis;    didymus ;  po-       cods;  the  bags. 

mum    amoris ;     hernia  ;     pi. :     gemini ;  3  Tunica  dartos  ;  t.  muscularis  ;  t.  ru- 

stones,  bicunda     scroti;     membrana    carnosa ; 

2  Scortum ;  scorium  ;  oschus ;  marsu-  marsupium  musculosum. 
pium  ;  bursula;  bursa  testium ;  b.  viri-  4  Septum  scroti. 

(468) 


THE  GENERATIVE  APPARATUS.  469 

scrotum ;  and  ordinarily,  under  the  influence  of  cold,  it  is  observed  to 
throw  the  skin  on  each  side  of  the  raphe  into  transverse,  corrugated 
wrinkles  ;  but  from  the  impression  of  warmth  it  becomes  relaxed  and  the 
scrotum  elongates. 

The  Spermat'ic  cord1  consists  of  the  excretory  duct,  blood-vessels, 
lymphatics,  nerves,  and  cremaster  muscle  of  each  testicle.  From  the  in- 
ternal abdominal  ring  it  pursues  its  course  through  the  inguinal  canal 
and  external  abdominal  ring  downward  to  the  back  part  of  the  testicle. 

The  constituents  of  the  spermatic  cord  and  the  testicle  are  enveloped 
in  an  abundance  of  areolar  tissue,  the  spermatic  fascia,2  which  ifc  con- 
tinuous at  the  abdomen  with  the  superficial  and  transverse  fasciae.  In- 
volved between  the  layers  of  the  spermatic  fascia  are  the  thin,  scattered 
fasciculi  of  the  cremas'ter  muscle.3  This  arises  within  the  inguinal 
canal,  from  Poupart's  ligament  and  the  spine  of  the  pubis,  and  descends 
along  the  spermatic  cord  to  end  in  loops  upon  the  testicle.  It  is  com- 
posed of  striated  fibres,  and  acts  in  raising  the  testicles;  in  some  indi- 
viduals being  under  the  control  of  the  will. 

Succeeding  the  spermatic  fascia,  the  testicle  is  inclosed  in  a  serous 
membrane,  the  vag'inal  tunic.4  This,  after  investing  the  organ  and  ad- 
hering closely  to  it,  is  reflected  from  its  back  part  so  as  to  form  a  sac, 
the  cavity  of  which  contains  a  serous  liquid  secreted  by  the  vaginal 
tunic.  The  outer  part  of  the  latter  is  loosely  attached  to  the  spermatic 
fascia,  except  at  the  lower  part  of  the  testicle,  where  a  broad  band  of 
areolar  tissue  connects  it  more  firmly  with  the  bottom  of  the  scrotum. 
This  band  is  the  remains  of  the  gubernac'ulum  of  the  testicle,5  a  struc- 
ture of  foetal  life,  apparently  intended  to  determine  the  future  position 
of  the  organ  with  which  it  is  attached. 

The  Testicles,  connected  with  the  spermatic  cords,  hang  obliquely, 
their  upper  extremity  being  directed  forward  and  outward ;  and  the  left 
one  usually  is  lower  than  the  right  one.  They  are  oval,  laterally  com- 
pressed, measure  about  an  inch  and  a  half  long,  and  weigh  each  about 
three-fourths  of  an  ounce. 

Each  testicle  consists  of  an  anterior  oval  body,  properly  named  the 
testis,  and  a  posterior  elongated  portion  clasping  the  former,  and  called 

1  Funiculus   spermaticus ;    testicular       rium   testis;    elevator   testiculi;    tunica 
cord ;  corpus  varicosum.  erythroides. 

2  Spermatic  fascia  in  part ;  tunica  va-  4  Tunica  vaginalis  ;   t.  v.  propria ;  t. 
ginalis  communis  testis.                                  adnata  testis  and  t.  v.  reflexa. 

3  Musculus    cremastericus   testis,    or  5  Gubernaculum   testis  ;    g.  Hunteri ; 
testicondus ;  suspendiculum ;  suspense-      ligamentum  suspensorium  testis. 


470 


THE  GENERATIVE  APPARATUS. 


the  epidid'ymis,1  The  upper  extremity  of  this,  named  the  head,2  is  the 
larger,  and  closely  adheres  to  the  contiguous  part  of  the  testis  ;  its  lower 
extremity,  or  tail,3  loosely  adheres  to  the  latter,  and  turns  upward  on 
itself  to  become  the  spermatic  duct.  The  portion  of  the  epididymis 
between  its  head  and  tail  is  the  body,  and  is  separated  from  the  testis  by 
an  interval  into  which  the  vaginal  tunic  is  reflected. 

FIG.  295. 


TESTICLE,  WITH  THE  VAGINAL  TUNIC  LAID  OPEN.  1, 
lower  part  of  the  spermatic  cord ;  2,  body  of  the 
testicle ;  3,  body,  and  4,  tail,  of  the  epididymis ;  5, 
reflected  portion  of  the  vaginal  tunic. 


TRANSVERSE  SECTION  OF  THE  TESTICLE,  a,  sper- 
matic fascia;  b,  reflected  portion  of  the  vaginal 
tunic ;  c,  cavity  of  the  latter ;  d,  investing  portion 
of  the  same  membrane ;  e,  albugineous  tunic ;  /, 
vaginal  and  albugineous  tunics  of  the  epididymis ; 
g,  its  interior  tubular  structure ;  h,  mediastinum ; 
i,  branches  of  the  spermatic  artery ;  k,  spermatic 
vein ;  I,  spermatic  duct ;  m,  artery  of  the  latter ; 
n,  lobules  of  the  testis ;  o,  septula  separating  the 
latter. 


The  testis  is  invested  with  a  dense,  white  membrane,  the  albugin/eous 
tunic,4  which  is  composed  of  interlacing  bundles  of  fibrous  tissue,  and 
serves  by  its  strength  to  protect  the  soft  glandular  structure  within.  At 
the  upper  part  of  the  testis  it  is  continuous  with  a  thinner  investment  of 
the  same  kind  on  the  epididymis ;  and  at  the  back  part  forms  a  process 
named  the  mediastinum.5  This  projects  into  the  glandular  substance  of 
the  testis  so  as  to  produce  an  incomplete  vertical  partition,  and  from  it 
diverge  numerous  fibrous  bands,  named  sep'tula,6  which  are  inserted  into 
the  inner  surface  of  the  albugineous  tunic,  and  serve  to  sustain  the  deli- 
cate secretory  structure  of  the  organ. 


1  Didymis  ;  parastata ;  testiculus  ac- 
cessorius ;  caput  testis ;  corpus  varico- 
sum  testis  ;  supergeminalis. 

'2  Globus  major;  caput. 

3  Globus  minor ;  cauda. 


4  Tunica  albuginea  ;  peritestis  ;  dura 
mater  testis ;  membrana  capsularis  tes- 
tis ;  albuginea  testis  ;  perididymis. 

5  M.   testis;     corpus    Highmori,    or 
Highmorianum ;  meatus  seminarius. 

6  Septula  testis. 


THE   GENERATIVE   APPARATUS. 


471 


FIG.  297. 


Upon  the  inner  surface  of  the  albugineous  tunic,  mediastinum,  and 
septula  is  spread  a  delicate  vascular  tunic,1  formed  by  the  spermatic 
blood-vessels,  which  pass  to  and  from  the  testis  through  the  mediastinum. 
The  vascular  tunic  holds  the  same  relation  to  the  secretory  substance 
of  the  testicle  that  the  pia  mater  does  to  the  brain ;  that  is  to  say,  it  is 
the  point  of  departure  and  termination  of  the  capillary  blood-vessels  of 
the  organ. 

The  Glandular  structure  of  the  testis  is  a  soft,  reddish-yellow,  in- 
elastic mass,  divided  into 
several  hundred  pyramidal 
or  conoidal  lobules,2  which 
converge  toward  the  medi- 
astinum. Each  lobule  con- 
sists of  from  one  to  three 
seminiferous  tubules,3 
occasionally  branching 
and  exceedingly  convo- 
luted. At  the  narrow 
extremity  of  the  lobules 
the  tubules  end  in  straight 
tubes,4  which  enter  the 
mediastinum  and  form  to-  6 

gether  within  its  length  a 
reteform  plexus,5  From 
the  upper  part  of  this 
plexus  about  a  dozen  ef- 
ferent canals6  emerge  and 
pass  out  of  the  testis  to 
the  head  of  the  epididy- 
mis.  Within  the  latter  TESTICLE,  DEPRIVED  OF ITS  TUNICS<  a,  body  of  the  testicle,  or  the 

the  efferent  Canals  become      testis;  b,  lobules;  c,  position  at  which  they  end  in  the  straight 

convoluted  into  a  series    tubes;  d: retefo;rm plexus ;  e' efferent canals;/' 8permatic  cone8' 

g,  epididymis ;  n,  commencement  of  spermatic  duct;  i,  a  spermatic 

of    Spermatic    COneS.7     cone  unattached  to  the  testis ;  m,  n,  branches  of  the  spermatic  ar- 
These  Successively  end  in     tery '  °'  deferent  ar*ery;  p,  anastomosis  between  the  two  latter 

a  single,  coarse,  and  much 

convoluted  tube  forming  the  body  and  tail  of  the  epididymis,  which 

finally  terminates  in  the  straight  spermatic  duct, 


1  Tunica  vasculosa. 

2  Lobuli  testis. 

3  Tubuli  or  canaliculi  seminiferi;  sem- 
inal tubes  or  canaliculi ;  vasa  seminalia ; 
vascula  serpentina. 


4  Vasa,  or  ductuli  recti. 

5  Plexus  reteformis  ;  rete  vasculosum 
testis  ;  r.  v.  Halleri. 

6  Vasa  efferentia. 

7  Coni  vasculosi;  c.  v.  Halleri. 


472  THE  GENERATIVE  APPARATUS. 

Usually  there  is  a  spermatic  cone  joining  the  epididymis  below  the 
others,  which  has  no  connection  with  the  testis.1 

The  seminiferous  tubules  are  about  one-tenth  of  a  line  in  diameter, 

and  are  composed  of  a  basement 

IG'  "  '  membrane  strengthened  with  a  deli- 

cate layer  of  fibrous  tissue,  and 
lined  with  soft,  polyhedral  secret- 
ing cells.  These,  which  are  named 
sperm  cells,  elaborate  the  spermat'- 
ic  or  sem/inal  liquid,  the  peculiar 
secretion  of  the  testicles.  The 
contents  of  the  cells,  besides  the 
nucleus,  consist  of  finely  granular 
matter,  which  subsequently  assumes 
the  form  of  bundles  of  filamentary 
bodies,  named  spermatozo'ids.  The 

PORTION  OF  A  SEMINIFEROUS  TUBULE,  highly  mag- 
nified,   a,  fibrous  coat;  6,  basement  membrane  ;c,        Cells     are     Constantly    Cast    off    aild 
spermatic  cells.  burgt>  whUe  otherg   are  successively 

developed. 

The  canal  of  the  epididymis,  besides  an  external  layer  of  fibrous  tis- 
sue, is  provided  with  unstriated  muscular  fibres ;  and  its  lining  membrane 
has  a  columnar  epithelium. 

The  Spermatic  duct,  or  vas  deferens,2  is  the  excretory  duct  of  the 
testicle.  It  is  a  cylindrical  tube,  about  a  foot  and  a  half  in  length  and 
from  a  line  to  a  line  and  a  half  in  diameter.  From  the  tail  of  the  epi- 
didymis it  ascends  along  the  inner  side  of  the  latter  and  forms  one  of 
the  constituents  of  the  spermatic  cord,  in  which  it  lies  behind  the  blood- 
vessels, and  is  readily  distinguished  by  its  wire-like  feel.  Having  passed 
through  the  inguinal  canal,  it  leaves  the  spermatic  vessels  at  the  internal 
abdominal  ring  and  descends  into  the  pelvis.  Reaching  the  side  of  .the 
bladder,  it  curves  backward  and  downward  beneath  the  fundus,  and 
passes  forward  in  a  convergent  manner  to  form,  in  conjunction  with  the 
duct  of  the  seminal  vesicle,  the  ejaculatory  duct. 

The  walls  of  the  spermatic  duct  are  exceedingly  thick,  and  its  calibre 
is  about  equal  to  the  size  of  an  ordinary  bristle.  For  the  greater  part  of 
its  length  the  duct  is  straight,  but  beneath  the  bladder  it  becomes 
enlarged,  tortuous,  and  more  or  less  sacculated.  In  this  latter  position 
its  walls  are  thinner  and  its  capacity  greater  than  elsewhere ;  but  ap- 
proaching its  termination  it  again  becomes  narrower. 

1  Vasculum,  or  vas  aberrans ;  v.  a.  Halleri. 

2  Canalis,  or  ductus  deferens  ;  vibrator. 


THE   GENERATIVE   APPARATUS. 


473 


The  structure  of  the  vas  deferens  is  the  same  as  that  of  the  epididy- 
mis;  consisting  of  an  external  fibrous  coat,  an  unstriated  muscular 
layer,  and  a  lining  mucous  membrane.  The  latter  is  thrown  into  fine 
longitudinal  folds ;  and  in  the  terminal,  sacculated  portion  of  the  tube, 
exhibits  fine  reticular  folds. 

The  testicle  receives  blood  from  the  spermatic  artery.  The  spermatic 
duct  is  supplied  by  the  deferent  artery,1  a  long,  thread-like  vessel 
derived  from  the  superior  vesical  artery.  After  giving  branches  to  the 
epididymis,  the  remainder  of  the  spermatic  artery  penetrates  the  testis 
through  the  mediastinum,  and  ramifies  in  the  vascular  tunic.  The  sper- 
matic veins,  emerging  from  the  back  of  the  testicle  as  they  ascend  the 
spermatic  cord,  form  an  intricate  anastomosis,  named  the  pampin/iform 
plexus.2  The  lymphatics  of  the  testicle  are  numerous  and  large,  and 
communicate  with  the  lumbar  ganglia.  The  nerves  are  derived  from  the 
spermatic  plexus  of  the  sympathetic. 

THE  SEMINAL  YESICLES  AND  EJACULATORY  DUCTS. 


FIG.  299. 


The  Sem/inal  vesicles3  are  two  compressed,  ovoidal  bodies,  closely 
adhering  to  the  under  surface  of  the 
fundus  of  the  bladder.  They  are 
quite  near  each  other  behind  the 
prostate  gland,  but  diverge  poste- 
riorly so  as  to  include  a  triangular 
space.  They  are  separated  from 
the  rectum  only  by  the  thin  recto - 
vesical  fascia ;  and  to  their  innei1 
side  lies  the  terminal  sacculated 
portion  of  the  spermatic  ducts. 
They  vary  in  size,  but  usually  are 
about  two  inches  long  and  half  an 
inch  wide.  Their  posterior  ex- 
tremity is  obtuse ;  and  their  ante- 
rior extremity  narrows  into  a  short 
duct,  which  joins  with  the  corre- 
sponding spermatic  duct,  at  a  very 
acute  angle,  to  form  the  ejaculatory 
duct. 

The  seminal  vesicles  consist  each  of  a  coarse  tube  closed  at  the  pos- 
terior extremity,  and  convoluted   into  a  mass.     When  unraveled,  the 

1  A.  vasis  deferentis  Cooperi.  3  Vesiculae,  or  capsulae  seminales ;  v. 

2  Corpus  pampiniforme.  spermaticae  ;     conceptacula    seminaria  ; 

gonecystides. 


POSTERIOR  VIEW  OF  THE  FUNDUS  OF  THE  BLADDER 
1,  peritoneum  extending  as  far  down  as  the  trans- 
verse line;  2,  ureters;  3,  spermatic  ducts;  4,  semi- 
nal vesicle  of  the  left  side ;  5,  right  seminal  vesicle 
dissected  so  as  to  show  its  tubular  character ;  6, 
duct  of  the  seminal  vesicle,  joining  the  spermatic 
duct  to  form  7,  the  ejaculatory  duct ;  8,  prostate 
gland ;  9,  membranous  portion  of  the  urethra. 


474 


THE   GENERATIVE   APPARATUS. 


FIG.  300. 


tube  is  found  to  be  three  or  four  inches  long,  the  diameter  of  an  ordi- 
nary goose-quill,  and  provided  with  a  few  simple  and  branching  co3cal 
appendages.  In  structure,  they  are  like  the  sacculated  terminal  portion 
of  the  spermatic  ducts,  except  that  their  wall  is  thinner. 

The  Ejac'ulatory  ducts1  are  formed  by  the  conjunction,  on  each  side, 
of  the  corresponding  spermatic  duct  with  that  of  the  seminal  vesicle. 
They  are  nearly  an  inch  long,  and  converge  to  the  prostate  gland, 
through  which  they  pass  side  by  side  to  terminate  at  the  border  of  the 
orifice  of  the  utricle  communicating  with  the  urethra.  They  have 
thin  walls,  gradually  become  narrower  in  their  course,  and  end  each  in  a 
slit-like  aperture. 

The  seminal  vesicle  and  ejaculatory  ducts  receive  blood  through 
branches  of  the  inferior  vesical  and  middle  haemorrhoidal  arteries. 
Their  nerves  are  derived  from  the  hypogastric  plexus  of  the  sympa- 
thetics. 

The  testicles  secrete  the  spermatic  liquid,  which  accumulates  in  the 
sacculated  terminal  portions  of  the  spermatic  ducts,  and  in  the  sem- 
inal vesicles.  The  latter,  however,  not  only 
serve  as  reservoirs  to  the  spermatic  liquid, 
but  likewise  secrete  a  fluid  which  serves  to 
dilute  the  more  viscid  secretion  of  the  testi-. 
cles.  The  ejaculated  spermatic  liquid  or  se- 
men2 is  a  whitish,  viscid  matter,  mainly  con- 
sisting of  a  colorless  liquid  containing  im- 
mense numbers  of  minute  bodies  named  sperm- 
atozo'ids.3  These  are  the  essential  constituent 
of  the  spermatic  liquid  of  animals — that  upon 
which  its  fecundating  power  depends.  They 
vary  in  form  and  size  in  different  animals,  and 
are  endowed  with  inherent  power  of  movement. 
In  man  they  are  about  the  --An  of  an  inch  long, 

SPERMATOZOIDS.  1,  magnified  350  .    ,        .  .  _    .  °, ,         ..,          , 

diameters;  2,  magnified  800  diame-     and    COUSlSt    Of   an   OVOldal    head,  With   a.long, 

ters;  a,  viewed  on  the  narrower    filamentary  appendage  or  tail,  which  vibrates 

side;  b,  on  the  broader  side.  . ,,  .  ,.  mi  .  -, 

with  wonderful  rapidity.     The  spermatozoids 

are  not  properly  independent  animals,  as  was  once  generally  supposed, 
but  simply  particles  of  the  structure  of  an  animal ;  a  constituent  portion 
of  the  contents  of  the  spermatic  cells  of  the  testicles.  In  the  case  of 

1  Ductus,  or  canales  ejaculatorii ;  common  seminal  ducts. 

2  Sperma;  sperm;  seminal  fluid;  seed;  semen  virile,  masculinum,  or  genitale. 

3  Spermatozoa ;  spermatic  filaments. 


\ 


THE  GENERATIVE  APPARATUS.  475 

ciliated  epithelial  cells  we  have  more  complex  particles  of  an  animal 
structure,  also  endowed  with  movement,  and  although  ordinarily  fixed, 
when  artificially  detached,  they  move  in  liquids  in  the  same  manner  as 
the  spermatozoids.  The  quivering  of  a  detached  fragment  of  muscle  is 
no  indication  of  its  being  an  independent  animal ! 


THE  PENIS. 

The  Penis1  is  composed  of  three  columnar  bodies  invested  by  skin 
and  filled  with  a  peculiar,  vascular,  sponge-like  structure,  upon  the  dis- 
tention  or  emptying  of  which  the  erection  or  collapse  of  the  organ  de- 
pends. 

The  attachment  of  the  penis  to  the  pubic  arch  and  symphysis  is 
named  its  root ;  the  free  extremity  is  its  glans  or  head ;  and  the  inter- 
mediate portion  is  the  body.  The  surface  of  the  latter,  directed  forward 
in  a  collapsed  state  of  the  organ,  but  backward  in  its  erect  condition,  is 
named  the  dorsum  or  back. 

The  Glans2  is  a  blunt  cone  with  an  expanding  base,  named  the  corona,3 
beneath  which  is  the  constriction,  named  the  cervix  or  neck.4  The  sum- 
mit5 of  the  glans  presents  a  vertical  slit-like  orifice,6  which  is  the  termin- 
ation of  the  urethra. 

The  skin  of  the  penis  is  thin,  and  adheres  to  the  organ  by  a  loose 
superficial  fascia  allowing  much  freedom  of  movement.  At  the  free  ex- 
tremity of  the  penis  it  forms  a  loose  cup-like  fold,  named  the  pre'puce,7 
after  which  it  is  reflected  on  the  cervix  and  upon  the  glans.  To  the 
latter  it  firmly  adheres  ;  and  from  below  the  urinary  meatus  it  extends 
in  a  median  fold,  named  the  prepu/tial  fraenum.8 

In  front  of  the  pubis  the  skin  invests  a  thick  accumulation  of  fat,  and 
is  abundantly  provided  with  crisp  hairs,  projecting  from  among  whitish 
groups  of  sebaceous  glands.  On  the  body  of  the  penis  the  skin  is 
always  free  from  fat,  and  is  provided  with  scattered  crisp  hairs,  which 
diminish  and  finally  disappear  anteriorly.  It  also  presents  many  whitish 
groups  of  sebaceous  glands,  which  are  especially  congregated  about  the 
roots  of  the  hairs,  and  on  the  under  part  of  the  penis. 

1  Membrum  virile ;  phallus;  mentula;  4  Collum;  sulcus  retro-glandularis. 
priapus;  veretrum;  virga;  coles;  verpes;           5  Apex  glandis. 

nervus;  cauda;  the  yard;  the  male  or-  6  Meatus  urinarius;  orificium urethra?, 

gan,  etc.  T  Praeputium  ;  foreskin. 

2  Balanus  ;  caput  penis.  8  Frsenurn,  or  frsenulum  prseputii. 

3  Corona  glandis. 


476  THE  GENERATIVE  APPARATUS. 

At  the  free  border  of  the  prepuce,  the  skin,  as  it  folds  inwardly,  as- 
sumes more  the  character  of  a  mucous  membrane,  becoming  softer, 
thinner,  and  more  moist,  and  it  is  destitute  of  perspiratory  glands  and 
hairs.  At  the  cervix  and  corona,  it  is  abundantly  furnished  with  seba- 
ceous follicles,  named  the  prepu'tial  glands.1  The  secretion  of  these, 
together  with  the  desquamated  epidermal  cells  of  the  cervix,  constitute 
the  smegma,2  a  white  caseous  substance,  readily  decomposing,  and  emit- 
ting a  strong  odor.  Upon  the  glans,  the  skin  becomes  most  vascular 
and  sensitive,  and  is  devoid  of  glands. 

The  superficial  fascia  of  the  penis  is  continuous  with  that  of  the  ab- 
domen and  perineum,  and  with  the  dartos  of  the  scrotum,  and  is  always 
free  from  fat.  From  the  lower  part  of  the  linea  alba,  and  the  front  of 
the  pubes,  a  fibro-elastic  fasciculus,  named  the  suspensory  ligament,3 
descends  to  the  root  of  the  penis  and  becomes  continuous  with  its  super- 
ficial fascia. 

The  Cav'ernous  bodies4  are  two  long  fusiform  columns,  whose  poste- 
rior extremities,  named  crura,  spring  from  the  inner  border  of  the  rami 
of  the  ischia  and  pubes.  Converging,  the  crura  join  each  other  in  the 
median  line,  after  which  the  cavernous  bodies  lie  side  by  side,  intimately 
associated,  until  they  terminate  in  a  common  conical  extremity,  which  is 
capped  by  the  glans.  The  crura  have  a  firm  tendinous  attachment  to 
the  pubic  arch,  and  each  crus  is  somewhat  swollen5  before  it  conjoins 
with  the  other.  A  slight  groove  between  the  cavernous  bodies  on  the 
dorsum  of  the  penis  is  occupied  by  the  dorsal  blood-vessels,  and  a  deeper 
groove  below  accommodates  the  spongy  body. 

The  cavernous  bodies  have  a  strong  exterior  wall,  consisting  of  a 
dense,  tendon-like,  fibrous  membrane.  Where  they  conjoin,  the  latter 
forms  an  intervening  vertical  partition,  which  is  complete  and  is  thickest 
posteriorly ;  but  anteriorly  its  fasciculi  are  separated  by  clefts,  which 
give  the  partition  a  comb-like  arrangement ;  hence  the  name  of  pectini- 
form  septum.6  From  this  septum  bands  diverge  to  the  interior  surface 
of  the  cavernous  walls,  besides  which  other  bands  pass  in  all  directions 
through  the  interior  of  the  cavernous  bodies.  The  bands,  composed  of 
fibro-elastic  tissue,  are  named  trabec'ulae,  and  these,  together  with 
blood-vessels  occupying  their  intervals,  form  a  soft,  red,  spongy  sub- 
stance, the  erec'tile  tissue7  of  the  cavernous  bodies. 

1  Glandulae  prae put i ales ;  g.  odoriferae  4  Corpora  cavernosa ;    c.  nervosa ;    c. 
praeputii ;  g.  o.  Tysoni ;  g.  Tysonianae  ;  nerveo-spongiosa ;  corpus  carvernosum. 
g.  sebaceae  glandis ;  g.  coronse  penis.  5  Bulb  of  the  cavernous  body. 

2  Sebum  praeputiale.  6  Septum  pectiniforme ;  s.  penis. 

3  Ligamentum  suspensorium  penis.  7  Textus,  or  tela  erectilis. 


THE  GENERATIVE   APPARATUS. 


477 


FIG.  301. 


The  Spongy  body1  commences  in  front  of  the  triangular  ligament  of 
the  pubis,  below  the  crura  of  the  cavernous  bodies,  in  an  enlargement 
named  the  bulb,2  From  this  it  extends  along  the  groove  below  the 
cavernous  bodies,  cylindroid  in  form  but  slightly  narrowing,  and  at  the 
anterior  extremity  of  the  latter  ex- 
pands into  the  glans.  The  base  of 
the  bulb  is  divided  by  a  median 
groove,  and  is  in  contact  with  the 
triangular  ligament.  The  base  of 
the  glans  is  excavated,  and  fits 
upon  the  conical  termination  of 
the  cavernous  bodies. 

The  urethra  enters  the  spongy 
body  above  and  in  advance  of  the 
base  of  its  bulb,  and  then  traverses 
the  entire  length  of  the  former  to 
terminate  at  the  summit  of  the 
glans. 

The  spongy  body  is  provided  with  an  exterior  fibrous  wall  and  an  in- 
terior erectile  tissue,  like  the  cavernous  bodies  ;  but  the  former  is  much 
thinner  and  the  latter  more  delicate  than  in  these. 

FIG.  302. 


TRANSVERSE  SECTION  OF  THE  PENIS,  a,  cavernous 
bodies :  the  vertical  line  in  the  middle  is  the  pec- 
tiniform  septum ;  those  diverging  from  it  are  the 
trabeculae ;  the  intervening  spaces  are  occupied  by 
erectile  tissue ;  b,  spongy  body ;  c,  urethra. 


VERTICAL  SECTION  OF  THE  PENIS  AND  BLADDER.  1,  pubic  symphysis ;  2,  triangular  ligament ;  3,  abdom- 
inal muscles;  4,  crus  of  the  right  cavernous  body;  5,  pectiniform  septum ;  6,  glans;  7,  spongy  body ;  8,  its 
bulb;  9,  bladder;  10,  its  summit;  11,  its  fundus;  12,  its  neck;  13,  prostatic  portion  of  the  urethra;  14, 
membranous  portion;  15,  spongy  portion;  16,  navicular  fossa;  17,  prostate  gland;  18,  suburethral  gland; 
19,  right  seminal  vesicle;  20,  spermatic  duct;  21,  ejaculatory  duct;  22,  urachus;  23,  peritoneum;  24,  its 
recto-vesical  fold. 

The   cavernous   bodies   are   supplied  with   blood   by  the  cavernous 
arteries,  together  with  a  few  small  branches  from  the  dorsal  arteries  of 

1  Corpus  spongiosum ;  c.  s.  urethrae ;   c.  cavernosum  urethrae ;   substantia  spon- 
giosa  urethrae. 

2  Bulbus  urethrae. 


478  THE  GENERATIVE  APPARATUS. 

the  internal  pudics.  The  cavernous  arteries  enter  the  crura  of  the  cav- 
ernous bodies  and  advance  near  the  pectiniform  septum,  ramifying  in 
their  course.  The  spongy  body  is  mainly  supplied  by  the  bulbo- 
urethral  arteries,  which  penetrate  the  bulb.  The  arteries  of  both  the 
cavernous  and  spongy  bodies  terminate  finally  in  the  interspaces  of  the 
erectile  tissue. 

According  to  Miiller  and  other  excellent  authorities,  many  of  the  ar- 
terial branches,  especially  at  the  root  of  the  penis,  form  short  convolu- 
tions, the  hel'icine  arteries,  which  occupy  intervals  of  the  erectile  tissue 
and  become  distended  in  erection.  According  to  Kolliker,  the  extremi- 
ties of  the  helicine  arteries  terminate  in  much  finer  vessels,  which  subse- 
quently open  into  interspaces  of  the  erectile  tissue.  From  the  latter 
generally,  which  hold  the  position  of  ordinary  capillaries,  but  which  are 
lined  with  an  epithelium  like  that  of  the  larger  blood-vessels,  the  veins 
of  the  penis  may  be  said  to  originate.  Those  of  the  cavernous  bodies 
partly  pass  out  between  these  and  the  spongy  body,  and  wind  around  the 
sides  of  the  penis  to  join  the  dorsal  veins.  Short  ones  penetrate  the 
cavernous  walls  and  immediately  join  the  latter ;  but  most  of  the  cavern- 
ous veins  pass  from  the  crura  and  join  the  prostatic  plexus.  The  veins 
from  the  spongy  body  mainly  converge  from  the  base  of  the  glans  around 
the  cervix  to  form  the  commencement  of  the  dorsal  veins ;  a  few  join  the 
latter  in  their  course  from  the  sides  of  the  spongy  body ;  and  others 
pass  back  from  the  bulb  to  join  the  prostatic  plexus. 

The  lymphatics  of  the  penis  are  numerous;  those  from  beneath  the 
skin,  commencing  at  the  glans,  communicate  with  the  inguinal  glands ; 
and  those  from  the  interior  of  the  cavernous  and  spongy  bodies  pass 
beneath  the  pubic  arch  to  join  the  lymphatic  plexus  around  the  prostate 
gland  and  fundus  of  the  bladder.  The  nerves  of  the  penis  are  also 
numerous,  and  are  derived  from  the  pudics  and  the  hypogastric  plexus 
of  the  sympathetics. 

THE  URETHRA  OF  THE  MALE. 

The  TTre'thra,1  a  canal  common  to  the  emission  of  urine  and  of  semen, 
extends  from  the  neck  of  the  bladder  to  the  summit  of  the  glans  penis. 
It  is  from  seven  to  ten  inches  in  length,  and  comprises  three  divisions : 
the  prostatic,  membranous,  and  spongy  portions. 

The  Prostat'ic  portion  of  the  Ure'thra2  proceeds  from  the  neck  of 
the  bladder  through  the  upper  part  of  the  prostate  gland,  whence  its 

1  Meatus,  ductus,  or  canalis  urinarius;  fistula  urinaria;  iter  urinarium. 

2  Pars  prostatica  urethree. 


THE  GENERATIVE  APPARATUS. 


479 


FIG.  303. 


name.  It  is  barrel  shaped,  from  one  to  one  and  a  half  inches  in  length, 
and  is  not  only  the  widest,  but  the  most  dilatable  portion  of  the  canal. 
At  the  bottom  it  presents  a  longitudinal  ridge, 
named  the  ure'thral  crest,1  in  the  front  of 
which  is  a  small  pouch,  viewed  as  analogous 
with  the  uterus  of  the  female,  and  named  the 
"u'tricle.2  This  extends  between  the  urethral 
crest  and  prostate  gland,  a  depth  of  from  one- 
fourth  to  one-half  an  inch,  and  has  the  orifices 
of  the  ejaculatory  ducts  opening  into  it  on  each 
side  of  its  communication  with  the  urethra. 

The  Membranous  portion  of  the  ure'thra,3 
continuous  from  the  former,  passes  out  of  the 
pelvic  cavity,  traversing  the  triangular  liga- 
ment about  an  inch  beneath  the  symphysis  of 
the  pubes.  It  is  about  three-fourths  of  an  inch 
long,  and  extends  from  the  apex  of  the  pros- 
tate gland  to  the  spongy  body  of  the  penis, 
above  and  in  advance  of  the  base  of  the  bulb. 
It  is  cylindrical,  curved,  with  the  convexity 
downward,  and  is  the  least  dilatable  portion  of 
the  urethra.  Besides  its  lining  membrane,  it 
has  an  exterior  layer  of  unstriated  muscular 
fibres,  a  thin  layer  of  erectile  tissue  continuous 
with  that  of  the  spongy  body,  and  a  fibrous 
investment  continuous  with  the  triangular  liga- 
ment. 

The  Spongy  portion  of  the  ure'thra,4  the 
most  variable  in  its  length  and  direction,  in- 

.  °  latter  open;  d,  spongy  portion  of 

eludes  the  remainder  of  the  canal,  extending    the  urethra  within  the  bulb,  e;/, 
from  the  membranous  portion  through  the  in-    crura  of  the  cavernous  bodies,  </; 

h,  continuation  of  the  spongy  por- 

terior  of  the  spongy  body  of  the  penis  to  the    tion  of  the  urethra, 
summit  of  the  glans.     Within  the  bulb  it  is 

somewhat  dilated ;  then  very  gradually  diminishes  to  the  glans,  in  which 
it  forms  an  abrupt  expansion,  the  navic'ular  fossa,5  terminating  in  the 


PART  OF  THE  BLADDER  AND  PENIS, 
"WITH  THE  URETHRA  LAID  OPEN  FROM 
ABOVE.  1,  internal  surface  of  the 
bladder ;  2,  space  called  the  yesical 
triangle ;  3,  position  of  the  orifice 
of  the  ureter  on  each  side  ;  4,  vesi- 
cal  uvula;  5,  urethral  crest;  6,  po- 
sition of  the  utricle;  7, 8,  prostatic 
portion  of  the  urethra  on  each  side 
of  the  crest ;  9,  prostate  gland,  a, 
membranous  portion  of  the  ure- 
thra ;  b,  suburethral  glands ;  c,  po- 
sition at  which  the  ducts  of  the 


1  Cristaurethralis;  caputgallinaginis; 
verumontanum  ;  caruncula,  or  colliculus 
seminalis. 

2  Utriculus ;    u.  prostaticus ;    uterus 
masculinus :  sinus  pocularis,  or  prosta- 
tse  ;  vesicula,  or  vesica  prostatica;  cor- 
pusculum  Weberianum ;  organ  of  Weber. 


3  Pars  membranacea  urethrse  ;  isthmus 
urethras. 

4  Pars  spongiosa  urethras  ;  pars  caver- 
nosa  urethrse. 

5  Fossa  navicularis,    or   scaphoides ; 
navicula  ;  scaphula ;  fossa  of  Malpighi, 
or  Morgagni. 


480  THE  GENERATIVE  APPARATUS. 

external  ure'thral  orifice.1  This  is  a  vertical  aperture,  and  is  the  nar- 
rowest point  of  the  urethra ;  an  instrument,  under  ordinary  circumstances, 
being  capable  of  passing  the  entire  length  of  the  canal  if  readily  intro- 
duced at  the  urethral  orifice. 

In  the  collapsed  condition  of  the  penis  the  entire  urethra  forms  a  sig- 
moid  or  S-like  curvature,  but  in  the  erect  condition  of  the  organ  it  forms 
a  U-like  curvature.  It  is  lined  with  a  smooth  mucous  membrane,  the 
free  surfaces  of  which,  in  the  greater  part  of  the  urethra,  are  in  contact 
from  above  downward  and  wrinkled  longitudinally.  During  the  emission 
of  urine  the  canal  assumes  a  more  cylindrical  form  and  the  wrinkles  dis- 
appear. The  mucous  membrane  is  provided  with  a  columnar  epithelium, 
a  fibro-elastic  submucous  layer  with  unstriated  muscular  fibres,  and  nu- 
merous minute  racemose  glands.2  The  ducts3  of  the  latter  open  forward 
into  the  urethra,  and  the  mouths  of  many  of  them  are  sufficiently  large 
to  admit  a  good-sized  bristle;  an  especially  large  one4  at  the  upper  part 
of  the  navicular  fossa  will  admit  the  end  of  an  ordinary  surgical  probe. 

THE  PROSTATE  AND  SUBURETHRAL  GLANDS. 

The  Pros'tate  gland5  resembles  in  size  and  form  a  Spanish  chestnut, 
and  is  within  the  pelvic  cavity,  between  the  neck  of  the  bladder  and  the 
triangular  ligament  surrounding  the  first  portion  of  the  urethra.  It  is 
usually  from  one  to  one  and  a  half  inches  in  length  and  breadth,  and 
about  three-fourths  of  an  inch  in  thickness.  Its  apex  adheres  to  the 
triangular  ligament,  and  its  notched  base  encircles  the  neck  of  the  blad- 
der. Its  flat  or  slightly  concave  under  surface  rests  against  the  rectum, 
through  the  front  wall  of  which  it  may  readily  be  felt.  The  sides  of  the 
prostate  gland  are  prominently  convex ;  and  they  project  backward  to 
such  an  extent  as  to  lead  to  their  being  distinguished  as  the  lateral 
lobes.  These  are  united  beneath  the  neck  of  the  bladder  by  a  prominent 
isthmus,  named  the  middle  lobe,  which  corresponds  in  position  with  the 
vesical  uvula.  When  enlarged  from  disease,  to  which  it  is  liable,  this 
third  lobe  of  the  prostate  projects  into  the  neck  of  the  bladder  so  as  to 
impede  the  emission  of  urine. 

The  prostate  gland  is  invested  with  a  fibrous  membrane,  continuous  in 
front  with  the  triangular  ligament,  behind  with  the  recto-vesical  fascia, 
at  the  sides  and  above  with  the  lateral  and  anterior  ligaments  of  the 

1  Meatus  urinarius.  5  Prostata  ;  glandula  prostata  ;   pros- 

2  Glands  of  Littre ;  glandule  Littria-       tata    adenoides  ;     parastata  ;     adstans  ; 
nse  ;  urethral  glands.  testis   minor ;    corpus   glandulosum ;    c. 

3  Lacunae  or  sinuses  of  Morgagni.  adenoides  ;    assistentes   glanduloe  ;    ad- 
*  Lacuna  magna.  stites  glandulosi. 


THE  GENERATIVE  APPARATUS.  481 

bladder.  Its  structure  is  of  firm  consistence,  of  a  pale,  reddish-gray 
color,  and  consists  of  a  mass  of  fibre-muscular  tissue  with  imbedded 
racemose  glands.  The  muscular  fibres,  which  are  unstriated,  are  partly 
longitudinal ;  and  in  the  vicinity  of  the  urethra  are  circular,  and  become 
continuous  with  those  of  the  sphincter  of  the  bladder.  The  racemose 
glands  are  numerous,  and  open  into  the  urethra  at  the  sides  of  the 
urethral  crest. 

The  prostate  gland  is  probably  the  homologous  structure  with  the 
walls  of  the  uterus  and  vagina  of  the  female.  It  is  supplied  with  blood 
from  the  vesical,  haemorrhoidal,  and  pudic  arteries ;  and  its  veins  form  a 
remarkably  intricate  plexus  communicating  with  the  internal  iliac  veins. 

The  Subure'thral  glands1  (Cowper's)  are  two  compact,  rounded 
bodies  of  a  pinkish-yellow  color,  and  about  the  fourth  of  an  inch  in 
diameter,  situated  just  behind  the  bulb  of  the  spongy  body  and  below 
the  membranous  portion  of  the  urethra.  They  are  racemose  glands,  and 
empty  their  secretion,  by  a  long  duct,  into  the  urethra  within  the  bulb  of 
the  spongy  body. 

THE  FEMALE  ORGANS  OF  GENERATION. 

The  organs  of  generation  of  the  female  partly  occupy  the  interior  of 
the  pelvis  and  partly  the  exterior,  whence  their  division  into  the  internal 
and  external  organs.  The  former  consist  of  the  uterus,  ovaries,  Fallo- 
pian tubes,  and  vagina,  together  with  certain  accessories;  the  latter, 
comprised  under  the  general  name  of  vulva,  consist  of  the  mons  veneris, 
labia,  clitoris,  and  nymphae. 

THE  UTERUS. 

The  irterus,  or  womb,2  is  a  symmetrical,  hollow,  muscular  organ  pro- 
vided for  the  reception  of  the  ovum,  and  the  development  of  the  foetus. 
It  ordinarily  occupies  the  cavity  of  the  pelvis  between  the  rectum  and 
bladder,  but  during  pregnancy  greatly  increases  in  size,  and  rises  into 
the  cavity  of  the  abdomen. 

The  adult  unimpregnated,  or  virgin  uterus,  holds  an  oblique  position 
in  the  axis  of  the  pelvis,  with  its  upper  extremity  inclining  forward  and 
its  lower  extremity  directed  backward.  It  is  maintained  in  position  by 

1  Glandulee  Cowperi ;  g.  ante-prostatae ;  2  Utriculus  ;  matrix ;  hystera ;  inetra ; 

g.  prostatae  inferiores  ;    small  prostate      mater ;  mother ;  venter ;  alvus ;  gaster ; 
glands  ;  accessory  glands.  loci ;  conceptaculum. 

31 


482  THE  GENERATIVE  APPARATUS. 

its  attachment  to  the  vagina,  by  the  reflections  of  peritoneum  between  it, 
the  bladder  and  the  rectum,  by  the  round  ligaments,  but  more  especially 
by  the  broad  ligaments.  In  front  it  is  in  contact  with  the  bladder, 
behind  with  the  rectum,  and  above  with  the  small  intestine. 

FIG.  304. 


SKETCH  OF  THE  UTERUS  AND  ITS  APPENDAGES.  1,  uterus,  with  its  peritoneal  covering  partially  retained; 
'2,  its  fundus;  3,  its  neck,  with  the  fore  part  of  the  attachment  of  the  vagina  removed;  4,  mouth  of  the 
uterus;  5,  interior  of  the  vagina;  6,  broad  ligament,  removed  on  the  opposite  side;  7,  position  of  the  ovary 
behind  the  broad  ligament;  8,  round  ligament;  9,  oviduct  or  Fallopian  tube;  10,  its  fimbriated  extremity; 
11,  ovary;  12,  ovarian  ligament;  13,  process  connecting  the  fimbriated  extremity  with  the  ovary;  14,  cut 
border  of  the  broad  ligament. 

The  uterus  is  pyriform,  but  compressed  from  before  backward.  Its 
narrow  extremity  below  is  the  neck;1  its  upper  broad  extremity,  the 
fundus  ;2  and  the  intervening  portion  is  the  body.3  Its  length  is  about 
two  and  a  half  inches,  of  which  the  body  comprises  one  and  a  half  inches 
or  more,  and  approaches  two  inches  in  its  greatest  breadth,  and  one  inch 
in  thickness. 

The  body  of  the  uterus  is  less  convex  in  front  than  behind,  and  is  in- 
closed in  a  doubling  of  peritoneum,  which,  passing  off  at  the  sides,  pro- 
duces the  broad  ligaments.  The  fundus  is  convex,  and  at  the  sides  is 
continuous  with  the  Fallopian  tubes  and  the  round  ligaments.  The  neck 
is  cylindroid,  and  partly  projects  into  the  vagina,  with  which  it  is  con- 
tinuous. The  lower  end  of  the  neck  exhibits  a  transverse  elliptical  ori- 
fice, the  mouth  of  the  uterus,4  which  opens  into  the  vagina,  and  is 
bounded  by  a  pair  of  thick,  smooth  lips.  The  anterior  lip  is  the  longer, 
and  descends  more  deeply  into  the  vagina  than  the  posterior  lip.  This, 
however,  projects  more  into  the  vagina  in  consequence  of  the  walls  of 
the  latter  being  connected  higher  with  the  neck  of  the  uterus  behind 
than  in  front. 

The  cavity  of  the  uterus  is  a  narrow  space  included  by  thick  walls, 
which  come  into  contact  by  their  inner  surfaces  anteriorly  and  poste- 

'  Cervix.  2  Base.  3  Corpus. 

4  Os  uteri;  o.  u.  externum;  os  tincse  ;  orificium  vaginale. 


THE   GENERATIVE  APPARATUS. 


483 


FIG.  305. 


A.  SECTION  OF  THE  UTERUS  ANTERO-POSTERIORLY.   1,  back  part  of 
the  uterus ;  2,  vagina ;  3,  cavity  of  the  body ;  4,  cavity  of  the  neck . 

B.  SECTION  OF  THE  UTERUS  FEOM  SIDE  TO  SIDE.    1,  fundus;  2,  va- 
gina; 3,  cavity  of  the  body;  4,  cavity  of  the  neck. 


riorly.  The  cavity  of  the  body  from  side  to  side  is  triangular,,  but  in 
section  from  before  backward  appears  as  a  mere  slit.  The  sides  of  the 
triangular  cavity  are  con- 
vex inwardly,  and  the  an- 
gles are  prolonged — the 
two  upper  ones  to  com- 
municate with  the  Fallo- 
pian tubes,  the  lower  one 
to  form  the  internal 
mouth  of  the  uterus,1 
The  cavity  of  the  neck,2 
with  which  the  latter  com- 
municates, from  side  to 
side  is  longitudinally  oval, 
and  from  before  backward 
in  section  appears  as  a 
wide  fissure. 

The  walls  of  the  uterus  average  about  half  an  inch  in  thickness,  and 
give  to  the  organ  a  remarkably  firm  and  solid  consistence.  They  are 
mainly  muscular,  but  externally  are  provided  with  a  partial  investment 
of  peritoneum,  and  internally  are  lined  with  a  mucous  membrane.  In 
section  they  appear  of  a  pale  reddish  hue,  and  present  the  orifices  of 
numerous  vessels,  especially  near  the  lateral  borders  of  the  organ. 

The  muscular  portion  of  the  uterine  walls  is  formed  of  an  intricate 
arrangement  of  short,  fusiform,  unstriated  muscular  fibres,  associated 
with  connective  tissue  and  blood-vessels.  In  the  enlargement  of  the 
uterus  during  pregnancy,  the  muscular  fibres  undergo  a  remarkable 
development  in  length. 

The  peritoneum  invests  the  body  and  the  upper  portion  of  the  neck 
of  the  uterus,  and  intimately  adheres  to  the  muscular  structure  beneath, 
except  at  the  lateral  borders,  where  it  forms  the  broad  ligaments. 

The  mucous  membrane  of  the  cavity  of  the  body  is  thin,  soft,  smooth, 
and  of  a  pale-red  color.  It  intimately  adheres  to  the  subjacent  muscular 
structure  without  the  intervention  of  a  fibrous  layer,  and  is  continuous 
with  the  mucous  membrane  of  the  Fallopian  tubes,  and  that  of  the  neck 
of  the  uterus.  It  is  provided  with  a  ciliated  columnar  epithelium,  and 
numerous  tubular  glands,  the  orifices  of  which  give  to  the  membrane  a 
finely  punctated  appearance.  The  glands  are  generally  simple,  a  few 
being  divided  at  their  deeper  part,  where  they  are  somewhat  tortuous. 


1  Os  uteri  internum ;  ostium,  or  isthmus  uteri ;  orificium  uterinum. 

2  Canalis  cervicis. 


484  THE  GENERATIVE  APPARATUS 

In  the  cavity  of  the  neck  of  the  uterus,  the  mucous  membrane  is 
thicker,  less  soft,  and  paler  than  that  of  the  body.  It  is  thrown  into 
numerous  folds,1  for  the  most  part  divergent  from  a  median  fold  in  front 
and  behind,  and  including  between  them  many  smaller  folds.  The  mem- 
brane is  provided  with  a  squamous  epithelium,  and  numerous  minute, 
simple  follicular  glands,  which  secrete  a  tenacious  mucus.  These  glands 
sometimes  become  closed  and  distended  with  their  contents,  in  which 
condition  they  have  been  mistaken  for  ova.2 

The  arteries  of  the  uterus  on  each  side  are  branches  of  the  ovarian 
and  uterine  arteries,  and  are  remarkable  for  their  many  anastomoses  and 
tortuous  course.  The  veins  are  large,  and  form  an  intricate  plexus, 
from  which  branches  emanate  corresponding  with  the  uterine  arteries. 
The  lymphatics  are  likewise  numerous,  especially  in  the  pregnant  con- 
dition of  the  organ.  The  nerves  are  derived  from  the  ovarian  and  hypo- 
gastric  plexuses  of  the  sympathetic  system. 

LIGAMENTS  OF  THE  UTERUS. 

The  Broad  ligaments3  consist  of  the  doubling  of  peritoneum  which 
passes  from  each  side  of  the  uterus  to  the  sides  of  the  pelvis.  They 
contain  the  Fallopian  tube,  the  ovary,  parovarium,  round  ligament,  the 
uterine  blood-vessels,  lymphatics  and  nerves,  together  with  connective 
and  some  unstriated  muscular  tissue,  which  unite  the  two  layers  of  the 
broad  ligaments. 

The  Recto-uterine,  and  Vesico-uterine  folds4  of  peritoneum,  acting 
the  part  of  ligaments,  pass  respectively  between  the  sides  of  the  uterus, 
rectum,  and  bladder.  These  folds  contain  extensions  of  fibrous  tissue 
from  the  uterus  to  the  neighboring  parts,  which  have  likewise  been 
described  as  ligaments.5 

The  Round  ligament6  is  an  extension  of  the  structure  of  the  uterus, 
consisting  of  a  flattened  cord  of  unstriated  muscular  and  fibrous  tissue. 
It  commences  at  the  side  of  the  fundus  of  the  uterus,  a  little  below  and 
in  front  of  the  connection  of  the  Fallopian  tube,  and  proceeds  outwardly 
within  a  slight  fold  of  the  anterior  layer  of  the  broad  ligament,  to  the 

1  Arbor  vitse.  3  Ligamenta  lata ;  alae  vespertilionis ; 

2  Ovula  Nabothi ;  glandulae  Nabothi ;       retia  uteri. 

glands,  or  eggs  of  Naboth;   hydatides,  *  Anterior   and    posterior  ligaments; 

glandulae,  vesiculae,  or  bullae  rotundae  plicae  semilunares. 

cervicis  uteri ;  folliculi  rotundi  and  ob-  5  Utero-sacral  and  utero-vesical  liga- 

longi;    vesiculae   seminales   mulierum;  ments. 

corpuscula  globosa.  6  Ligamentum  rotundum. 


THE   GENERATIVE  APPARATUS.  485 

inguinal  canal.  Through  this  it  descends  and  fades  away  in  the  subcu- 
taneous tissue  of  the  pubis.  A  pouch  of  peritoneum1  occasionally 
accompanies  it  into  the  canal  in  young  persons,  which  is  usually  obliter- 
ated in  the  adult.  This  pouch  may  become  the  avenue  of  the  abnormal 
descent  of  the  ovary  into  the  labium,  or  it  may  be  the  seat  of  hernia. 

THE  OVAKIES. 

The  O'varies2  are  to  the  female  what  the  testicles  are  to  the  male : 
organs  for  the  production  of  the  germs  of  future  offspring.  They  are 
two  compressed  ovoid  bodies,  suspended  behind  the  broad  ligaments, 
inclosed  in  a  pouch  of  their  posterior  layer.  They  are  situated  nearly 
horizontally  from  half  an  inch  to  an  inch  or  more  from  the  uterus,  and  a 
little  below  the  Fallopian  tube. 

The  ovary  varies  in  dimensions  and  appearance  at  different  ages,  and 
in  different  individuals.  It  is  largest  in  the  virgin  between  the  period 
of  puberty  and  adult  age,  and  is  then  pearly  white,  smooth,  and  plump 
in  appearance.  From  the  period  of  puberty,  ova  periodically  escape 
through  ruptures  of  the  surface  of  the  ovary,  a  process  which  continues 
up  to  nearly  fifty  years  of  age.  The  effect  of  the  frequent  ruptures  and 
their  cicatrization  is  to  give  the  ovary  a  scarred  appearance,  which  in- 
creases with  the  advance  of  age  until  the  organ  is  finally  reduced  and 
shriveled  to  less  than  half  its  original  size. 

The  fully-developed  ovary,  unaffected  by  its  function,  measures  about 
an  inch  and  a  third  transversely,  three-fourths  of  an  inch  in  depth,  and 
about  five  lines  in  thickness.  Its  lower  border  and  outer  extremity 
nearly  form  a  semicircle  ;  its  inner  extremity  is  narrowed  and  connected 
with  the  ovarian  ligament ;  the  upper  border  is  straight,  and  is  the  part 
by  which  the  ovary  is  suspended  from  the  broad  ligament.  The  ante- 
rior and  posterior  surfaces  are  free,  and  the  latter  is  the  more  convex. 

The  ova'rian  ligament  is  a  fibrous  band  mingled  with  muscular  fibres, 
which  extends  from  the  narrow  end  of  the  ovary  to  the  side  of  the  uterus 
just  below  and  behind  the  connection  of  the  Fallopian  tube. 

Beneath  the  peritoneal  coat,  derived  from  the  posterior  layer  of  the 
broad  ligament,  the  ovary  is  provided  with  a  dense  fibrous  tunic,3  inti- 
mately associated  with  its  serous  investment  and  the  contents  of  the 
ovary.  At  the  upper  border4  of  the  latter  the  fibrous  tunic  is  perforated 
by  the  passage  of  the  ovarian  blood-vessels  and  nerves. 

The  contents  of  the  ovary  consist  of  a  reddish,  spongy,  fibrous  stroma,5 

1  Canal  of  Nuck.  3  Tunica  albuginea. 

2  Ovaria.     Sing:  ovarium  ;  testis  mu-  *  Hilus  ovarii. 
liebris,  or  femineus  ;  vesicarium.  5  Parenchyma. 


486 


THE  GENERATIVE  APPARATUS. 


TRANSVERSE  SECTION  OF  AN  OVARY, 


In  the 

interior,  two  old  corpora  lutea  are 
visible. 


abundantly  supplied  with  blood-vessels,  and  containing  numerous  closed 
vesicular  bodies  named  o'visacs.1  These  are 
especially  abundant  in  the  peripheral  portion 
of  the  stroma,  are  spherical,  and  vary  from  a 
microscopical  size  to  the  fourth  of  an  inch  in 
diameter.  The  walls  of  the  ovisacs  are  com- 
posed of  a  fibro-vascular  layer2  continuous  with 
the  stroma  of  the  ovary,  a  basement  membrane,3 
and  an  internal  layer  of  polyhedral  epithelial 
cells.4  The  interior  of  the  ovisacs  is  filled  with 
a  serous  liquid5  containing  some  granules,  nu- 

from  a  case  in  the  fifth  month  of    clei,  and  cells  apparently  detached  from  the 

pregnancy,      a,  b,  ovisacs;   c,  ova- UT_i; rm_  1,,-M-™    _  ^n  ^A«  *f  +!,«  ^_ 

rian  ligament ;  e,  stroma. 

sac  next  the  ovarian  surface,  presents  an  accu- 
mulation of  cells  named  the  germinal  emi- 
nence,6 within  which  is  enveloped  the  o'vum  or  egg. 

From  the  commencement  of  puberty,  the  ovisacs  in  succession  gradu- 
ally approach  the  surface  of  the  ovary,  and  become  enlarged  to  the  third 
of  an  inch  or  more  in  diameter.  The  envelopes  of  the  ovary  next  the 
ovisacs  gradually  thin  away,  and  the  latter  project  from  the  surface  of 
the  former.  Finally,  the  ovisacs  burst,  and  their  contents  escape  into 
the  abdominal  cavity,  and  are  thence  received 
into  the  pavilion  or  expanded  mouth  of  the 
Fallopian  tube.  The  rupture  or  dehiscence  of 
the  ovisacs  is  periodical,  and  is  attended  with 
a  general  afflux  of  blood  to  the  whole  gener- 
ative apparatus,  together  with  an  escape  of  a 
portion  of  that  liquid  from  distended  capillaries 
of  the  cavitv  of  the  uterus. 

HUMAN  OVUM,  highly  magnified.  J 


FIG.  307. 


a,  vitelline  membrane;  6,  yelk;  c, 
germinal  vesicle  containing  the 
germinal  spot. 


The  O'vum,7  discharged  from  the  ovisac, 
usually  retains  the  germinal  eminence8  and 
some  additional  shreds9  of  epithelium  attached.  These  are  subsequently 
rubbed  off,  and  the  isolated  ovum  appears  as  a  spheroidal  body  about 


1  Graffian  vesicles,  or  follicles ;    ovi- 
sacci;  folliculi  Graffiani,  or  ovarii;  vesi- 
cles of  De  Graaf. 

2  Vascular,    or  fibrous   coat ;    tunica 
fibrosa ;  theca  folliculi ;  ovicapsule  ;  tu- 
nic of  the  ovisac. 

3  Membrana  propria. 

4  Granular  layer ;    membrana  granu- 


5  Liquor  folliculi. 

6  Cumulus,  or  discus  proligerus ;  tuni- 
ca granulosa ;   germinal  disk. 

7  Ovulum;  ovule. 

8  Cumulus,   or  discus  proligerus;   tu- 
nica granulosa. 

9  Retinacula. 


THE  GENERATIVE  APPARATUS. 


48' 


FIG  308. 


the  tenth  of  a  line  in  diameter,  and  with  all  the  characters  of  an  or- 
ganic cell. 

The  exterior  of  the  ovum  consists  of  an  unusually  thick,  elastic,  struc- 
tureless wall  named  the  vit'elline  membrane,1  which,  when  viewed  be- 
neath the  microscope,  appears  as  a  broad,  transparent  zone2  encircling 
the  egg.  The  contents  of  the  ovum  consist  of  a  pale-yellowish  yelk,"' 
composed  of  a  viscid  liquid  mingled  with  a  multitude  of  granules. 
Within  the  yelk  is  a  large,  clear  nucleus,  called  the  germinal  vesicle,4 
containing  a  nucleolus  named  the  germinal  spot.5 

With  the  escape  of  the  contents  of  the  ovisac,  it  fills  with  blood. 
which  coagulates.  The  walls  of  the  ovisac 
subsequently  become  thickened,  corrugated, 
and  contracted  upon  the  blood  clot.  This 
loses  its  color,  and,  together  with  the  thickened 
walls  of  the  ovisac,  gradually  assumes  the  ap- 
pearance of  a  spheroidal,  corrugated,  yellowish 
body,  named  the  corpus  lu'teum.  The  latter 
afterwards  becomes  atrophied,  and  is  finally 
resolved  into  the  stroma  of  the  ovary.  The 
corpus  luteum,6  in  the  pregnant  condition,  ap- 
parently from  the  more  continued  afflux  of 
blood  to  the  part,  undergoes  a  greater  devel- 
opment, and  disappears  less  rapidly  than  the 
corpus  luteum7  produced  without  pregnancy. 

The  ovaries  are  supplied  by  the  ovarian  ar-       Two  CORPORA  LUTEA;  in  section, 

,  .   ,      „        ,  ',11  natural  size.    1,  eight  days  after 

tenes,  which  freely  anastomose  with  branches    conception.  2,at  the  fifth  month 
of  the  uterine  arteries.     The  veins  form  an  in- 

.    .  i  •    i     ji  • 

tncate  plexus  from  which  the  mam  vessels  pur- 
sue  the  course  of  the  ovarian  arteries.  The 
nerves  are  derived  from  the  ovarian  and  hypo- 
gastric  plexuses  of  the  sympathetic  system. 


of  pregnancy.  «,  fibrous  tunic  of  the 

ovary;  b,  stroma;  c,  thickened  and 

plic/ted  membrane  of  the  ovisac: 
d,  bioodciot;  e,  the  same,  later, 


THE  PAROVARIUM. 

The  Parova'rium8  is  situated  between  the  layers  of  the  broad  liga- 
ment, and  consists  of  a  series  of  whitish,  tortuous  tubes  diverging  from 


1  Membrana  vitelli-na;    oolemma  pel-       minativus  :      blasto-cardia ;      corculum 


lucidum;  cliorion. 

2  Zona  pellucida. 

3  Vitellus ;  yolk. 

4  Vesicula  germinativa,  or  prolifera  ; 
Purkinjean  vesicle  ;  germ  cell. 

5  Macula  germinativa;    nucleus  ger- 


germinis. 

6  True  corpus  luteum. 

7  False  corpus  luteum. 

8  Corpus  conicum ;   organ  of  Rosen 
muller ;   paroiirion ;    corpusculum  coni- 
cum Rosenmiilleri. 


488 


THE  GENERATIVE  APPARATUS. 


the  ovary  to  a  main  trunk  in  the  vicinity  of  the  Fallopian  tube.  It  is 
the  remains  of  an  organ  of  embryonic  life,  named  the  Wollfian  body, 
which  in  the  male  becomes  the  epididymis. 


FIG,  309. 


OVARY,  PAROVARITJM,  AND  FALLOPIAN  TUBE  OF  THE  LEFT  SIDE.  1.  broad  ligament;  2,  Fallopian  tube,  or 
oviduct;  3,  its  canal;  4,  its  fimbriated  extremity;  5,  mouth  of  the  latter,  or  pavilion;  6,  process  attached 
to  the  ovary  7;  8,  ovarian  ligament;  9,  orifice  from  which  an  ovum  recently  escaped;  10,  a  cicatrix  ; 
11,  parovarium ;  12,  remains  of  the  duct  of  Miiller.  From  a  virgin  of  about  eighteen  years  of  age. 

THE  FALLOPIAN  TUBES,  OR  OVIDUCTS. 

The  Fallo'pian  tube,  or  O'viduct,1  intended  to  convey  the  ovum  from 
the  ovary  to  the  uterus,  is  inclosed  in  the  upper  border  of  the  broad 
ligament.  It  is  a  trumpet-shaped  tube  of  about  four  inches  in  length. 
Commencing  above  and  externally  to  the  ovary,  it  gradually  narrows 
and  pursues  a  curvilinear  and  slightly  undulating  course  to  the  side  of 
the  fundus  of  the  uterus,  with  which  it  is  connected.  The  outer  ex- 
tremity is  free,  expanded,  and  opens  into  the  abdominal  cavity ;  and  its 
margin  is  fringed  with  a  number  of  irregular  processes,2  whence  it  is 
named  the  fim'briated  extremity.3  One4  of  the  longest  of  the  processes, 
with  fringed  edges  and  doubled  so  as  to  include  a  furrow,  extends  along 
the  border  of  the  broad  ligament  to  become  attached  to  the  outer  ex- 
tremity of  the  ovary.  The  expanded,  funnel-shaped  orifice  or  pavilion5 


1  Tuba  Fallopianse,  uteri,  or  caeca ; 
oviductus  muliebris ;  vas  spermaticus, 
ejaculans,  or  deferens  mulieris  ;  meatus 
seminalis  ;  m.  seminarius  uteri ;  ductus 
varicosus  uteri ;  processuslateralis  uteri ; 
vector  canal ;  uterine  canal. 


2  Fimbriae  ;  lacinioe  ;  vexillge  ;  digita- 
tiones. 

3  Morsus  diaboli ;  foliaceum  ornamen- 
tum. 

4  Tubo-ovarian  ligament,  or  fringes. 

5  Infundibulum ;   ostium   abdominale  ; 
corolla  infundibuliformis. 


THE  GENERATIVE  APPARATUS.  489 

of  the  fimbriated  extremity  narrows  into  the  canal  of  the  tube,  which  at 
its  communication1  with  the  cavity  of  the  uterus  is  so  small  as  hardly  to 
permit  the  passage  of  a  fine  bristle.  The  lining  membrane  of  the  canal 
is  longitudinally  plaited  or  provided  with  narrow  folds,  which  extend 
from  the  uterine  orifice  of  the  tube  to  the  fringed  processes  of  its  fim- 
briated extremity. 

In  structure  the  oviducts,  besides  their  peritoneal  investment,  have  a 
fibro-muscular  coat  and  a  lining  mucous  membrane.  The  peritoneal  or 
serous  tunic  formed  by  the  upper  border  of  the  broad  ligament  is  loosely 
attached  to  the  tube.  The  middle  coat  is  the  thickest  and  strongest, 
and  is  an  extension  of  the  structure  of  the  uterine  walls,  consisting  of 
fibrous  tissue  associated  with  unstriated  muscular  fibres.  The  lining 
mucous  membrane  is  soft,  pinkish  white,  and  furnished  with  a  ciliated 
columnar  epithelium. 

The  oviducts  are  supplied  with  branches  of  the  uterine  arteries.  Their 
veins  pursue  the  same  course  as  the  latter.  The  nerves  are  derived  from 
the  same  source  as  those  of  the  uterus  and  ovaries. 

Near  the  fimbriated  extremity  of  the  oviduct  there  usually  exists  an 
appendage,  consisting  of  a  small  sac  attached  by  a  long  pedicle.  This 
has  generally  been  looked  upon  as  a  hydatid,  but  recent  researches 
prove  it  to  be  the  remains  of  an  organ  of  the  embryo,  which  has  been 
named  the  duct  of  Miiller, 

THE  YAGINA. 

The  Vagi'na2  is  a  cylindroid  canal  extending  from  the  vulva  to  the 
uterus,  the  neck  of  which  projects  into  it.  Behind  it  is  in  relation  with 
the  bottom  of  the  recto-uterine  pouch  of  the  peritoneum,  and  below  this 
adheres  by  loose  connective  tissue  to  the  rectum.  In  front  it  adheres  to 
the  base  of  the  bladder  and  urethra,  and  at  the  sides  is  in  relation  with 
the  bottom  of  the  broad  ligaments,  pelvic  fascia,  and  anal  elevator  mus- 
cles. It  curves  upward  and  backward  in  the  direction  of  the  axis  of  the 
pelvis,  is  attached  to  the  neck  of  the  uterus  higher  posteriorly  than  an- 
teriorly, and  in  consequence  has  a  greater  length  behind  than  in  front. 

The  vagina  is  most  capacious  at  the  middle,  where  its  transverse 
diameter  is  greatest ;  and  it  slightly  narrows  toward  the  extremities. 
Ordinarily  its  anterior  and  posterior  walls  are  in  contact,  and  it  varies  in 
size  according  to  circumstances,  being  capable  of  much  enlargement.  In 
the  virgin  adult  it  measures  about  four  inches  in  length  by  an  inch 

1  Ostium  uterinum ;  internal  or  uterine  orifice. 

2  Vagina  uteri,  muliebris,  or  penis ;  sinus  muliebris,  pudoris,  or  pudendi ;  vulvo- 
uterine  canal. 


490  THE  GENERATIVE  APPARATUS. 

and  a  quarter  in  its  breadth.  After  frequent  intercourse  or  child-birth 
these  dimensions  are  much  exceeded. 

The  lower  orifice  or  entrance  of  the  vagina  is  constricted  in  the  virgin 
state  by  a  fold  of  the  lining  membrane,  named  the  hymen,1  This  usually 
appears  in  the  adult  as  a  crescentic  process  at  the  posterior  part  of  the 
entrance  of  the  vagina,  including  an  antero-posteriorly  elliptical  orifice. 
The  younger  the  individual,  the  more  does  this  process  approach  the 
form  of  a  complete  circular  zone,  which  is  the  ordinary  condition  of  the 
hymen  in  the  infant.  Sometimes  this  zone-like  form  is  retained  to  adult 
age ;  and  not  unfrequently  it  presents  a  puckered  appearance  toward  the 
central  aperture.  Commonly  the  hymen  is  obliterated  by  intercourse, 
child-birth,  or  other  means ;  and  if  its  free  edges  are  thin,  in  the  process 
of  dilatation,  these  may  be  torn.  As  an  abnormal  condition,  the  hymen 
is  occasionally  imperforate ;  and  in  rare  instances  it  is  so  strong  that 
impregnation  may  occur  without  its  being  destroyed.  Its  existence  is 
no  evidence  of  virginity,  nor  its  absence  any  to  the  contrary ! 

The  upper  extremity2  of  the  vagina  is  circular,  and  is  reflected 
smoothly  around  the  neck  of  the  uterus,  which  projects  into  it  as  a  short 
blunt  cone. 

The  internal  surface  of  the  vagina  on  its  anterior  and  posterior  wall 
is  roughened  with  numerous  transverse  folds3  passing  off  from  a  slight 
median  ridge,4  and  arranged  with  a  certain  degree  of  regularity.  The 
folds  are  often  interrupted  or  broken  into  wart-like  eminences ;  and  they 
are  remarkable  for  their  rigidity  in  comparison  with  similar  processes  of 
other  mucous  membranes.  They  are  most  numerous  near  the  entrance 
of  the  vagina,  where  some  of  them  are  named  the  myr'tiform  carbuncles,5 
though  these  are  usually  looked  upon  as  the  remains  of  the  hymen. 
From  repeated  child-birth  the  folds  of  the  posterior  wall  of  the  vagina 
become  completely  obliterated:  those  of  the  anterior  wall  partially. 
Frequent  intercourse  to  a  less  extent  produces  the  same  result. 

The  walls  of  the  vagina  average  about  one  line  in  thickness,  and  are 
composed  of  three  coats.  The  outer  coat,  adherent  to  the  contiguous 
organs,  consists  of  fibro-elastic  tissue.  The  middle  coat  consists  of 


1  Valvula,  or  membranula  lunata  va-  2  Fundus  ;  fornix. 

ginse ;  claustrum,  custodia,  columna,  flos,  3  Rugae. 

sigillum,  or  zona  virgintatis ;    circulus  4  Columna  rugarum ;    column  of  the 

membranosus ;    interceptum   virginale ;  vagina. 

cento,   or  flos  virginalis ;    argumentum  5   Carunculaa    myrtiformes ;    c.  vagi- 

integritatis  ;  zona,  or  munimentum  cas-  nales ;  glandulae  myrtiformes. 
titatis;    panniculus   hymenaeus,  or  vir- 
ginalis; Virginia;  virginal  membrane. 


THE  GENERATIVE  APPARATUS. 


491 


unstriated  muscular  fibres,  associated  with  fibro-elastic  tissue  and  blood- 
vessels, and  is  continuous  with  the  corresponding  structure  of  the  uterus. 
The  inner  coat  is  a  mucous  membrane  provided  with  a  multitude  of 
minute  conical  papillae,  imbedded  beneath  a  squamous  epithelium. 

The  vagina  is  supplied  with  arteries  from  the  vaginal,  uterine,  vesical, 
and  internal  pudics.  The  veins  on  each  side  form  an  intricate  plexus, 
from  which  vessels  proceed  in  the  course  of  the  arteries.  The  nerves 
are  derived  from  the  hypogastric  plexus  of  the  sympathetic  system,  the 
fourth  and  fifth  sacral,  and  the  internal  pudic  nerves. 

FIG.  310. 


SECTION  OF  FEMALE  PELVIS,  FROM  BEFORE  BACKWARD.  1,  sacrum ;  2,  coccyx ;  3,  pubic  symphysis ;  4,  rec- 
tum; 5,  one  of  its  valvular  folds ;  6,  anus;  7,  uterus;  8,  vagina;  9,  right  labium;  10,  right  nympha;  11, 
clitoris,  attached  by  the  suspensory  ligament  to  the  front  of  the  pubic  symphysis;  12,  glans ;  13,  prepuce  ; 
14,  urethra ;  15,  entrance  of  the  vagina ;  16,  bladder. 


THE  VULYA. 

As  previously  mentioned,  the  external  organs  of  generation  of  the 
female  are  comprised  under  the  general  name  of  vulva,1  and  consist  of 
the  mons  veneris,  labia,  clitoris,  and  nymphae. 

The  Mons  ven'eris2  is  the  prominence  of  skin  over  the  position  of  the 

1  Pudendum  ;  p.  muliebre ;  female  organs,  or  parts. 

2  Monticulus  veneris ;  supra-pubic  eminence. 


492 


THE  GENERATIVE  APPARATUS. 


pubic  symphysis,  to  which  it  is  attached  by  areolar  tissue  containing  an 
abundance  of  adipose  tissue.  Its  surface  is  provided  with  crisp  hairs 
and  large  sebaceous  glands. 

The  Labia1  are  two  parallel,  rounded  prominences  of  the  integument 
bounding  the  vertical  fissure  of  the  vulva,2  and  united  above  and 
below;  the  points  of  union  being  named  the  com/missures.3  They  are 
composed  of  a  quantity  of  areolar  and  adipose  tissue  covered  externally 
with  common  skin  and  internally  with  the  commencement  of  the  genito- 
urinary mucous  membrane.  Their  surface  is  supplied  with  many  seba- 
ceous glands,  and  the  external  skin  is  furnished  with  scattered  crisp  hairs. 
The  posterior  commissure  is  about  an  inch  from  the  anus ;  the  inter- 
vening space,  marked  by  a  median  raphe',  being  the  perine'um.  Just  within 

the  posterior  commissure,  and  sep- 
arated from  it  by  a  shallow  de- 
pression,4 is  an  inconspicuous  trans- 
verse fold,  named  by  midwives  the 
fourchette'.5  It  is  usually  obliter- 
ated or  torn  in  child-birth. 

The  labia  represent  the  scrotum 
of  the  male,  which  is  also  divided 
in  the  embryo.  The  raphe  of  the 
scrotum  indicates  the  line  of  con- 
fluence of  the  two  halves,  which  as 
the  labia,  remain  permanently  sep- 
arated in  the  female. 


FIG.  311. 


EXTERNAL  ORGANS  OF  GENERATION.*  1,  right 
pubis;  2,  tuberosity  of  the  ischium;  3,  symphysis 
of  the  pubes;  4,  left  half  of  the  mons  veneris;  5, 
left  labium;  6,  clitoris;  7,  cms  of  the  right  cav- 
ernous body;  8,  suspensory  ligament;  9,  dorsal 
vein;  10,  glans;  11,  pedicle  of  the  right  half  of 
the  spongy  body;  12,  right  semi-bulb;  13,  left 
nympha,  terminating  above  in  the  prepuce;  14, 
urethral  orifice  at  the  base  of  the  vestibule;  15, 
vagina;  16,  right  suburethral  gland. 


The  Clit'oris6  is  an  organ  cor- 
responding with  the  male  penis, 
which  it  resembles  in  general  form, 
structure,  and  connections.  It  is 
situated  at  the  upper  part  of  the 
fissure  of  the  vulva,  concealed  by 
the  labia.  When  these  are  sep- 
arated, it  is  seen  through  the  mucous  membrane  as  a  slight  vertical 


1  Labia    pudendi ;    1.  majora;    1.  ex- 
terna. 

2  Fissura,  or  f.  magna  vulvse ;  rima,  or 
r.  magna  vulvse ;  sinus  vulvae  ;  introitus  ; 
scapha. 

8  Commissurse  vulvse ;  c.  labiorum. 


4  Fossa  navicularis. 

6  Fraenulum,  or  froenum  pudendi ;  fur- 
cula  labiorum. 

6  Penis  muliebris,  or  femineus;  men- 
tula  muliebris ;  membrum  muliebre  ;  su- 
perlabia. 


THE  GENERATIVE  APPARATUS.  493 

prominence  terminating  below  in  the  glans.  It  is  about  two  inches  in 
length,  and  consists  of  a  pair  of  cavernous  bodies  and  a  bipartite  spongy 
body  ending  in  a  glans. 

The  Cav'ernous  bodies1  have  the  same  constitution,  attachment,  and 
relation  with  each  other  as  their  representatives  in  the  penis.  From  their 
ascending  crura,  which  constitute  about  half  their  length,  they  bend  ab- 
ruptly downward,  and,  lying  parallel  together,  form  the  body  of  the 
clitoris.  The  crura  and  body  are  thus  arranged  so  as  to  resemble  a 
tripod ;  and  from  the  bend  of  the  organ  a  strong  fibro-elastic  suspensory 
ligament2  ascends  to  be  attached  to  the  pubic  symphysis. 

The  Glans,3  constituted  like  that  of  the  penis,  is  a  small,  conical 
eminence  capping  the  lower  extremity  of  the  cavernous  bodies,  and  situ- 
ated about  an  inch  beneath  the  anterior  commissure.  It  is  imperforate 
in  consequence  of  the  divided  condition  of  the  spongy  body,  and  is  sur- 
rounded by  a  pre'puce4  continuous  at  the  sides  with  the  nymphae. 

The  Spongy  body5  extends  from  the  glans  as  a  narrow,  intermediate 
portion  or  pedicle,  along  each  side  of  the  under  part  of  the  body  of  the 
clitoris,  and  expands  in  the  semi-bulbs.  The  intermediate  portions6 
consist  of  a  plexus  of  veins  communicating  with  the  erectile  tissue  of 
the  glans  and  cavernous  bodies  enveloped  in  a  thin,  fibrous  membrane. 
The  semi-bulbs7  are  situated  beneath  the  vestibule,  and  embrace  the  ure- 
thral  and  vaginal  orifices.  They  are  about  the  size  and  form  of  a  large 
almond  kernel,  and  consist  of  an  erectile  tissue  continuous  with  the 
plexus  of  veins  of  the  pedicles,  and  invested  with  a  thin  fibro-elastic 
membrane. 

The  arteries,  veins,  and  nerves  of  the  clitoris  correspond  with  those  of 
the  penis. 

The  Nymphae8  are  two  crest-like  folds  of  mucous  membrane  diverging 
from  the  prepuce  of  the  clitoris  downward  and  outward  upon  the  inner 
border  of  the  labia.  Together  with  the  prepuce  and  the  mucous  mem- 
brane enveloping  the  clitoris,  they  correspond  with  the  integument  of 
the  penis.  The  raphe  of  the  latter  represents  the  separation  of  the 
nymphae. 


1  Corpora  cavernosa  clitoridis.  crura  clitoridis  interim;  erectile  tissue 

2  Ligamentum  suspensorum  clitoridis.  of  the  vestibule,  or  vagina. 

3  Glans  clitoridis.  8  Labia  minora;  1.  pudendi  minora; 
*  Praeputium  clitoridis.  1.  interna ;    cristae   clitoridis ;    alse   mi- 

5  Corpus  spongiosum  clitcridis.  nores  clitoridis ;    colliculi  vaginse  ;  car- 

6  Pars  intermedia  of  Kobelt.  unculse  cuticulares. 

7  Bulbi  vestibuli ;   plexus  retiformes; 


494  THE  GENERATIVE  APPARATUS. 

Between  the  nymphae  is  the  triangular  space  named  the  vestibule.1  It 
is  covered  by  mucous  membrane  continuous  with  the  inner  surface  of  the 
nymphae.  At  the  middle  of  its  base,  about  an  inch  below  the  glans,  is 
situated  the  urethral  orifice,  which  has  an  elevated  border,  so  that  to  the 
touch  it  appears  like  a  papillary  eminence. 

Just  below  the  vestibule  and  the  urethral  orifice  is  the  entrance  of  the 
vagina,  which  may  be  narrowed  by  the  presence  of  the  hymen  to  a  small 
aperture;  or,  if  this  is  obliterated,  it  appears  as  an  antero-posteriorly 
elliptical  orifice  an  inch  and  a  half  or  more  in  diameter. 

The  mucous  membrane,  traced  inwardly  from  the  labia,  covers  the  cli- 
toris, forms  the  nymphae  and  prepuce,  invests  the  vestibule,  and  is  then 
continuous  with  that  of  the  vagina  and  urethra.  It  is  smooth,  and  pink 
in  color,  and  is  furnished  with  a  squamous  epithelium  and  many  seba- 
ceous glands.2  Small  racemose  glands,  secreting  mucus,  also  open  on 
the  mucous  membrane  of  the  vestibule  and  around  the  urethral  and  vag- 
inal orifices. 

The  Subure'thral  glands  (Bartholine's)3  are  two  spheroidal  racemose 
glands,  about  a  third  of  an  inch  in  diameter  and  of  a  yellowish-pink 
hue,  situated  just  behind  the  lower  part  of  the  semi-bulbs  of  the  spongy 
body.  Their  duct  is  about  three-fourths  of  an  inch  long,  and  opens 
between  the  nymphae  and  the  vaginal  orifice.  They  appear  to  secrete 
mucus,  and  in  advanced  age  become  atrophied. 

The  blood-vessels  and  nerves  of  the  vulva  correspond  closely  with 
those  of  the  penis  and  scrotum. 

THE  CAVITY  OF  THE  PELVIS. 

The  Cavity  of  the  pelvis4  is  a  short,  wide,  and  curved  canal,  the  con- 
cavity of  which  is  directed  forward  and  downward.  Its  posterior  wall 
corresponds  in  length  with  the  curve  of  the  sacrum  and  coccyx ;  its  an- 
terior wall  with  the  pubic  symphysis.  It  is  longer,  narrower,  and  per- 
haps generally  more  curved  in  the  male  than  the  female.  The  entrance 
or  superior  strait  of  the  pelvis  is  cordiform,  the  notch  of  this  outline 
corresponding  with  the  promontory  of  the  sacrum.  The  exit  or  inferior 
strait  is  likewise  cordiform,  the  notch  being  produced  by  the  coccyx, 
and  it  is  narrower  than  the  superior  strait. 


1  Vestibulum ;  v.  vaginae  :  attrium  va-  of   the  female ;    glands   of   Duverney  : 
ginae  ;  ambitus  genitalis  muliebris.  glands  of  Mery ;  vulvo-vaginal  glands ; 

2  Glandulae  odoriferae  ;  g.  o.  Tysoni.  prostata  muliebris. 

3  Glandulse  Cowperi :  Cowper's  glands  4  True  pelvis. 


THE  GENERATIVE  APPARATUS. 


495 


In  the  male  the  cavity  of  the  pelvis  is  occupied  posteriorly  by  the 
rectum,  in  front  by  the  bladder,  and  between  these  is  the  recto-vesical 
pouch  of  the  peritoneum.  Beneath  the  bladder  are  the  seminal  vesicles, 
and  in  front  of  them,  surrounding  the  commencement  of  the  urethra,  is 
the  prostate  gland.  In  the  female  pelvis,  between  the  rectum  and  blad- 
der are  the  uterus  and  vagina,  together  with  the  broad  ligaments,  Fal- 
lopian tubes,  and  ovaries.  Between  the  rectum,  uterus,  and  bladder  are 
the  recto-  and  vesico-uterine  pouches  of  peritoneum. 

FIG.  312. 


SIDE  VIEW  OF  THE  MALE  PELVIS  A*o>  ITS  CONTENTS.  1,  the  right  pubis  sawed  through ;  2,  sacrum ;  3,  blad- 
der; 4,  its  summit;  5,  its  fundus;  6,  right  ureter;  7,  neck  of  the  bladder;  8,  attachment  of  the  pelvic 
fascia;  9,  prostate  gland;  10,  membranous  portion  of  the  urethra;  11,  triangular  ligament;  12,  subure- 
thral  gland  between  the  two  layers  of  the  latter;  13,  14.  spongy  body;  15,  right  cavernous  body;  16,  sig- 
moid  flexure  of  colon;  17,  recto-vesical  fold  of  peritoneum;  18,  rectum,  with  its  muscular  coat  seen; 
19,  right  seminal  vesicle ;  20,  spermatic  duct;  21,  pelvic  fascia  descending  to  the  rectum ;  22,  anal  elevator 
muscle;  23,  anal  sphincter;  24,  union  of  the  superficial  perineal  fascia  with  the  triangular  ligament  or 
deep  fascia;  25,  peritoneum  passing  from  the  summit  of  the  bladder  to  the  anti-rior  abdominal  wall. 

When  the  viscera  of  the  pelvis  above  mentioned  are  emptied,  a  por- 
tion of  the  small  intestine  descends  into  the  peritoneal  pouches  between 
them. 

The  sides  of  the  cavity  of  the  pelvis  are  occupied  by  the  pyriform, 
internal  obturator,  and  anal  elevator  muscles,  the  internal  iliac  blood- 
vessels and  lymphatics,  and  the  sacral  plexus  of  nerves. 


496 


THE   GENERATIVE   APPARATUS. 


THE  PERINEUM. 


FIG.  313. 


In  its  most  restricted  sense,  the  term  perme'um1  is  applied  to  the 

space  between  the  anus 
and  scrotum  in  the  male  ; 
between  the  anus  and  vul- 
va in  the  female.  In  a 
broader  view  of  the  anat- 
omy of  the  perineum,  it 
is  usual  to  describe  all 
the  soft  parts  at  the  out- 
let of  the  pelvis,  so  that 
in  this  relationship  the 
boundaries  of  the  perine- 
um are  the  arch  of  the 
pubes,  tuberosities  of  the 
ischia,  the  sacro  -  sciatic 
ligaments,  and  the  coc- 
cyx. 

The  skin  of  the  peri- 
neum is  thin,  dark  color- 
ed, abundantly  supplied 
with  sebaceous  and  per- 
spiratory glands,  and  is 
marked  in  the  middle  by 


VIEW  OF  THE  PERINEUM;  the  superficial  fascia  removed  from  the 
left  side  of  the  figure,  a,  transverse  perineal  muscle  proceeding 
from  the  tuberosity  of  the  ischium  to  the  perineal  centre;  6, 
greater  sacro-sciatic  ligament;  c,  anal  sphincter;  d,  anal  elevator; 
e,  ischio- cavernous  muscle;  /,  bulbo-urethi al  muscle  inclosing  the 
bulb  of  the  spongy  body.  1,  2,  internal  pudic  artery;  3,  inferior 
hsemorrhoidal  artery ;  4,  5,  6,  7,  superficial  perineal  branches ;  8, 
bulbo-urethral  artery ;  9,  cavernous  artery ;  10,  dorsal  artery  of 
the  penis. 


a    slightly  elevated 
called  the  raphe.2 


line 


THE  PELYIC  AND  PERINEAL  FASCIA. 

The  Pelvic  fascia3  is  attached  to  the  brim  of  the  pelvis,  and  is  there 
continuous  with  the  transverse  and  iliac  fasciae.  Posteriorly  it  descends 
upon  the  sacrum  and  pyriform  muscles  of  the  two  sides,  giving  them 
an  investment.  It  is  also  continuous  with  the  fibrous  sheaths  of  the  in- 
ternal iliac  vessels  and  sacral  plexuses  of  nerves.  Behind  the  pubes  it 
descends  and  attaches  itself  by  two  short,  narrow  processes4  to  the  sides 


1  Perinaeum ;    interfoemineum ;    inter- 
foramineum ;    regio   perinaei ;    foemen ; 
perin ;    mesomerion ;    mesocelon :   gres- 
sura;    amphiplex ;     plichos ;    cochone; 
tauros;  anterior  and  posterior  perineum. 

2  Tramis. 


3  Fascia  pelvis  ;  f.  hypogastrica. 

4  The  anterior  and  lateral  true  liga- 
ment of  the  bladder;  ligamentum  pubo- 
prostaticum  medium  et  laterale,  in  the 
male  ;  1.  pubo-vesicale  medium  et  later- 
ale,  in  the  female. 


THE   GENERATIVE   APPARATUS.  497 

of  the  prostate  gland  and  neck  of  the  bladder.  At  the  sides  of  the 
pelvis  it  descends  on  the  obturator  muscle,  and  forms  a  narrow  tendin- 
ous arch,1  which  curves  from  the  pubis  downward  and  backward  to  the 
spine  of  the  ischium.  From  the  tendinous  arch  emanate  the  recto-vesi- 
cal  and  ischio-rectal  fasciae,  and  between  these  originates  the  anal  ele- 
vator muscle. 

The  recto-vesical  fascia2  is  an  extension  of  the  pelvic  fascia  descend- 
ing on  the  inner  surface  of  the  anal  elevator  muscle  to  the  prostate 
gland,  neck  and  fundus  of  the  bladder,  and  side  of  the  rectum  in  the 
male;  to  the  bladder,  vagina,  and  rectum  in  the  female.  From  the 
point  of  contact  of  the  recto-vesical  fascia  with  the  organs  just  named 
it  becomes  continuous  with  their  fibrous  investments. 

The  ischio-rectal  fascia  lines  the  corresponding  space  throughout. 
Starting  from  the  tendinous  arch  of  the  pelvic  fascia,  one  lamina  invests 
the  outer  surface  of  the  anal  elevator,  and  becomes  continuous  with  the 
bottom  of  the  deep  perineal  fascia  and  the  thin  connective  tissue  of  the 
anal  sphincter  ;  another  lamina3  descends  on  the  lower  part  of  the  inter- 
nal obturator  muscle,  and  attaches  itself  to  the  tuberosity  of  the  ischium. 

The  Superficial  perine'al  fascia  consists  of  a  subcutaneous  adipose 
layer,  and  a  deeper  membranous  layer.  The  former  is  continuous  with 
the  same  structure  of  the  buttocks  and  thighs,  and,  in  the  female,  of  the 
labia.  Approaching  the  scrotum  it  gradually  merges  into  the  deeper 
membranous  layer,  and  posteriorly  it  dwindles  into  the  thin  connective 
tissue  of  the  anal  sphincter.  On  each  side  of  the  latter  it  is  continuous 
with  a  mass  of  areolar  and  adipose  tissue  occupying  the  ischio-rectal 
fossa — a  depression  several  inches  in  depth  between  the  ischium  and 
rectum. 

The  membranous  layer  of  the  superficial  fascia  is  thin  and  moderately 
strong.  It  is  connected  with  the  rami  of  the  pubes  and  ischia,  and  with 
the  tuberosities  of  the  latter ;  invests  the  ischio-cavernous  and  bulbo- 
urethral  muscles,  and  is  continuous  with  the  fascia  of  the  spongy  and  cav- 
ernous bodies.  Posteriorly,  after  investing  the  transverse  perineal  mus- 
cle, it  becomes  continuous  with  the  bottom  of  the  deep  perineal  fascia, 
the  connective  tissue  of  the  anal  sphincter,  and  the  ischio-rectal  fascia. 

The  Deep  perine'al  fascia,  or  triangular  ligament,4  is  a  strong  mem- 
brane extended  across  the  arch  of  the  pubis.  It  is  pierced  by  the  mem- 

1  Arcus  tendineus ;  ischio-pubic  arch,  3  Obturator  fascia, 

or  band.  *  Fascia  perinsei  profunda ;   ligamen- 

J  Fascia  recto-vesicalis ;    diaphragma  tuna  Camperi ;   1.  triangulare  urethrae  ; 

pelvis  ;  visceral  layer  of  the  pelvic  fas-  1.  infra-pubianum ;  perineal  ligament, 
cia ;  vesical  fascia. 


498  THE  GENERATIVE  APPARATUS. 

branous  portion  of  the  urethra ;  and  this  receives  from  it  an  investment 
which  is  continuous  with  the  fascia  of  the  prostate  gland.  It  further 
incloses  the  suburethral  glands ;  and  externally  is  continuous  with  the 
fascia  of  the  spongy  body.  In  the  female  it  is  pierced  by  the  extremity 
of  the  urethra,  and  is  continuous  with  the  fascia  of  the  vagina.  Its 
lower  border  is  continuous  with  the  superficial  perineal  fascia. 

MUSCLES  OF  THE  PEEINEUM. 

The  Ischio-cav'emous  muscle1  arises  tendinously  from  the  inner  part 
of  the  tuberosity  and  ramus  of  the  ischium,  and  from  the  commencement 
of  the  crus  of  the  cavernous  body  of  the  penis.  Its  fleshy  fibres  form  a 
thin  layer  covering  the  under  part  of  the  crus,  and  proceed  to  term- 
inate in  the  fibrous  investment  of  the  cavernous  body. 

In  the  female  the  muscle2  has  similar  relations  with  the  clitoris. 

The  action  of  the  muscle  is  usually  considered  as  aiding  to  maintain 
the  erect  condition  of  the  penis  through  compression  of  the  commence- 
ment of  the  cavernous  body.  Under  ordinary  circumstances  it  would 
appear  to  retract  or  draw  down  the  organ. 

The  Bulbo-ure'thral  muscle3  is  single,  or  rather  consists  of  two  muscles 
united  by  a  median  tendinous  line,  beneath  the  bulb  of  the  spongy  body. 
Its  fleshy  fibres  arise  from  the  perineal  centre  and  from  the  line  just  men- 
tioned, and  proceed  obliquely  outward  and  forward,  inclosing  the  bulb  of 
the  spongy  body,  and  terminate  in  the  fibrous  structure  on  the  back 
of  the  latter.  A  loop  of  the  most  anterior  of  the  fibres  passes  around 
the  cavernous  bodies  and  dorsal  vein  of  the  penis,  so  that  this  vessel  is 
compressed  in  the  contraction  of  the  muscle. 

By  compression  of  the  bulb  of  the  spongy  body  and  the  dorsal  vein 
the  bulbo-urethral  muscle  contributes  to  maintain  the  erect  condition  of 
the  penis.  Voluntarily  it  acts  in  expelling  the  last  portion  of  urine,  and 
involuntarily  in  the  emission  of  spermatic  liquid. 

The  Vag'inal  Constric'tor4  is  the  representative  of  the  foregoing 
muscle  in  the  female ;  the  corresponding  halves  of  the  bulbo-urethral 
muscle  being  separated  in  the  median  tendinous  line  of  origin  so  as  to 
inclose  the  semi-bulbs  of  the  spongy  body  and  embrace  the  orifice  of  the 

1  Musculus     ischio-cavernosus ;      m.  8  M.  bulbo-urethralis ;  m.  accelerator 
erector,  director,  or  sustentator  penis;  urinse;  m.  ejaculator  seminis;  m.  bulbo- 
m.  ischio-urethralis.  cavernosus ;  m.  bulbo-syndesmo  caver- 

2  M.  erector,  sustentator,  or  superior  nosus. 

rotundus  clitoridis  ;  m.  ischio-clitoridis,  *  M.  constrictor,  or  constrictores  va- 

or  ischio-sub-clitoridis.  ginae,  or  vulvae ;  sphincter  vaginae  ;  m. 

lati  et  plani  inferiores  clitoridis. 


THE  GENERATIVE  APPARATUS'.  499 

vagina.     A  slip  of  the  muscle1  likewise  passes  around  the  body  of  the 
clitoris  and  its  dorsal  vein. 

The  Transverse  perine'al  muscle2  arises  from  the  inner  part  of  the 
ramus  of  the  ischium,  and  proceeds  to  the  perineal  centre.  Frequently 
one  or  two  offsets3  are  situated  in  advance,  and  somewhat  higher  than  the 
main  portion  of  the  muscle. 

The  Anal  Sphincter4  is  an  elliptical  ring  of  fleshy  fibres  inclosing  the 
anus.  Its  posterior  extremity  is  attached  to  the  subcutaneous  tissue  at 
the  end  of  the  coccyx,  and  its  anterior  extremity  blends  with  the  other 
muscles  connected  with  the  perineal  centre. 

The  Anal  Elevator5  is  a  broad,  thin  plane  of  muscular  fibres  situated 
within  the  cavity  of  the  pelvis.  It  arises  from  the  inner  surface  of  the 
body  and  descending  ramus  of  the  pubis,  the  tendinous  arch  of  the  pel- 
vic fascia,  and  the  spine  of  the  ischium.  Descending  from  this  wide 
origin,  it  converges  to  be  inserted  into  the  end  of  the  coccyx,  the  side  of 
the  anus,  the  neck  of  the  bladder,  and  the  prostate  gland.  In  the 
female,  instead  of  the  latter,  it  is  attached  to  the  vagina. 

This  muscle  raises  the  whole  perineum,  in  which  action  it  is  aided  by 
the  transverse  perineal  muscle.  Anterior  offsets  have  been  described  as 
special  muscles  of  the  urethra.6 

The  Coccyge'al  muscle7  is  a  posterior  offset  of  the  preceding  muscle. 
It  arises  from  the  spine  of  the  ischium  and  the  lesser  sacro-sciatic  liga- 
ment, and  passes  with  this  to  be  inserted  into  the  side  of  the  coccyx. 

THE  MAMMAE. 

The  Mammae  or  breasts,8  the  milk-secreting  organs  of  the  female, 
exist  only  in  a  rudimental  condition  in  the  male.  Their  presence  is 
characteristic  of  the  highest  order  of  animals,  which  are  thence  named 

1  M.  attrahens  clitoridis.  ani ;  m.  sedem  attolens.     In  part  m.  ad- 

2  M.  transversus  perinei ;  m.  perinaeus  ductor,  levator,  or  compressor  prostatae. 
superficialis,  or  posterior  ;  m.  ischio-pe-  6  M.  compressor  urethras  ;    m.  c.,  or 
rimieus ;  m.  levator  ani  parvus.  constrictor  isthmi  urethras  ;  m.  constric- 

3  M.  transversus  perinei  alter ;  m.  pe-  tor  urethra  membranaceae  ;    m.  pubio- 
rinaeus  profundus,  or  anterior.  urethrales ;  transverse  compressor  mus- 

4  Sphincter  of  the  anus ;  m.  sphincter  cle  ;  Guthrie's  muscles ;  Wilson's  mus- 
ani ;  m.  s.  a.  externus,  or  cutaneus ;  m.  cles. 

constrictor  ani ;  m.  orbicularis  recti ;  m.  7  M.  coccygeus ;  m.  ischio-coccygeus  ; 

coccygio-ani;  m.  aspidiscus.  m.  levator,  or  triangularis  coccygis. 

5  Elevator  of  the  anus  ;  m.  levater  ani;  8  Sing. :    masthus ;     mastus ;    ruma  ; 
m.  1.  a.  magnus,  or  interims ;    m.  latus  uber. 


.  Birch  M.&. 
Carbon,  Pb. 

500  THE  GENERATIVE  APPARATUS. 

mammals  or  mammalia.  In  most  of  these  they  are  attached  to  the 
parietes  of  the  abdomen,  but  in  apes  and  man  they  occupy  the  front  of 
the  thorax. 

When  fully  developed  in  the  human  female,  the  mammse  form  a  pair 
of  hemispherical  prominences  slightly  divergent  from  each  other  and 
surmounted  by  a  conical  eminence,  the  nipple.  They  are  separated  by 
a  groove  in  front  of  the  sternum,  and  extend  outwardly  nearly  to  the 
axilla.  Their  base  rests  against  the  great  pectoral  muscle,  extending 
from  about  the  third  to  the  seventh  rib. 

The  Nipple1  is  of  a  roseate  or  brownish  hue,  and  is  surrounded  by  an 
areola  of  skin  of  the  same  color.  Both  enlarge  and  become  darker  in 
pregnancy,  and  the  change  to  some  degree  is  permanent.  The  skin  of 
the  nipple  is  smooth  in  the  virgin,  but  after  pregnancy  becomes  more  or 
less  wrinkled.  It  is  thin,  and  furnished  with  numerous  sensitive  papilla ; 
is  highly  vascular,  and,  under  excitement,  capable  of  erection.  At  its 
summit  are  situated  the  mouths  of  the  milk  ducts,  of  which  there  are 
fifteen  or  twenty. 

The  skin  of  the  areola  is  thin,  and  exhibits  scattered,  whitish,  pimple- 
like  eminences,2  which  are  sebaceous  glands.  These  enlarge  during 
suckling,  and  secrete  a  peculiar  fatty  substance  which  protects  the  parts 
from  the  liability  to  excoriation.  Beneath  the  skin  of  the  mammae  there 
is  a  variable  amount  of  adipose  tissue,  upon  the  extent  of  which  the 
size  and  form  of  the  breasts  greatly  depend.  It  is  divided  into  lobular 
masses  by  laminae  of  fibrous  tissue  extended  between  the  skin  and  the 
mammary  gland.  In  thin  persons  this  adipose  tissue  is  absent,  and  its 
position  is  occupied  by  an  abundance  of  areolar  tissue. 

The  Mam/mary  gland3  is  circular,  with  its  external  surface  convex 
and  prolonged  to  the  nipple.  Its  internal  surface  is  flattened,  and  ad- 
heres to  the  pectoral  muscle  by  connective  tissue,  which  may  become 
much  elongated  during  pregnancy,  from  the  increasing  weight  of  the 
mammae,  unless  they  are  supported  by  artificial  means.  From  such  an 
elongation  of  the  connection  of  the  mammae  they  hang  purse-like  from 
the  front  of  the  thorax,  with  the  nipples  directed  downward. 

The  mammary  gland  is  of  firm  consistence,  and  of  a  pinkish-white 
color.  It  is  a  racemose  gland,  composed  of  from  fifteen  to  twenty  lobes 
closely  associated  by  connective  tissue.  The  lobes  are  subdivided  into 
lobules,  and  these  consist  of  the  ultimate  vesicular  structure  observed  in 

1  Teat ;  titty  ;  dug :  pap ;   mammilla ;  papilla. 

2  Tubercles  of  the  areola. 

3  Glandula  lactifera. 


THE   GENERATIVE  APPARATUS. 


501 


other  racemose  glands,  but  the  whole  are  so  closely  united  as  to  appear 
homogeneous.  Under  the  active  state,  however,  the  lobular  constitution 
becomes  more  evident.  From  each  lobe  proceeds  a  lactiferous  duct1 
toward  the  summit  of  the  nipple,  where  it  terminates  by  a  small  orifice, 
and  thus  the  number  of  orifices  in  the  latter  position  correspond  with  the 
number  of  lobes  and  ducts  of  the  gland.  Beneath  the  areola,  the  ducts 

FIG.  314. 


SEVERAL  SMALL  LOBULES  OF  THE  MAMMARY  GLAND  OF  A  PREGNANT  WOMAN,  highly  magnified. 

become  enlarged,  especially  during  lactation,  forming  the  so-called  lac- 
tiferous sinuses.2  These  are  comparatively  small  in  the  human  female, 
but  in  some  of  the  lower  animals,  as  in  the  cow,  they  form  large  reser- 
voirs for  the  milk. 

FIG.  315. 


DIAGRAM,  EXHIBITING  THE  COURSE  OP  A  LACTIFEROUS  DUCT.    1,  summit  of  the  nipple;  2,  course  of  ihe 
ducts  through  the  latter;  3,  a  lactiferous  sinus;  4,  origin  of  the  ducts  toward  the  periphery  of  the  gland. 

The  arteries  of  the  mammary  gland  are  the  long  thoracic,  together 
with  other  branches  of  the  axillary,  and  of  the  internal  mammary  and 

1  Galactophorous  ducts;  ductus  galactophorus. 

2  Galactophorous  sinuses  ;  sinus  lactei. 


502  THE   GENERATIVE  APPARATUS. 

intercostal  arteries.  The  veins  correspond  with  the  arteries.  The  nerves 
are  derived  from  the  intercostals. 

Milk,1  the  secretion  of  the  mammary  glands,  consists   of  a  colorless 

liquid,  the  milk  plasma,  holding  in 

Fia.  316.  suspension     innumerable     fat-like 

**  corpuscles,  named  the  milk  globules. 

HP  The   milk  plasma    consists    of 

"?°o  °°o      *4g§^  water  having   in   solution   casein, 

0°  c ,  •       ^P'  lactin  or  milk-sugar,  and  salts. 

CORPUSCLES  OBSERVED  IN  MILK,  a,  milk  globules;  The     milk    globules     are    of    no 

6,  c,  d,  colostrum  corpuscles  in  various  stages.  Definite  S1Z6,  and  Consist  of  minute 
Highly  magnified.  '  . 

drops  of  fat  apparently  inclosed  in 

a  thin  film  of  coagulated  casein.  To  them  is  due  the  opaque-white  color 
of  milk,  which  constitutes  a  sort  of  an  emulsion. 

The  souring  of  milk  depends  on  the  conversion  of  its  sugar  into  lactic 
acid,  which  separates  the  casein  from  the  milk  globules,  and  coagulates 
it,  together  with  that  of  the  milk  plasma,  into  a  finely  granular  mass, 
while  the  oil  accumulates  as  cream. 

In  the  inactive  state  of  the  mammary  glands  they  secrete  only  a  very 
small  quantity  of  viscid  mucus. 

The  formation  of  milk  occurs  through  the  elaboration  of  its  constitu- 
ents within  the  secreting  cells  of  the  ultimate  gland  vesicles,  which  cells 
successively  advance  into  the  lactiferous  ducts  and  there  burst,  yielding 
up  their  contents  in  the  form  of  milk. 

At  the  commencement  of  lactation,  the  liquid  first  discharged  from 
the  mamma3  has  a  thin,  yellowish  aspect,  and  is  called  colos'trum,  This 
is  the  result  of  the  first  step  in  the  production  of  milk.  Its  main  pecu- 
liarity consists  in  its  containing  many  of  the  milk-producing  cells  in  an 
entire  state,  which  are  named  colos'tmm  corpuscles, 

1  Lac  ;  humor  lacteus ;  latex  niveus. 


CHAPTER  XL 

THE   NERVOUS   SYSTEM. 

THE  Nervous  system1  is  subdivided  into  the  cer'ebro-spinal  and  sym- 
pathetic systems.  The  former  consists  of  the  cer'ebro-spinal  axis,2  or 
the  brain  and  spinal  cord,  and  the  nerves3  distributed  thence  throughout 
the  body ;  the  latter  is  composed  of  an  intricate  arrangement  of  nerves 
and  ganglia,  intercommunicating  with  the  cerebro-spinal  system,  and 
mainly  distributed  upon  the  viscera  of  the  great  cavities.  Ganglia  are 
likewise  found  upon  most  of  the  cerebro-spinal  nerves,  several  of  which, 
however,  are  by  some  anatomists  described  as  belonging  to  the  sympa- 
thetic system. 

GENERAL  CHARACTERS  AND  STRUCTURE  OF  THE  CEREBRO- 
SPINAL  AXIS. 

The  Cer'ebro-spinal  axis,  or  the  brain,  with  its  prolongation  the 
spinal  cord,  is  a  large  mass  of  matter  of  peculiar  anatomical  and  chem- 
ical constitution.  It  is  of  about  the  consistency  of  newly-pressed 
cheese,  and  is  readily  crushed  between  the  fingers.  Its  substance, 
together  with  that  of  the  nerves  and  the  ganglia  situated  on  their  course, 
constitute  the  nerve  tissue. 

The  cerebro-spinal  axis  is  subdivided  into  the  cerebrum  and  cere- 
bellum, which  form  the  greater  part  of  the  nervous  mass,  and  the  pons, 
medulla  oblongata,  and  spinal  cord. 

The  cerebrum  and  cerebellum  are  composed,  on  their  exterior,  of  a 
reddish  or  brownish-gray  material,  named  the  gray  substance ;  on  their 
interior,  of  a  milk-white  material,  called  the  white  substance,  which  in- 
cludes a  number  of  nuclei,  laminae,  and  streaks  of  the  gray  substance. 
The  pons,  medulla  oblongata,  and  spinal  cord  are  composed,  exteriorly, 
of  the  white  substance,  and  contain  gray  substance  interiorly. 

The  two  kinds  of  nerve  substance,  in  an  unaltered  condition,  to  the  eye 

1  Systema  nervosum.  2  S.  n.  centrale ;  neural  axis  ;  cranio-spinal  axis. 

3  S.  n.  periphericum. 

(503) 


504 


THE   NERVOUS   SYSTEM. 


FIG.  317. 


appear  perfectly  homogeneous,  but  when  hardened  by  the  action  of  alco- 
hol or  other  means,  the  white  substance  readily  tears  into  fibrils,  having 
a  determinate  direction  in  every  position  ;  while  the  gray  matter  assumes 
a  more  granular  aspect. 

The  chemical  composition  of  the  nerve  substance  of  the  cerebro-spinal 
axis  approximates  the  following  :— 

Water 80 

Albuminous  matter    .........  7 

Peculiar  fatty  matters  in  association  with  phosphorus        .         .  7 

Osmazome          ..........  1 

Phosphates  of  potassa,  lime,  and  magnesia,  chloride  of  sodium, 

and  sulphur 5 

100 

The  White  substance1  of  the  brain  and  spinal  cord  is  of  compara- 
tively simple  anatomical  constitution.     Under  ordinary  circumstances, 

when  examined  beneath  the  micro- 
scope, it  appears  to  be  composed  of 
transparent  beaded  filaments2  of 
various  sizes.  The  larger  filaments, 
and  the  bead-like  dilatations  of  the 
smaller  ones,  exhibit  a  double  out- 
line or  contour,  as  if  they  were 
hollow  and  filled  with  a  transparent 
homogeneous  substance.  The  fila- 
ments are  soft,  and  with  the  slight- 
est violence  are  broken  up  into 
fragments,  which  partially  exude 
their  contents  and  assume*  a  multi- 
tude of  irregular  forms,  as  repre- 
sented in  figure  317.  Careful  in- 
vestigation shows  that  the  filaments 
are  tubular,  and  are  like  those 
composing  the  nerves,  whence  they  are  named  nerve  fibres.3  These,  in 
the  unaltered  condition,  are  separately  of  uniform  diameter,  arid  exhibit 
a  range  in  different  ones  of  from  the  TQ  J<JTJ  to  tne  4  w  °f  an  incn- 
They  are  arranged  parallel  to  one  another,  and  have  straight,  or  at  most 
only  slightly  undulating  sides.  They  are  provided  with  a  structureless 


a 


NERVE  FIBRES  op  THE  WHITE  SUBSTANCE  OP  THE 
CEREBRUM.  1,  beaded  appearance  presented  by  the 
fibres,  which  are  of  various  sizes ;  2,  various  irreg- 
ular forms  assumed  by  the  fibres  as  they  ordinarily 
appear  when  examined  mingled  with  a  little  water; 
3,  ideal  representation  of  the  unchanged  fibres. 


1  Medullary  substance ;  tubular  nerve 
substance. 

2  Fibrse   nervosae   varicosae ;  varicose 
nerve  fibres. 


3  Nerve  tubules,  or  tubes;  ultimate, 
or  primitive  nerve  fibres  or  tubes;  fibrse 
nervosae  priruitivae  ;  f.  n.  centrales. 


THE  NERVOUS   SYSTEM. 


505 


membrane  of  extreme  tenuity,  called  the  neurilem'ma,1  and  colorless, 
apparently  homogeneous  contents,  named  the  nervous  matter.2  After 
death  this  matter  in  the  larger  nerve  tubes  is  observed  to  consist  of  two 
portions,  which  have  been  named  the  med'ullary  sheath3  and  the  axis 
fibre,4  "CJie  former  incloses  the  latter,  and  has  its  outer  limit  undefined 
from  the  equally  refractive  neurilemma.  It  appears  like  viscid  oil,  and 
escapes  from  the  ruptured  nerve  tubes  in  thickly  outlined  drops  of  va- 
rious shapes.  The  axis  fibre  is  solid,  translucent,  homogeneous,  or 
sometimes  appears  faintly  granular,  and  is  elastic.  From  the  broken 
ends  of  nerve  fibres  it  is  not  unfrequently  seen  projecting  beyond  the 
exuded  drops  of  the  substance  of  the  medullary  sheath. 

Whether  the  axis  fibre  and  medullary  sheath  are  separate  structures 
during  life,  or  whether  they  are  actually  the 
result  of  a  sort  of  coagulation  of  the  nervous 
matter  subsequent  to  death,  is  a  much  disputed       , 
question. 


Fio.  318. 


''% 


The  Gray  substance5  of  the  cerebro-spinal 
axis  is  of  complex  constitution,  and  is  composed 
of  nerve  cells,  nuclei,  granular  matter,  and 
nerve  fibres.  The  exact  relationship  of  these 
different  elements  is  among  the  most  difficult 
anatomical  subjects  of  investigation,  and  their 
signification  is  variously  estimated.  By  some 
authorities  the  larger  cells  and  the  nerve  fibres 
are  alone  considered  as  true  elements  of  nerve 
structure,  while  the  abundant  granular  matter, 

nuclei,  and  smaller  cells  are  viewed  as  a  matrix  allied  to  ordinary  con- 
nective tissue. 

The  Nerve  cells6  of  the  gray  substance  range  from  about  the  ?JT>  to 
the  ^  of  a  line  in  diameter,  and  in  most  instances  are  provided  with  one, 


PORTION  OF  GRAY  SUBSTANCE, 
FROM  THE  EXTERIOR  OF  THE  CERE- 
BELLUM. 1,  two  nerve  cells  with  bi- 
polar prolongations;  2,  granular 
matter ;  3,  nuclear  bodies ;  4,  nerve 
fibres. 


1  Coat,    sheath,    or    tunic    of    nerve 
fibres ;    limitary   membrane ;    primitive 
sheath ;  vagina  interna. 

2  Neurine ;    contentum   nervosum ;  c. 
fibrarum  nervosarum. 

3  White  substance  of  Schwann ;  nerve 
medulla ;  n.  pulp. 

4  Cylinder  axis  ;  central  fibre ;  primi- 
tive band ;  axis  band ;  fibra  primitiva 
fibrse  nervosae  ;  fascia  primitiva. 


5  Substantia  grisea;  s.  cinerea;  s.  cor- 
ticalis  ;  the  cineritious  substance.    Also 
the   varieties :     substantia    ferruginea, 
flava,  ochracea,  nigra,  coerulea,  violac- 
ca,  spongiosa,  and  gelatinosa;  vesicular 
neurine. 

6  Ganglion  globules  ;  nerve  globules, 
cells,    corpuscles,   or   vesicles ;    corpus- 
cula  nervea  ;   c.  nervosa  centralia  ;  glo- 
buli  nervosi  nucleati  ;  g.  explementorii ; 
g.  nucleati  centrales. 


506 


THE   NERVOUS   SYSTEM. 


two,  or  more  processes,  from  which  they  are  called  unipolar,  bipolar,  and 
multipolar  cells,  They  have  a  delicate  wall  and  soft  granular  contents, 
with  or  without  pigmentary  matter,  upon  which  the  color  of  the  gray  sub- 
stance is  partly  due.  They  generally  possess  a  single  large,  spherical 
nucleus  ;  but  some  of  the  smaller  cells  in  the  central  portion1  of  the  gray 
substance  of  the  spinal  cord  have  several  nuclei, 

FIG.  319. 


LARGE  NERVE  CELLS  FROM  THE  ANTERIOR  HORNS  OF  THE  GRAY  SUBSTANCE  OF  THE  SPINAL  CORD,  highly 

magnified. 

The  processes  of  the  nerve  cells  are  from  one  to  twenty  or  more,  and  start 
from  any  part  of  their  periphery.  They  appear  as  hollow  prolongations, 
with  the  ordinary  cell  contents,  or  are  filled  with  homogeneous  substance, 
or  partly  with  both.  The  relation  of  these  processes  to  contiguous 
structures  has  not  been  definitely  settled.  Many  appear  to  conjoin  with 
those  of  other  cells,  thus  forming  commissures ;  some  become  continu- 
ous with  the  axis  fibre  of  nerve  fibres,  but  in  the  smallest  cells  they 
appear  to  end  without  being  connected  with  other  parts.  They  are 
often  of  considerable  length,  simple  or  branched,  and  usually  continue 
some  distance,  especially  in  the  larger  cells,  before  becoming  attenuated ; 
which  they,  however,  do  not  do  at  all  when  they  join  nerve  fibres. 

1  Substantia  grisea  centralis ;  gray  central  nucleus  of  the  cord. 


THE   NERVOUS   SYSTEM.  507 

| 

The  larger  nerve  cells,  generally  acknowledged  as  being  the  most 
important  element  of  the  gray  substance,  are  abundant  in  the  anterior 
horns  of  the  gray  matter  of  the  spinal  cord,  the  base  of  the  pos- 
terior horns,  the  surface  of  the  fourth  ventricle,  the  gray  matter  of  the 
medulla  oblongata  and  pons,  the  dentate  body  of  the  cerebellum,  the 
deeper  part  of  the  outer  layer  of  the  cortical  gray  substance  of  the  latter, 
and  in  the  gray  matter  of  the  cerebrum.  The  smaller  cells  are  most 
numerous  in  the  central  portion,  and  extremities  of  the  posterior  horns, 
of  the  gray  substance  of  the  spinal  cord,  in  the  outer  layer  of  the  corti- 
cal gray  substance  of  the  cerebellum,  and  throughout  the  cortical  layer 
of  the  cerebrum. 

The  nuclei  of  the  gray  substance  of  the  cerebro-spinal  axis  are 
more  numerous  than  the  nerve  cells,  and  are  everywhere  abundant, 
but  especially  in  the  deeper  layer  of  the  cortical  gray  substance  of  the 
cerebrum  and  cerebellum.  They  are  mostly  smaller  than  those  contained 
within  the  nerve  cells,  but  also  reach  the  size  of  those  belonging  to  the 
latter.  They  have  finely  granular  contents  and  a  nucleolus. 

The  granular  matter  of  the  gray  substance  forms  a  kind  of  matrix  in 
which  the  elements  above  described  are  imbedded.  It  is  exceedingly 
fine  and  soft,  resembling  that  contained  within  the  nerve  cells.  It  is 
everywhere  abundant,  but  in  the  superficial  portion  of  the  cortical  gray 
substance  of  the  cerebrum  and  cerebellum  is  especially  large  in  quantity. 

The  nerve  fibres  of  the  gray  substance  have  the  same  constitution  as, 
and  are  continuous  with,  those  of  the  white  substance,  but  are  much 
attenuated,  so  as  generally  not  to  be  more  than  half  the  diameter  of  the 
latter.  They  form  half  the  bulk  of  the  gray  substance  of  the  spinal 
cord  and  a  large  portion  of  the  deeper  layer  of  the  cortical  gray  sub- 
stance of  the  cerebrum  and  cerebellum. 

The  brain  and  spinal  cord  are  among  the  most  vascular  of  organs, 
and  their  capillary  blood-vessels  are  the  finest  in  the  body.  These  ves- 
sels are  most  numerous  in  the  gray  substance,  everywhere  form  an  intri- 
cate net-work,  and  are  supplied  from  the  vessels  of  the  pia  mater,  to 
which  they  again  return  the  blood. 

GENERAL  CHARACTERS   AND  STRUCTURE  OF  THE  CEREBRO- 
SPINAL  NERYES. 

The  Cer'ebro-spinal  nerves  are  connected  in  pairs  with  the  brain  and 
spinal  cord  by  their  larger  extremity,  and  are  thence  distributed  through- 
out the  body.  They  are  white  or  cream  colored,  mostly  flattened  cylin- 


508 


THE  NERVOUS   SYSTEM. 


drical  cords,  branching  in  their  course  at  acute  angles,  and  disseminated 
in  fine  filaments  in  the  various  organs  and  tissues.  With  few  exceptions 
they  anastomose  with  one  another  a  short  distance  after  their  origin, 
forming  plexuses ;  but  subsequently  anastomoses  in  the  larger  branches 
of  most  nerves  are  comparatively  unfrequent.  Many  of  the  nerves  pur- 
sue the  same  general  course  as  the  principal  blood-vessels ;  and  usually 
the  nerves,  blood-vessels,  and  lymphatics  of  an  organ  are  observed  asso- 
ciated together  with  connective  and  some  adipose  tissue. 

The  nerves  are  composed  of  bundles  of  nerve  fibres,  the  larger  ones, 
like  the  muscles,  being  composed  of  primary  and  secondary  bundles, 
which  are  associated  with  an  abundance  of  connective,  mingled  with 


TRANSVERSE  SECTION  OF  THE  SMALL  SCIATIC  NERVE, 
magnified  fifteen  diameters,  a,  general  sheath  of 
the  nerve ;  b,  sheath  of  the  secondary  bundles ;  c, 
the  primary  bundles  of  nerve  fibres.  From  the 
calf. 

some  elastic  tissue,  which  constitute 
their  sheath.1  The  sheath  of  the 
primary  bundles  is  delicate,  trans- 
parent, and  assumes  the  character 
of  structureless  membrane2  with 
scattered  nuclei.  The  larger  the 
nerve,  the  greater  is  its  number  of  bundles  of  nerve  fibres ;  and  the 
branching  of  a  nerve  is  the  sending  off  of  such  bundles,  and  finally  of 
the  individual  nerve  fibres.  The  anastomosis  of  nerves  consists  of 
an  interchange  of  bundles  of  nerve  fibres.  In  the  course  of  a  nerve 
trunk  the  primary  bundles  frequently  subdivide  and  anastomose  ;  but  in 
all  cases  the  nerve  fibres  retain  their  continuity. 

The  nerve  fibres3  of  the  nerves  have  the  same  constitution  as  those 
of  the  white  substance  of  the  brain  and  spinal  cord,  but  are  generally 


MODE  OF  ANASTOMOSIS  AND  BRANCHING  OF  NERVES. 

1,  2,  two  fasciculi  of  nerve  fibres ;  3,  a  branch  of 
three  fibres;  4,  branch  of  two  fibres;  5,  6, 
branches  of  single  fibres ;  7,  anastomosis  between 
two  nerves. 


1  Neurilemma ;  neurymen  ;  perineu- 
rion ;  tunica,  membrana,  involucrum, 
vagina,  capsula,  fistula,  tubulus,  or  in- 
dumentum nervorum. 


2  Perineurium. 

3  Ultimate  or  primitive  nerve  fibres  ; 
nerve  tubes,  or  tubules  ;  fibres  nervocse  ; 
tubuli  nervei ;  fila  nervea ;  tubular  nerve 
fibres. 


THE  NERVOUS   SYSTEM. 


509 


much  larger.  In  every  case  they  continue  undivided,  and  of  nearly 
uniform  diameter  from  their  origin 
to  their  destination.  The  difference 
in  strength  of  the  nerves  and  white 
substance  of  the  cerebro -spinal 
axis  depends  on  the  association  of 
connective  tissue  with  the  former, 
and  its  absence  in  the  latter.  For 
the  same  reason,  a  house-fly  or 
other  insect,  with  its  complex  mus- 
cular and  nervous  system,  its  diges- 
tive and  vascular  apparatus,  is 
readily  crushed  between  the  fingers ; 
while  the  more  bulky  vertebrate 
animal  is  protected  from  the  same 
easy  destruction  by  what  might  be 
called  its  skeleton  of  bone,  gristle, 
and  fibrous  tissue. 

The  nerves  are  duller,  less  glisten- 
ing and  dense  than  tendons,  with 
which  the  unaccustomed  eye  is  apt 
to  confound  them.  The  transverse 
striation  exhibited  by  their  primary 
bundles  depends  on  the  slightly 
wavy  or  undulant  course  of  the 
nerve  fibres,  and  is  found  to  disappear  on  stretching  the  nerves. 

The  nerves  are  abundantly  supplied  with  blood-vessels,  which  form  a 
capillary  net- work,  with  elongated  meshes,  among  the  bundles  of  nerve 
fibres. 


STRUCTURE  OF  NERVE  FIBRES,  partly  ideal.  1,  a 
nerve  fibre  represented  in  the  fresh  condition,  ex- 
hibiting in  succession  its  neurilemmft,  medullary 
sheath,  and  axis  fibre;  2,  3,  4,  5,  exhibit  the  same 
constituents ;  the  medullary  sheath  indicated,  as  it 
appears  shortly  after  death,  by  heavy  outlines; 
the  axis  fibre  represented  as  dotted.  In  4,  5,  the 
axis  fibre  is  seen  projecting  from  the  cut  ends  of 
the  nerve  fibres.  In  4,  the  medullary  sheath 
is  seen  exuding  in  drops  through  a  rupture  of  the 
neurilemma. 


ORIGIN  AND  TERMINATION  OF  THE  CEREBRO-SPINAL  NERVES. 

The  extremity  of  the  cerebro-spinal  nerves  connected  with  the  brain 
and  spinal  cord  is  called  their  origin  or  root,  while  the  peripheral  ex- 
tremity is  named  their  termination.  These  terms  are  employed  inde- 
pendently of  their  functional  significance,  as  most  nerves  are  composed 
of  fibres,  of  which  different  ones  transmit  impressions  in  opposite  direc- 
tions, and  therefore  the  extremities  would  more  properly  be  designated 
their  central  and  peripheral  connections. 

A  nerve  is  said  to  originate  by  a  single  root  when  its  bundles  of  fibres 
emanate  from  one  spot  or  along  the  same  line  of  the  cerebro-spinal  axis ; 
and  it  is  said  to  arise  by  two  or  more  roots,  when  its  bundles  of  fibres 


510  THE  NERVOUS   SYSTEM. 

form  a  corresponding  number  of  series  emanating  from  different  points 
of  the  cerebro-spinal  axis. 

The  fibres  composing  the  roots  of  the  nerves  are  traceable  into  the 
substance  of  the  brain  and  spinal  cord,  within  which  they  are  con- 
tinuous with  nerve  fibres  of  the  white  substance,  or  become  connected 
with  the  neighboring  gray  substance.  This  interior  connection  of  the 
nerves  is  called  their  deep  or  real  origin,  while  their  exterior  connection 
with  the  cerebro-spinal  axis  is  named  their  superficial  or  apparent 
origin.  To  ascertain  the  real  origin  of  the  nerves  is  among  the  most 
difficult  subjects  of  anatomical  investigation,  and  our  knowledge  in  this 
respect  is  very  imperfect. 

From  their  superficial  origin  the  bundles  of  fibres  of  the  roots  of  the 
nerves  become  invested  with  a  delicate  sheath  of  connective  tissue,  con- 
tinuous with  the  pia  mater.  If  the  bundles  of  nerve  fibres  are  separated 
as  they  emerge  from  the  cerebro-spinal  axis  they  converge  together,  and 
the  roots  of  the  nerves  perforate  the  dura  mater,  to  pass  through  foramina 
of  the  cranium  and  vertebral  column.  In  the  course  of  the  roots  of  the 
nerves  to  the  dura  mater,  the  arachnoid  membrane  is  reflected  around 
them.  Externally  to  the  dura  mater,  the  nerves  become  invested  with  a 
strong  sheath  of  connective  tissue,  which  is  continuous  with  the  latter 
membrane,  and  much  increases  the  size  of  the  nerves. 

Approaching  their  termination  in  the  different  organs,  the  nerves  form 
frequent  anastomoses ;  but,  as  in  the  case  of  the  trunks  and  larger 
branches  of  the  nerves,  these  anastomoses  consist  alone  of  an  inter- 
change of  nerve  fibres.  The  mode  in  which  the  latter  end  in  the  various 
tissues,  for  the  most  part  remains  an  unsettled  question.  Until  within  a 
short  period  it  was  asserted,  and  the  view  generally  adopted,  that  the 
nerves  terminated  in  loops  :  that  is  to  say,  pairs  of  nerve  fibres  finally 
conjoined  in  an  arching  or  sling-like  manner.  Recent  observations  are 
not  confirmatory  of  such  a  conclusion.  In  the  muscles,  the  nerve  fibres 
sent  off  separately  subdivide,  and  finally  lose  their  medullary  sheath, 
the  axis  fibre  alone  ending  among  the  muscular  fibres. 

In  some  instances,  the  nerves  terminate  in  peculiar  capsular  bodies,  of 
which  three  varieties  have  been  detected. 

The  most  remarkable  of  the  nerve  capsular  bodies  are  the  so-called 
Pacin'ian  corpuscles,1  attached  in  greatest  number  along  the  digital 
nerves  of  the  fingers  and  toes,  and  occasionally  on  other  nerves.  These 
corpuscles  are  oval,  pyriform,  or  reniform,  from  half  a  line  to  a  line 
long,  of  a  pearly  lustre,  and  consist  of  a  series  of  capsules  or  concen- 

1  Pacinian  bodies;  corpuscles  of  Vater;  Valerian  corpuscles;  Vater-Pacini'schen 
Korperchen;  papillae  nervese. 


THE   NERVOUS   SYSTEM. 


511 


The  outer  capsules 


FIG.  323. 


trie  layers  of  fibrous  tissue  with  scattered  nuclei, 
are  separated  more  widely  than  the  inner  ones, 
and  the  interspaces,  as  well  as  the  central 
cavity  of  the  corpuscle,  are  filled  with  a  color- 
less liquid.  Each  corpuscle  is  attached  to  the 
nerves  by  a  pedicle  of  fibrous  tissue,  through 
which  extends  a  single  nerve  fibre.  The  latter, 
after  penetrating  the  series  of  capsules,  term- 
inates by  sending  its  axis  fibre  into  the  cen- 
tral cavity  of  the  corpuscle,  at  the  top  of  which 
it  ends  by  a  simple  or  divided  extremity. 

The  second  variety  of  nerve  capsular  bodies 
are  the  so-called  tactile  corpuscles.1  These 
are  oval  bodies  found  in  many  of  the  papillae 
of  touch  of  the  fingers  and  palms  of  the  hands, 
and  the  toes  and  soles  of  the  feet.  They 
average  the  ^  of  a  line  long,  and  consist  of 
a  single  capsule  of  structureless  membrane 
with  transverse  nuclei.  They  are  filled  with  a 
finely-granular  matter,  and  have  entering  into 
them  usually  two,  but  sometimes  one,  or  even 
three  or  four,  nerve  fibres. 

7  digital    nerve;    4,   several   nerve 

The   third  variety2   of  the   nerve   capsular    fibres;  5,  the  fibrous  sheath;  6, 
bodies  are  transparent,  spherical  corpuscles  of 
about  the  ^  of  a  line  in  diameter,  discovered 
in  the  conjunctiva  of  the  eyeball,  the  mucous    Pacinian  corPuscles  atta<hed>  of 


PACINIAN  CORPUSCLES,  from  the 
digital  nerve  of  the  finger  of  a 
new-born  child.  1,  much  magni- 
fied corpuscle,  which  was  reniform ; 
2,  the  pedicle;  3,  portion  of  the 


nerve  fibre  to  the  corpuscle;  7, 
axis  fibre  of  the  nerve  fibre;  8, 
portion  of  a  digital  nerve  with 


the  natural  size. 


membrane  of  the  root  of  the  tongue  and  soft 
palate,  and  the  skin  of  the  glans  penis  and  clitoridis.  They  are 
filled  with  a  soft,  transparent,  homogeneous  substance,  and  have  entering 
into  them  one  or  two  branches  of  a  nerve  fibre. 


GENERAL  CHARACTER  AND  STRUCTURE  OF  THE  SYMPA- 
THETIC NERVES. 

The  nerves  of  the  sympathetic  system  are  mostly  reddish  gray3  or 
grayish  white,3  a  few  of  the  larger  trunks  being  white,  as  in  the  case  of 
the  cerebro-spinal  nerves.  They  are  generally  much  smaller  than  the 


1  Corpusculatactus;  tactile  corpuscles 
of  Wagner,  or  of  Meissner ;  Wagner- 
Meissner'schen  Tastkorperchen! ;  axile 
bodies ;  touch  corpuscles. 


2  Corpuscles  of  Krause  ;  Krause'schen 
Endkolben. 

3  Nervi   molles  ;    n.  grisei ;    fasciculi 
nervosi  molles. 


512 


THE  NERVOUS   SYSTEM. 


latter,  and  are  associated  with  many  ganglia,  from  which  the  sympathetic 
has  likewise  been  called  the  gan'glion'ic  system  of  nerves.  In  their 
course  to  the  organs  they  supply,  they  usually  follow  the  blood-vessels, 
upon  which  they  form  exceedingly  intricate  plexuses. 

The  sympathetic  nerves  are  composed  of  nerve  fibres,  like  those  of 
the  cerebro-spinal  system  in  association  with  others  of  peculiar  charac- 
ter, called  gray  fibres.1  The  white  nerve  fibres  are  generally  much  finer 
than  those  of  the  cerebro-spinal  nerves,  are  most  numerous  in  the  white 

trunks  of  the  sympathetic 
system,  and  are  compar- 
atively few  in  the  reddish- 
gray  nerves. 

The  gray  fibres1  are 
far  more  numerous  than 
the  white  ones  in  the  red- 
dish-gray and  grayish- 
white  sympathetic  nerves. 
They  exist  in  the  form  of 

ELEMENTS  OF  THE  SYMPATHETIC  SYSTEM.  A,  portion  of  a  nerve  bands,  averaging  the  gj^ 
highly  magnified :  a,  nerve  fibres ;  b,  gray  fibres  with  nuclei.  B,  Qf  ft  jjne  jn  Breadth  In 
three  nerve  cells  from  a  ganglion. 

structure  they  appear 

faintly  granular,  indistinctly  striated  or  homogeneous,  and  are  provided 
with  elongated  oval  nuclei.  Whether  the  gray  fibres  are  a  peculiar  ele- 
ment of  the  nervous  structure,  or  whether  they  are  to  be  viewed  as  a 
variety  of  connective  tissue,  is  a  much-disputed  question. 


GENERAL  CHARACTER  AND  STRUCTURE  OF  THE  GANGLIA. 

The  Gan'glia,  or  gan'glions,2  are  rounded  bodies  situated  in  the 
course  of  many  of  the  nerves.  Thus,  several  belong  to  the  trifacial, 
glosso-pharyngeal,  and  pneumogastric  nerves ;  one  exists  on  the  pos- 
terior root  of  each  spinal  nerve ;  and  a  numerous  series  are  found  on  the 
sympathetic  nerves.  They  are  mostly  elliptical  or  spheroidal,  but  present 
many  varieties  of  form. 

The  ganglia  are  viewed  as  sources  of  nerve  power,  and  hence,  like  the 
brain  and  spinal  cord,  are  frequently  called  nerve  centres.  The  term  is 
likewise  often  applied  to  the  collections  of  gray  substance  of  the  cerebro- 
spinal  axis. 


1  Fibres  of  Remak ;  gelatinous  fibres. 

2  Ganglia    nervorum ;    nervous   gan- 
glions ;  ganglia,  gangliones,  nodi,  noduli, 
or  tubercula  nodosa  nervorum ;  tumores, 


or  plexus  ganglioformes ;  diverticula 
spirituum  animalium;  ganglia  of  in- 
crease; formative  ganglia. 


THE   NERVOUS   SYSTEM. 


513 


FIG.  325. 


The  ganglia  are  reddish  gray  or  grayish  white,  and  of  firm  consistence. 
They  appear  like  knots  or  swellings  in  the  course  of  the  nerves,  and  are 
furnished  with  a  tightly-adherent 
membrane  continuous  with  the 
sheath  of  the  latter.  In  structure 
they  consist  of  a  mass  of  nerve  cells- 
imbedded  in  a  stroma  of  connective 
tissue,  and  are  traversed  by  nerve 
fibres  associated  with  gray  fibres. 

The  nerve  cells  of  the  ganglia 
resemble  those  of  the  gray  sub- 
stance of  the  cerebro-spinal  axis, 
but  are  more  uniformly  of  large 
size,  ranging  from  about  the  y^oo 
to  the  -gju  of  an  inch.  They  are 
globular  or  oval,  and  generally 
unipolar  or  bipolar,  though  both 
apolar  and  multipolar  cells  also 
appear  to  exist.  The  processes  of 
the  nerve  cells  are  continuous  with 
the  nerve  fibres  passing  to  and  from 
the  ganglion. 

In  the  ganglia  of  the  cerebro- 
spinal  nerves,  the  cells  are  generally  larger  than  in  those  of  the  sympa- 
thetic system. 

The  nerve  fibres  partly  traverse  the  ganglia  without  forming  any  at- 
tachment to  the  cells,  while  others  are  continuous  with  them. 

The  gray  fibres  of  the  ganglia  are  like  those  of  the  sympathetic  nerves, 
and  are  especially  abundant  in  the  sympathetic  ganglia,  in  which  they 
occupy  the  position  of  a  stroma  to  the  nerve  cells. 

The  stroma  of  the  cerebro-spinal  nerves  appears  as  a  homogeneous  or 
feebly  striated  connective  tissue  furnished  with  nuclei,  and  on  isolated 
nerve  cells  looks  like  an  especial  investment  to  them. 

Like  other  nerve  centres,  the  ganglia  are  abundantly  furnished  with 
capillary  blood-vessels. 


NERVE  CELLS  FROM  THE  SEMILUNAR  GANGLION  OF  THE 
TRIGEMINAL  NERVE  OF  A  CAT,  highly  magnified.  1, 
nerve  cell  exhibiting  the  origin  of  a  nerve  fibre :  a, 
sheath  of  the  cell  and  nerve  fibre  with  nuclei ;  6, 
the  nerve  cell  within ;  c,  the  nerve  fibre  within  its 
sheath :  2,  cell  with  the  origin  of  a  nerve  fibre  de- 
prived of  its  sheath;  3,  nerve  cell  without  sheath 
or  nerve  fibre. 


THE  CEREBRO-SPINAL  AXIS,  OR  BRAIN  AND  SPINAL  CORD. 

The  Cer'ebro-spinal  axis  consists  of  the  brain,  which  occupies  the 
cavity  of  the  cranium,  and  the  spinal  cord,  which  is  a  prolongation  of 
the  former  extending  downward  into  the  vertebral  canal.  Besides  the 

33 


514  THE  NERVOUS  SYSTEM. 

skull  and  vertebral  column,  the  cerebro -spinal  axis  is  further  enveloped 
in  three  membranes,  the  dura  mater,  arachnoid,  and  pia  mater.  From  it 
originate  the  cerebro-spinal  nerves,  or  the  cer'ebral  nerves  and  the 
spinal  nerves.  It  is  symmetrical,  the  two  halves  being  in  contact,  and 
united  along  the  median  line  by  commissures  of  nerve  substance. 

The  term  com'missure,1  frequently  employed  in  anatomy,  generally  im- 
plies the  union  of  symmetrical  parts.  In  the  nervous  system  it  applies 
to  the  conjunction  of  two  parts  of  the  brain  or  spinal  cord ;  the  union  of 
two  nerves  in  the  median  line  of  the  body,  to  nerves  between  two  or 
more  ganglia ;  and  to  the  fibres  uniting  nerve  cells. 

THE  BRAIN. 

The  Brain,2  the  seat  of  the  intellect,  the  will,  the  sensations,  and  the 
emotions,  is  the  great  nervous  mass  which,  with  its  enveloping  mem- 
branes, completely  fills  the  cavity  of  the  cranium. 

The  size  and  weight  of  the  brain  varies  with  the  race,  sex,  age,  and 
individual.  It  is  largest  in  the  white  race  ;  and,  all  other  circumstances 
being  equal,  such  as  race,  sex,  age,  size  of  body,  and  health,  its  bulk 
bears  a  general  relationship  with  the  development  of  intellect. 

Its  weight  in  the  adult  white  male  averages  near  fifty  ounces  avoir- 
dupois ;  in  the  female,  forty-five  ounces.  In  its  relation  with  the  weight 
of  the  body,  the  difference  between  the  two  sexes  is  very  little.  In 
relation  with  the  size  of  the  body  at  birth,  the  brain  bears  the  propor- 
tion of  one  to  twenty ;  in  the  adult,  of  one  to  thirty-five. 

The  human  brain  is  larger  than  in  any  other  animal  except  the 
species  of  elephants  and  whales ;  but  in  relation  with  the  size  of  the 
nerves  given  off  from  its  base,  it  is  larger  than  in  any  animal  without 
exception.  In  relation  with  the  size  of  the  body,  the  brain  is  larger  in 
some  small  mammals  and  birds  than  in  man,  as  for  instance,  in  the  little 
monkey  Oustiti,  the  field  mouse,  and  the  canary  bird. 

In  the  infant  the  brain  is  of  a  soft,  pulpy  consistence,  but  gradually 
assumes  the  firmness,  in  the  adult,  of  newly-pressed  cheese.  Its  specific 
gravity  is  about  equal  to  or  a  very  little  greater  than  water.  It  is  for 
the  most  part  of  a  reddish-ash  color  on  the  exterior,  and  is  generally 
ovoid  in  form,  with  the  broader  extremity  posterior.  Its  upper  part  is 
uniformly  convex,  but  its  lower  part,  called  the  base,  is  uneven.  It 
exhibits  four  well-marked  divisions  of  unequal  size,  named  the  cere- 
brum, cerebellum,  pons,  and  medulla  oblongata. 

1  Commissura.  2  Encephalon  ;  cerebrum. 


THE   NERVOUS   SYSTEM.  515 


THE  CEREBRUM. 

The  Cerebrum1  forms  about  six-sevenths  of  the  mass  of  the  brain, 
and  extends  the  whole  length  and  breadth  of  its  upper  part.  It  is  half 
ovoid,  with  the  narrow  extremity  forward,  the  convex  side  upward,  the 
base  downward,  and  the  broadest  part  opposite  the  parietal  protuber- 
ances. 

A  deep  cleft,  the  great  longitudinal  fissure,2  extends  the  entire  length 
of  the  upper  part  of  the  cerebrum,  and  the  whole  depth  of  its  fore  and 
back  part.  It  accommodates  the  cerebral  falx,  and  along  its  upper 
boundary  the  superior  longitudinal  sinus. 

The  lateral  halves  of  the  cerebrum  are  named  its  hemispheres.3  These 
form  vertical  planes  next  the  longitudinal  fissure,  have  their  outer  sur- 
face convex,  and  their  under  part  forming  the  three  pairs  of  cer'ebral 
lobes. 

The  anterior  lobes4  of  the  cerebrum  occupy  the  anterior  fossae  of  the 
base  of  the  cranium,  and  therefore  rest  above  the  position  of  the  orbits. 

The  middle  lobes5  occupy  the  middle  fossae  of  the  cranial  cavity,  and 
are  the  deepest  portions  of  the  cerebrum.  They  are  separated  from  the 
anterior  lobes  by  the  Syl'vian  fissure,6  which  curves  outwardly,  and 
receives  the  small  wings  of  the  sphenoid  bone. 

The  posterior  lobes7  have  no  dividing  line  from  those  in  advance,  and 
are  constituted  by  the  portions  of  the  cerebrum  resting  upon  the  tento- 
rium,  or  situated  above  the  cerebellum.  In  the  upper  view  of  the  brain 
they  completely  conceal  the  latter,  and  their  under  surface  is  somewhat 
hollowed,  to  accommodate  the  prominent  upper  part  of  the  cerebellum. 

The  cerebral  hemispheres  have  their  surface  everywhere  thrown  into 
winding  eminences  called  convolutions,8  separated  by  deep  fissures,9 
which  receive  processes  of  the  pia  mater. 

1  Cerebrum  magnum ;  encephalon ;  the  6  Lobi  medii ;  1.  descendentes. 
brain  ;  the  great  brain.  <>  Fissura,  or  fossa  Sylvii ;  fissura  an- 

2  Superior  longitudinal  sinus ;  fissura,  terior ;  f.  a.  inferior  et  externa ;  f.  infe- 
or  scissura  cerebri  longitudinalis ;  f.  c.  1.  rior ;  f.  transversa. 

superior,  inferior,  et  horizontalis  poste-  7  Lobi  posteriores.     The  middle  and 

rior;  interlobular  fissure.  posterior    together    named  lobi    poste- 

3  Hemisphaeria  cerebri;  h.  c.  et  pars  riores;  1.  majores;  1. temporo-occipitales. 
media  cerebri.  »  Cerebral  circonvolutions ;  gyri ;  pro- 

4  Lobi  anteriores ;  1.  minores.  cessus  enteroidei  cerebri. 

9  Sulci ;  anfractuosities. 


516  THE  NERVOUS   SYSTEM. 

The  Convolutions  of  the  cerebrum  are  nearly  of  uniform  diameter,  and 
are  rounded  at  the  borders  of  the  fissures  separating  them,  but  are  rather 
flattened  at  the  summit.  Their  course  is,  however,  not  symmetrical  on 
the  two  hemispheres,  nor  are  they  alike  in  two  individuals,  though  there 
is  sufficient  correspondence  in  their  position  and  general  direction  to 
permit  of  their  being  identified.  One1  of  the  most  characteristic  of 
these  convolutions  arches  over  the  corpus  callosum  on  each  side  ;  another,2 
less  well  marked,  borders  the  great  longitudinal  fissure ;  and  a  third3 
borders  the  Sylvian  fissure,  and  incloses  a  small  group  of  convolutions* 
concealed  within  the  latter. 

The  exterior  of  the  cerebrum  is  composed  of  gray  substance  called, 
from  its  position,  cortical,5  while  the  interior  consists  of  white  substance 
named,  in  contradistinction,  medullary.6  In  a  horizontal  section  of  the 
cerebral  hemispheres,  they  exhibit  a  central  oval  surface7  of  white  sub- 
stance spotted  with  minute  red  points  arising  from  the  division  of  blood- 
vessels. The  circumference  of  the  plane  of  white  substance  is  observed 
to  form  many  processes  corresponding  with  the  divided  convolutions. 
These  processes  are  further  noticed  to  be  everywhere  inclosed  by  the 
cortical  gray  matter,  which  forms  a  layer  of  uniform  thickness,  and  fol- 
lows the  course  of  all  the  convolutions  and  fissures  of  the  cerebral  hemi- 
spheres. In  a  section  of  the  hemispheres,  on  a  level  with  the  corpus 
callosum,  this  appears  as  a  bridge  of  white  substance  associating  the  oval 
centres8  of  the  same  material  of  the  cerebrum. 

In  a  view  of  the  base  of  the  brain,  the  posterior  lobes  of  the  cerebrum 
are  concealed  by  the  cerebellum.  In  advance  of  this  are  the  medulla 
oblongata  and  pons,  and  in  front  of  the  latter,  along  the  median  part  of 
the  cerebrum,  the  following  are  observed  in  succession :  the  cerebral 
crura,  the  mammillary  eminences,  the  infundibulum,  the  pituitary  body, 
the  optic  nerves  and  commissure,  and  the  olfactory  nerves. 

The  Crura  of  the  cer'ebrum9  are  two  large  cylindroid  bodies  diverg- 

1  Great  convolution  of  the  corpus  callo-          6  Tubular,  or  fibrous  substance;  me- 
sum ;  internal  convolution  of  the  hemi-      dulla  cerebri. 

spheres  ;    gyrus   fornicatus ;    processus          7  Centrum  semi-ovale ;  c.  ovale  Vieus- 
cristatus.  senii ;  c.  ovale  minus ;  lesser  oval  centre 

2  Great  convolution  of  the  circumfer-      of  Vicq-d'Azyr. 

ence  of  the  hemispheres;  marginal  con-  8  Greater  oval  centre;  centrum  ovale 

volution  of  the  longitudinal  fissure.  Vieussenii. 

3  Convolution  of  the  Sylvian  fissure.  9  Crura  cerebri ;    pedunculi  cerebri  ; 

4  Island  of  Reil ;    insula ;    i.   Reilii ;  processus   medullares   cerebri ;    caudex 
gyri  operti.  cerebri ;    crura   anteriora   medulloe  ob- 

5  Cineritious,  or  vesicular  substance.  longatae  ;  peduncles  of  the  brain ;  cere- 

bral peduncles. 


THE   NERVOUS   SYSTEM. 


517 


ing  from  the  fore  part  of  the  pons  into  the  cerebral  hemispheres,  at  the 
inner  side  of  their  middle  lobes.  They  are  longitudinally  striated,  and 
composed,  on  the  exterior,  of  white  substance.  On  the  interior  they  con- 
tain a  collection  of  gray  substance,1  which  appears  as  a  crescentoid  layer 
in  a  transverse  section  through  them. 

FIG.  326. 


BASE  OF  THE  BRAIN.  1,  anterior  lobes  of  the  cerebrum;  2,  middle  lobes;  3,  posterior  lobes;  4.  5,  ante- 
rior and  posterior  extremities  of  the  great  longitudinal  fissure;  5,  Sylvian  fissure;  7.  anterior  perforated 
space;  H,  iufundibulum;  9,  mammillary  eminences;  10,  posterior  perforated  space;  11,  crura  of  the  cere- 
brum; 12,  pons;  13,  medulla  oblongata;  14,  pyramidal  bodies;  14*,  decussation  of  the  pyramids;  15,  oli- 
vary body ;  16,  restiform  body ;  17,  hemispheres  of  the  cerebellum ;  18,  vermiform  process  at  the  bottom 
of  the  fissure  separating  the  latter ;  19,  crus  of  the  cerebellum ;  20,  pneumogastric  lobule  of  the  cerebel- 
lum; 21.  fissure  which  accommodates  the  olfactory  nerve,  22;  23,  bulb  of  the  olfactory  nerve;  24,  optic 
commissure;  25,  oculo-motor  nerve;  26,  pathetic  nerve;  27,  trifacial  nerve;  2%  abducent  nerve;  29,  facial 
nerve;  30,  auditory  nerve ;  31,  glosso-pharyngeal  nerve;  32,  pneumogastric  nerve;  33,  accessory  nerve ; 
34,  hypoglossal  nerve. 

The  interval2  separating  the  crura  at  its  fore  part  includes  the  mam- 
millary eminences  and  the  infundibulum.  At  its  posterior  angle  it  forms 
a  deep  pit,  which  is  separated  from  the  third  ventricle  by  some  mingled 

1  Locus  niger;   substantia  nigra ;  stratum  nigrum. 

2  Interpeduncular  space. 


518  THE   NERVOUS   SYSTEM. 

gray  and  white  substance  perforated  by  a  number  of  small  blood-vessels, 
and  hence  named  the  posterior  perforated  space.1 

The  Mam'millary  eminences2  are  two  small,  white,  spherical  bodies, 
in  contact  with  each  qther,  immediately  in  advance  of  the  space  just 
mentioned.  They  are  connected  above  with  the  anterior  crura  of  the 
fornix,  and  contain  some  gray  substance.3 

The  Infundib'ulum,*  as  expressed  by  the  name,  is  a  funnel-shaped 
body  included  between  the  manimillary  eminences  behind,  and  the  optic 
commissure  in  front.  It  is  composed  of  gray  substance,  is  hollow,  and 
forms  part  of  the  bottom  of  the  third  ventricle.  Its  broad  base5  narrows 
to  a  tubular  process,  which  is  directed  obliquely  downward  and  forward, 
and  is  closed  at  the  extremity. 

The  Pitu/itary  body6  occupies  the  corresponding  fossa  of  the  sphe- 
noid bone,  and  is  connected  with  the  end  of  the  infundibulum.  It  is 
reddish  gray,  of  firm  consistence,  and  presents  an  anterior  transversely 
reniform  lobe,  and  a  smaller  posterior  rounded  one.  Its  structure  con- 
sists of  a  stroma  of  connective  tissue,  with  many  capillary  blood-vessels 
mingled  with  granular  matter,  nuclei,  and  nucleated  cells. 

The  Optic  com'missure,7  situated  in  front  of  the  infundibulum,  is  formed 
by  the  conjunction  of  the  optic  tracts  converging  from  the  outer  side  of 
the  cerebral  crura.  It  and  its  connections  will  be  more  particularly  de- 
scribed in  the  account  of  the  optic  nerves. 

Between  the  optic  commissure  and  the  roots  of  the  olfactory  nerves, 

1  Substantia  perforata  postrema,  pos-  *  Funnel ;    funnel  of  the  middle  ven- 
terior,  or  media ;  basis  ventriculi  tertii ;  tricle ;  pelvis,  choana,  cyathus,  concha, 
antrum  ;  pons  Tarini.  scyphus,  lacuna,  aquaeductus,  embolum, 

2  Eminentiae  mammillares,   candican-  labrum,  concavitatis  conchularis,  or  pro- 
tes,  glandulosee,  papillares,  or  medulla-  cessus    orbicularis   cerebri;     tubercirfe- 
res ;  bulbi  fornicis ;  bulbs  of  the  fornix ;  reum  cum  infundibulo. 

b.    priorum     crurum   fornicis ;     globuli  5  Tuber  cinereum ;  substantia  perfo- 

medullares;  g.  albi;  corpora  alba,  mam-  rata  media  posterior. 

millaria,  albicantia,  or  glandularia ;  pro-  6  Glandula    pituitaria,     pituitosa,    or 

tuberantiae  crurum  medullae  oblongatae ;  basilaris ;  hypophysis,  appendix,  or  ap- 

p.   glandulosae  ;    p.   orbiculares  ;    tuber-  pendicula  cerebri ;  caput  rosae  ;    colato- 

cula  mammillaria,  hemispherica,  or  pisi-  rium  ;    labrum  ;     lacuna ;    infusorium ; 

formia;  prominently  albicantes  ;   glan-  concha;  pelvis;  p.  colatoria;  sentina  en- 

dulae  sub-infundibulo  ;   g.  candicantes ;  cephali. 

processus  glandules:  protensiones  gran-  7  Chiasma  opticum;  chiasm  of  the  op- 

dulares  ;  testiculi  cerebri ;  mammae  mu-  tic  nerves ;    chiasma  nervorum  optico- 

liebres.  rum. 

3  Nucleus  griseus. 


THE   NERVOUS   SYSTEM. 


519 


FIG.  327. 


on  each  side,  are  the  anterior  perforated  spaces,1  so  called  from  their 
presenting  numerous  small  apertures  for  vessels  which  penetrate  to  the 
interior  of  the  cerebrum. 

On  pressing  apart  the  cerebral  hemispheres,  .at  the  bottom  of  the 
great  longitudinal  fissure,  a  convex  white  body,  the  corpus  callosum,  is 
observed  to  connect  the 
former,  and  extend  for 
several  inches  along  the 
latter. 

The  Corpus  callo'sum,2 
or  great  cer'ebral  com'- 
missure,  in  a  section  of 
the  brain  on  a  level  with 
it,  appears  as  a  bridge 
of  white  substance,  about 
three  inches  long  and 
three-fourths  of  an  inch 
wide,  uniting  the  central 
white  masses  of  the  cere- 
bral hemispheres.  It 
reaches  farther  forward 
than  backward,  and  is 
narrower  anteriorly.  Its 
upper  surface3  arches  in 
the  length,  and  is  trans- 
versely striated,4  but  ex- 
hibits on  each  side  of  the 
median  line5  a  narrow 
tract  of  longitudinal 
stria?.6  Its  anterior  and  posterior  borders  are  thick  and  rounded,  and 
are  separated  by  fissures  from  the  contiguous  gray  substance  of  the  cere- 
bral hemispheres. 

In  a  vertical  section  of  the  brain,  along  the  great  longitudinal  fissure, 


TRANSVERSE  SECTION  OF  THE  HEMISPHERES  OF  THE  CEREBRUM  ON 
A  LEVEL  WITH  THE  CORPUS  CALLOSUM.  1,  white  substance  of  the 
hemispheres,  dotted  with  divided  capillary  vessels ;  2,  gray  sub- 
stance on  the  convoluted  exterior;  3,  corpus  callosum,  with  the 
direction  of  its  fibres  indicated  by  transverse  striae;  4,  longitud'- 
nal  median  stria? ;  5,  anterior  and  posterior  portions  of  the  great 
longitudinal  fissure. 


1  Substantia    perforata    anterior;    s. 
cribrosa  anterior ;  lamina  cribrosa  cere- 
bri ;   substantia  perforata  antica  media, 
et  partes  laterales  substantiae  perforates 
anticse. 

2  Commissura  magna,  or  maxima  cere- 
bri ;   trabs  cerebri ;     t.    medularis  ;    co- 
pula alba,  or  magna  cerebri :  great  com- 
missure of  the  brain ;  mesolobe. 


3  Facies,   or   superficies   superior,  or 
libera. 

4  Strise,  or  chordae  transversales  Wil- 
lisii. 

5  Raphe" ;  r.  externa ;  linea,  or  chorda 
longitudinalis. 

6  Striae    longitudinales    Lancisii,    in- 
ternse,  or  liberae  ;  nerves  of  Lancisi. 


520  THE   NERVOUS   SYSTEM. 

the  corpus  callosum  is  observed  to  be  a  thick  layer  of  white  substance 
passing  beneath  an  arching  convolution  of  each  cerebral  hemisphere. 
Its  anterior  part1  appears  doubled  on  itself  producing  a  thick  fold,  the 


FIG.  328. 


SECTION  OF  THE  BRAIN  ALONG  THE  GP.EVT  LONGITUDINAL  FISSURE.  1,  medulla  oblongata;  2,  pons;  3,  crus 
of  the  cerebrum;  4,  arborescent  appearance  in  section  of  the  fundamental  portion  of  the  cerebellum;  5, 
left  hemisphere  of  the  cerebellum;  6,  inner  surface  of  the  left  hemisphere  of  the  cerebrum;  7,  corpus 
rallosum;  8.  pellucid  septum;  9,  fornix;  10,  anterior  crus  of  the  fornix  descending  to  join  the  correspond- 
ing mammillary  eminence;  11,  fissure  through  which  the  interposed  vellum  12  is  introduced  into  the 
third  ventricle;  13,  pineal  gland;  14,  its  peduncle;  15,  rests  on  the  thalamus  within  the  third  ventricle; 
16,  posterior  commissure  of  the  latter;  17,  middle  commissure;  18,  anterior  commissure;  19,  foramen  of 
communication  between  the  third  and  lateral  ventricles ;  20,  optic  nerve;  21,  pituitary  body ;  22.  infun- 
dibulum;  23,  mammillary  eminence;  24,  oculo-motor  nerve;  25,  posterior  perforated  space;  26,  fourth 
ventricle;  27,  valve  of  the  brain;  28,  quadrigeminal  body;  29,  entrance  from  the  third  to  the  fourth  ven- 
tricle ;  30,  31, 32,  anterior,  middle,  aud  posterior  lobes  of  the  cerebrum. 

under  portion2  of  which  becomes  continuous  with  a  thin  lamina3  curving 
downward  to  the  optic  commissure,  and  closing  the  front  of  the  third 
ventricle.  The  posterior  part* is  seen  to  reach  the  base  of  the  cerebrum, 
just  above  the  position  of  the  quadrigeminal  body  and  the  most  promi- 
nent portion  of  the  cerebellum. 

In  structure  the  corpus  callosum  consists  of  a  thick  stratum  of  nerve 
fibres  diverging  through  the  white  substance  of  the  cerebral  hemispheres 
to  their  cortical  gray  substance. 

1  Genu  corporis  callosi.  3  Lamina  genu ;  lamina  cinerea  et  pe- 

2  Rostrum    corporis    callosi;    apex       dunculi  corporis  callosi. 

genu.  4  Splenium,  or  tuber  corporis  callosi. 


THE   NERVOUS   SYSTEM.  521 

FORNIX. 

Continuous  with  the  back  part  of  the  corpus  callosum,  and  arching 
forward  beneath  nearly  to  its  anterior  part,  is  a  thin  layer  of  white  sub- 
stance, the  fornix.1  Viewed  from  above  or  below  it  is  triangular.  Its 
upper  surface  along  the  middle  is  continuous  with  the  corpus  callosum 
and  pellucid  septum,  and  on  each  side  forms  part  of  the  floor  of  the 
lateral  ventricles.  Its  lower  vaulted  surface2  is  longitudinally  and  trans- 
versely striated,  and  forms  the  roof  of  the  third  ventricle. 

The  apex  of  the  fornix  divides  into  two  portions,  its  anterior  crura,3 
which  descend  with  a  slight  divergence  to  the  mammillary  eminences. 
The  basal  angles  are  prolonged,  as  its  posterior  crura,4  into  the  middle 
horns  of  the  lateral  ventricles,  and  become  continuous  with  the  fimbri- 
ated  body. 

PELLUCID    SEPTUM. 

The  interval  between  the  corpus  callosum  and  fornix,  in  the  median 
line  of  the  brain,  is  occupied  by  the  pellucid  septum,5  a  thin  partition 
of  nerve  substance  separating  the  lateral  ventricles.  It  includes  a  nar- 
row cavity  or  fissure,  the  fifth  ventricle,6  which  is  closed  at  all  points, 
and  is  lined  with  a  delicate  serous  membrane. 

The  pellucid  septum  is  composed  of  gray  substance  on  its  exterior 
surface,  and  of  white  substance  on  the  surface  next  the  fifth  ventricle. 

LATERAL   VENTRICLES. 

Beneath  the  corpus  callosum  on  each  side  is  a  cavity  with  prolonga- 
tions extending  into  the  three  lobes  of  the  cerebral  hemispheres.  The 
cavities  are  the  lateral  ventricles;7  the  prolongations  are  named  the 
horns.8 

1  Fornix    cerebri,  trilateralis,   or  tri-  5   Septum    pellucidum,    or   lucidum ; 
cuspidalis  ;   arcus  medullaris  ;  camera;  diaphragma  cerebri;     d.  ventriculorum 
cornix ;    corpus  psalloides ;    c.  camera-  lateralium ;    speculum ;    corpus    specu- 
tum  ;  trigonum  cerebrale  ;  testudo ;  com-  lare ;  mediastinum  ;  septum  medium  ;  s. 
munionis  cerebris.  tenue  ;    tympanum  ;    septum   medullare 

2  Lyra ;    psalterium  ;  corpus  psalloi-       triangulare. 

deum;  lamina  medullaris ;  1.  triangularis;  6   Ventriculus    quintus  ;    ventriculus, 

membrana  medullaris  inter  crura  poste-  camera,  or  sinus  septi  pellucidi ;   inci- 

riora  fornicis.  sura   septi ;    cavitas  Vieussenii,  Sylvii, 

3  Crura  or  cornua  anteriora  fornicis ;  Duncani,  prima,  or  quinta. 

cornua  fornicis  ;   columnae  fornicis  ;  an-  7  Ventriculi  laterales  ;  v.  anteriores  ; 

terior  pillars  or  pillar;  crus,  or  columna  v.  magni;  v.  majores;  v.  priores;  v.  su- 

fornicis.  periores ;  v.  tricornes  ;  sinus  anteriores. 

4  Crura  posteriora  fornicis ;  crura  for-  8  Cornua;    c.  laterales  ;    partes   late- 
nicis ;  posterior  pillars.  rales. 


522 


THE   NERVOUS   SYSTEM. 


Each  lateral  ventricle  has  for  its 
FIG.  329. 


TRANSVERSE  SECTION  OF  THE  CEREBRAL  HEMI- 
SPHERES, THE  CORPUS  CALLOSUM  REMOVED,  AND  THE 
LATERAL  VENTRICLES  EXPOSED.  1,  white  substance 
of  the  interior  of  the  cerebral  hemispheres;  2, 
gray  substance  of  the  exterior  convoluted  surface ; 
3,  4,  anterior  and  posterior  extremities  of  the  cor- 
pus callosum;  5,  anterior  horn  of  the  left  lateral 
ventricle ;  6,  middle  or  descending  horn ;  7,  poste- 
rior horn;  8,  striated  body;  9,  pellucid  septum; 
10,  fifth  ventricle;  11,  fomix;  12,  posterior  crus  of 
the  fornix;  13,  attachment  of  the  fornix  to  the 
under  part  of  the  corpus  callosum ;  14,  hippocam- 
pus; 15,  fimbriated  body;  16,  ergot;  17,  semicir- 
cular line;  18,  choroid  plexus;  19,  edge  of  the 
thalamus. 


roof1  the  corpus  callosum,  its  floor 
the  fornix,  its  inner  wall  the  pellu- 
cid septum,  and  its  outer  wall  the 
striated  body. 

The  anterior  horn2  of  the  lat- 
eral ventricle,  less  conspicuous 
than  the  others,  is  simply  the  ex- 
tension of  the  cavity  around  the 
anterior  extremity  of  the  striated 
body. 

The  middle  horn3  curves  down- 
ward into  the  middle  cerebral  lobe. 
From  the  inner  part  of  its  floor 
projects  a  thick  convex  ridge,  in- 
dented at  its  lower  end,*  and  named 
the  hippocam/pus,5  The  upper 
border  of  the  ridge  is  provided 
with  a  white  band,  named  the  fim- 
briated body,6  which  is  continuous 
with  the  posterior  crus  of  the  for- 
nix. 

The  hippocampus  is  composed 
of  white  substance7  on  the  sur- 
face, of  gray  substance  within, 
and  the  latter  appears  superficially 
as  a  dentated  band8  on  the  inner 
or  concave  side  of  the  hippocam- 
pus. 

The  posterior  horn9  curves  in- 
wardly as  it  passes  into  the  pos- 


1  Tegumentum  cellse  lateralis;  t.  ven- 
triculi  lateralis. 

2  Cornu  anterius. 

3  Cornu  medium,  inferius,  descendens, 
magnum,  or  laterale ;  sinus  inferior  hip- 
pocampi ;  s.  cornu  Ammonis ;  ventricu- 
lus  inferior  hippocampi ;  v.  bombycinus. 

4  Digiti  cornu  Ammonis  ;  colliculi  fissi 
interni ;  uncus  ;  pes  hippocampi. 

5  Hippocampus  major;  pes  hippocam- 
pi;   p.  h.  major;    cornu  Ammonis;    c. 
arietis ;  vermis,  or  appendix   bombyci- 


nus; bombyx;  processus  cerebri  late- 
ralis ;  protuberantia  cylindroides ;  pes 
hippopotami  major. 

6  Fimbria,  or  tsenia  hippocampi;  lira- 
bus,  or  corpus  fimbriatum ;  c.  f.  Sylvii. 

7  Lamina  medullaris  superficialis  cor- 
nu Ammonis. 

8  Fascia  dentata ;  margo  denticulatus 
Tarini. 

9  Cornu  posterius  ;  cavitas   digitalis ; 
c.  ancyroidea ;  diverticulum. 


THE   NERVOUS   SYSTEM.  523 

terior  cerebral  lobe.     From  its  inner  side  projects  a  white,  spur-like 
ridge,  named  the  ergot.1 

The  lateral  ventricles  communicate  with  each  other  and  with  the  third 
ventricle  by  a  foramen2  beneath  the  anterior  crura  of  the  fornix.  In  all 
other  positions  they  are  closed,  and  are  lined  throughout  with  a  delicate 
serous  membrane. 

CORPORA   STRIATA,  OR    STRIATED    BODIES. 

Projecting  into  each  lateral  ventricle  from  the  outer  wall  is  a  half- 
pyriform  prominence,  named,  from  its  appearance  in  section,  the  cor'pus 
stria'tum,  or  striated  body,3  Its  larger  portion4  is  anterior,  and  its 
narrower  portion5  curves  backward  to  the  outer  side  of  the  thalamus. 
Some  depth  from  the  ventricular  surface  it  is  composed  of  gray  substance,6 
beneath  which  is  a  layer  of  white  substance,7  succeeded  by  a  lenticular 
nucleus8  of  gray  substance.  The  latter  is  penetrated  by  the  diverging 
fibres  of  the  cerebral  crus,  giving  to  it  in  section  a  striated  appearance. 
Below  the  fore  part  of  the  lenticular  nucleus  is  a  smaller  accumulation 
of  gray  substance,9  and  to  its  outer  side  is  another  collection.10 

On  the  floor  of  each  lateral  ventricle  is  a  remarkable  vascular  append- 
age of  the  pia  mater,  named  the  choroid  plexus,  This  extends  from 
the  foramen  beneath  the  anterior  crura  of  the  fornix  along  the  side  of 
the  latter,  and  descends  to  the  bottom  of  the  middle  horn  of  the  lateral 
ventricle.  It  is  continuous  beneath  the  fornix  with  the  interposed  velum 
of  the  pia  mater,  and  is  separated  from  the  cavity  of  the  lateral  ventricle 
by  its  lining  membrane. 

THIRD    VENTRICLE. 

Beneath  the  fornix  is  the  third  ventricle11  of  the  brain.  This  is  a 
narrow  triangular  cavity,  with  its  apex  forward  and  its  base  correspond- 
ing with  the  fissure  between  the  posterior  border  of  the  corpus  callosum 

1  Hippocampus    minor ;     calcar ;    c.       rum  ethmoidalium ;  apices  crurum  me- 
avis  ;  unguis ;  u.  avis ;  u.  Halleri ;  ocrea;       dullae  oblongatae. 

pes  hippocampi  minor ;  eminentia  minor  4  Caput. 
digitata;  e.  unciformis ;  ocrea;  collicu-  5  Cauda. 
lus.  6  Nucleus  caudatus ;  n.  intraventricu- 

2  Foramen  of  Monro  ;    f.  Monroi ;  f.  laris. 

anterius ;  vulva.  ?  Capsula  medullaris  nuclei  lentifor- 

3  PI. :  corpora  striata;  eminentise  stria-       mis  ;  capsula  externa. 

tae;  e.  pyriformes;  e.  similes  coxis  hu-          8  Nucleus  lentiformis;    n.  extraven- 

mani ;  e.  lenticulares  ;  prominentiae  len-  tricularis. 

tiformes ;    apices   medullse    oblongatae ;  9  Nucleus  amygdalae. 

processus  anteriores  medullae  oblonga-          10  Claustrum  ;  nucleus  tseniseformis. 

tae  ;   ganglia  magna  superiora  cerebri ;          n  Ventriculus  tertius  ;  v.  medius  cere- 

g.  cerebralia  anteriora  ;  colliculi  nervo-  bri. 


524  THE   NERVOUS   SYSTEM. 

and  the  quadrigeminal  body.  Its  fore  part  is  closed  by  the  anterior 
descending  portion  of  the  corpus  callosum.  Its  floor  is  formed  in  suc- 
cession from  before  backward  by  the  optic  commissure,  infundibulum,1 
mammillary  eminences,  posterior  perforated  space,  and  cerebral  crura. 
Behind  the  latter  and  beneath  the  quadrigeminal  body  it  communicates2 
with  the  fourth  ventricle  by  a  narrow  passage,3  the  sides  of  which  are 
coated  with  gray  substance.4  As  previously  mentioned,  beneath  the 
anterior  crura  of  the  fornix  it  opens  on  each  side  into  the  lateral  ven- 
tricles. 

At  the  fissure,5  between  the  posterior  border  of  the  corpus  callosum 
and  the  cerebellum,  a  process  of  pia  mater,  the  interposed  velum,6  is 
introduced  along  the  under  surface  of  the  fornix,  which  forms  the  vaulted 
roof  of  the  third  ventricle. 

THALAMI. 

The  outer  walls  of  the  third  ventricle  are  formed  by  a  large,  oval 
prominence,  the  thal'amus,7  which  is  supported  on  the  inner  side  of  the 
diverging  cerebral  crus.  Its  ventricular  surface,  for  the  most  part,  is 
composed  of  white  substance,8  but  on  the  inner  side  exhibits  some  gray 
substance.  Its  interior  is  composed  of  mingled  white  and  gray  sub- 
stance.9 

In  front  and  to  the  outer  side  the  thalamus  is  separated  from  the  stri- 
ated body  by  a  narrow  semicircular  band10  of  white  substance.  The 
anterior  and  posterior  more  prominent  portions  of  the  thalamus  are 
named  its  tubercles.11  Beneath  the  posterior  tubercle  are  two  convex 
white  eminences,  the  genic'ulate  bodies,12  which  give  partial  origin  to 
the  optic  tracts. 

1  Aditus  ad  infundibulum.  nse  cerebri ;  corpora  striata  superna  pos- 

2  Aditus  ad  aquaeductum  Sylvii ;  in-  teriora ;   c.  s.  posteriora  interna ;    colli- 
troitus.  culi   nervorum    opticorum ;    capita,    or 

3  Iter  etertio  adquartum  ventriculum;  crura  medullse  oblongatae;  juga  crurum 
aquaeductus  Sylvii;  fistula  sacra;  ven-  medullarium ;   secundum  par  tuberculo- 
triculus  subter  nates  et  testes ;  transi-  rum  ;    secunda  sectio  crurum  medulla  - 
tus    ad   ventriculum    quartum;      aquae  rium. 

emissorium ;  canalis  medianus  ;   incile,  8  Stratum  zonale. 

or  canalis   tuberculorum ;    c.  corporum  9  Nuclei  cinerei. 

quadrigeminorum.  10  Toenia  semicircularis ;  t.  terminalis; 

4  Subsfantia  feruginea  superior.  lamina  cornea ;  centrum  geminum  semi- 

5  Transverse  fissure  of  the  cerebrum.  circulare  ;  stria  cornea.    In  part :  acies, 

6  Velum  interpositum  ;  tela  choroidea.  flabellum,  and  penicillus. 

7  Optic  thalamus  ;  pi. :  thalami  nervo-  u  Tuberculum    superius  anterius  and 
rum  opticorum ;  ganglia  magna  inferiora  t.  s.  posterius,  or  pulvinar. 

cerebri ;  g.  cerebri  media  ;  g.  c.  postica ;  li  Corpus  geniculatum  internum  and 
protuberantiae  striatse ;  eminentiae  mag-  c  g.  externum  ;  corpora  geniculata. 


THE  NERVOUS   SYSTEM. 


525 


QUADRIGEMINAL    BODY. 

At  the  back  part  of  the  third  ventricle  is  situated  a  quadrate,  white 
mass,  divided  on  its  upper  surface  by  a  crucial  gutter1  into  four  emi- 

FIG.  330. 


STRIATED  BODIES,  THALAMI,  QUADRIGEMIXAL  BODY,  AXD  CEREBELLUM.  1,  quadrigeminal  body;  2,  valve  of 
the  brain  ;  3,  superior  peduncle  of  the  cerebellum;  4,  superior  portion  of  the  middle  peduncle;  5,  supe- 
rior portion  of  the  crus  of  the  cerebrum;  6,  posterior  tubercle  of  the  thalamus;  7,  anterior  tubercle;  8, 
fundamental  portion  of  the  cerebellum  ;  9,  process  of  gray  substance  Besting  on  the  valve  of  the  brain ; 
10,  posterior  commissure  of  the  third  ventricle;  11,  middle  commissure;  12,  anterior  commissure;  13, 
pineal  gland  turned  forward;  14,  its  peduncle;  15,  thalaimis ;  16,  hemispheres  of  the  cerebellum;  17, 
dentated  body;  18,  semicircular  line;  19,  vein  of  the  striated  body;  20,  anterior  crura  of  the  fornix;  21, 
striated  body;  22,  fifth  ventricle  between  the  layers  of  the  pellucid  septum. 

nences,  from  \whence  it  derives  the  name  of  quadrigem'inal  body  or 
bodies.2  It  extends  obliquely  from  the  thalami  toward  the  cerebellum, 
with  which  it  is  connected  by  the  superior  peduncles.  At  the  sides  it  is 


1  Sulcus  longitudinalis  et  s.  transver- 
sus  corporum  qTiadrigeminorum. 

2  Corpora,  or  tubercula  quadrigemina; 
c.  bigemina  ;  c.  anteriores  ;  protuberan- 
tiae  ;  processus  natiformes  et  testiformes; 
tubercula ;    t.  anteriora   et  posteriora ; 


prominent  ias ;  p.  orbiculares  ;  p.  ence- 
phalali ;  nates  et  testes ;  prominentise, 
eminently,  or  corpora  superiores  et  in- 
feriores,  majores  et  minores,  or  nati- 
formes et  testiformes ;  pons  Sylvii. 


526  THE   NERVOUS   SYSTEM. 

attached  to  the  thalami  and  geniculate  bodies ;  and  by  means  of  a  band1 
of  white  substance  joins  the  back  part  of  the  pons  between  the  crura  of 
the  cerebrum  and  cerebellum.  Between  it  and  the  posterior  border  of 
the  corpus  callosum  is  the  fissure  through  which  the  interposed  velum  of 
the  pia  mater  is  introduced  along  the  roof  of  the  third  ventricle. 
Beneath  it  is  the  entrance  from  the  latter  to  the  fourth  ventricle. 
« 

PINEAL   GLAND. 

Upon  the  anterior  pair  of  eminences  of  the  quadrigeminal  body  there 
reposes  a  small  cone  of  gray  substance,  named  the  pine'al  gland.2  It  is 
remarkable  for  containing  a  quantity  of  sand-like  grains,3  having  nearly 
the  same  composition  as  bone  earth.  From  the  front  of  the  pineal  gland 
a  pair  of  narrow  tracts  of  white  matter,  named  its  pedun'cles,4  diverge, 
like  the  prongs  of  a  fork,  to  the  inner  sides  of  the  thalami. 

COMMISSURES   OF   THE   THIRD   VENTRICLE. 

The  anterior  com'missure5  appears  as  a  small  transverse  cylinder  of 
white  substance  at  the  front  part  of  the  third  ventricle,  between  the 
anterior  crura  of  the  fornix  and  the  descending  portion  of  the  corpus 
callosum.  It  is  a  cord  of  white  nerve  fibres  extending  through  the 
lower  part  of  the  striated  bodies  into  the  cerebral  hemispheres. 

The  middle  commissure6  is  a  rounded  isthmus  of  gray  substance  con- 
necting the  thalami  across  the  centre  of  the  third  ventricle. 

The  posterior  commissure7  is  a  thin  lamina  of  white  substance  ex- 
tended between  the  back  part  of  the  thalami,  and  connecting  the  quadri- 
geminal body  with  the  pineal  gland. 

THE  CEREBELLUM. 

The  Cerebellum8  forms  about  one-eighth  of  the  bulk  of  the  brain, 
and  occupies  the  posterior  fossae  of  the  cranial  cavity,  beneath  the  ten- 

1  Lemniscus ;  fillet ;  laqueus ;  fascicu-  *  Pedunculi  conarii ;  striae,  or  taeniee 
lus    triangularis    lateralis ;    ribbon    of      medullares ;  habenula ;  reins. 

Reil.  5  Commissura  anterior. 

2  Glandula  pinealis;  conarium;  pinus;  6  Commissura  media  ;  c.  mollis ;  chor- 
penis ;  cerebral  epiphysis  ;    corpus  co-  dae  Willisii ;  unio  thalamoruni  nervorum 
noides;  c.  turbinatum;    turbo  cerebri;  opticorum. 

virga.  7  Commissura  posterior. 

3  Cerebral    sand;    acervulus  cerebri;  8  Cerebrum  parvum ;  c.  posterius ;  ap- 
concrementa  pinealia;  sabulous  matter;  pendix  ad  cerebrum ;  encranion;   epen- 
brain  sand  ;  pineal  sand ;  sabulum  co-  cranis ;    parencephalum  ;    encephalium ; 
narii ;  lapilli  glandulae  pinealis.  micrencephalum ;  encephalus  opistliius ; 

little  brain ;  after  brain. 


THE  NERVOUS  SYSTEM.  527 

torium,  which  separates  it  from  the  posterior  lobes  of  the  cerebrum. 
Like  the  latter,  it  consists  of  two  lateral  portions,  named  hemispheres,1 
which  are  separated  behind  and  below  by  a  wide,  deep  groove,  named 
the  valley.2 

The  hemispheres  are  associated  by  an  intermediate  or  fundamental 
portion,3  which  is  not  distinctly  evident  above,  but  appears  at  the  bottom 
of  the  valley  as  a  thick,  worm-like  ridge,  whence  it  received  the  name 
of  the  verm'iform  process.4 

The  superior  cerebellar  surface5  is  moderately  convex,  is  most  prom- 
inent at  its  anterior  portion,6  and  inclines  from  the  median  line  of  union7 
of  the  hemispheres  to  their  lateral  border.  The  lower  and  outer  sur- 
faces8 are  prominently  convex. 

The  exterior  of  the  cerebellum  presents  the  same  gray  color  as  that 
of  the  cerebrum,  and  is  divided  by  numerous  fissures9  into  nearly  par- 
allel laminae,10  having  a  general  transverse  direction. 

When  the  constitution  of  the  hemispheres  is  examined,  it  is  found 
that  each  consists  of  an  interior  prismoid  trunk11  of  white  substance, 
from  the  sides  of  which  emanate  about  a  dozen  broad,  thin,  divergent 
laminge  of  the  same  material.  These  divide  into  a  second  series  of 
thinner  laminae,  which  in  many  cases  subdivide.  Around  the  laminar 
divisions  of  white  substance  the  cortical  gray  substance  of  the  cerebellum 
is  folded,  the  intervals  of  the  folds  corresponding  with  fissures  of  the 
cerebellar  surface.  In  consequence  of  this  arrangement,  a  vertical  sec- 
tion of  the  hemispheres  exhibits  an  arborescent  appearance,12  while  a 
transverse  section  simply  presents  a  broad  surface  of  the  medullary 
white  substance  bordered  by  gray  substance. 

The  fundamental  portion  of  the  cerebellum  exhibits  the  same  arrange- 
ment of  structure  as  the  hemispheres,  and  differs  only  in  accordance 
with  the  comparative  size  of  the  part. 

At  the  anterior  extremity  of  the  valley,  the  hemispheres  form  a  pair 
of  rounded  eminences,  including  between  them  a  more  prominent  por- 


1  Hemisphseria  cerebelli ;   pontes  late-  6  Culmen  ;  monticulus. 

rales.  *  Monticulus ;  superior  vermiform  pro- 

2  Vallis ;  vallecula ;  scissura  cerebelli  cess ;    vermis   superior ;     protuberantia 
longitudinalis.  vermiformis  superior. 

3  Ambitus  vermis  ;    vermiform    pro-  8  Superficies  cerebelli  inferior, 
cess.  9  £ulci. 

4  Inferior    vermiform    process ;    the  10  Gyri ;  convolutions ;  circonvolutions. 
worm;   vermis   inferior;   protuberantia  n  Stratum  medullare  ;  meditullium  la- 
vermiformis;    pyramid   of    Malacarne;  terale. 

pyramid,  uvula,  and  nodulus.  12  Arbor  vitae. 

5  Superficies  cerebelli  superior. 


528  THE   NERVOUS  SYSTEM. 

tion  of  the  vermiform  process,  which  together,  from  their  resemblance 
in  relative  position,  have  been  named  tonsils1  and  uvula,  Above  the 
tonsils  anteriorly,  and  separated  from  them  by  a  fissure2  proceeding 
from  the  cerebellar  crura  outwardly,  each  hemisphere  presents  the  pneu- 
mogas'tric  lobule,3  so  named  from  its  vicinity  to  the  corresponding 
nerve. 

DENTATED  BODY. 

Within  the  trunk  of  white  substance  of  each  hemisphere  of  the  cere- 
bellum there  is  a  plicated  pouch-like  layer4  of  gray  substance.  In  sec- 
tion this  appears  as  an  indented  nucleus  of  white  substance5  bordered  by 
gray  substance,  whence  its  name  of  the  dentated  body.6  The  gray  layer 
is  open  at  its  upper  and  inner  part,  in  which  position  the  nerve  fibres  of 
the  white  substance  gain  admission  to  its  interior  surface. 

CRURA   OF   THE   CEREBELLUM. 

At  the  base  of  the  brain,  the  pons  extends  laterally  as  a  pair  of 
cylindroid  processes  of  white  substance,  diverging  posteriorly,  and  enter- 
ing the  hemispheres  of  the  cerebellum.  These  processes  are  the  crura, 
or  middle  pedun/cles  of  the  cerebellum.7  They  are  longitudinally 
striated,  and  consist  of  large  bundles  of  nerve  fibres  proceeding  from 
the  pons  to  the  white  substance  of  the  cerebellar  hemispheres. 

Behind  the  crura  are  situated  the  superior  and  inferior  peduncles  of 
the  cerebellum. 

The  Superior  pedun'cles8  are  two  flattened,  cylindrical,  white  bands, 
ascending  obliquely  in  a  converging  manner  from  the  interior  white  sub- 
stance of  the  hemispheres  of  the  cerebellum  to  the  quadrigeminal  body. 
The  triangular  interval  of  these  peduncles,  and  the  fundamental  portion 
of  the  cerebellum,  is  closed  by  a  thin  lamina  of  white  matter,  incorrectly 

1  Tonsillae  ;  amygdalae  ;    lobi  medullae  ciliare ;    g.  cerebelli ;    substantia  rhom- 
oblongatae  ;  lobi  intern!  cerebelli.  boidea. 

2  Sulcus  horizontals  ;    s.  perpendicu-  7  Crura  cerebelli ;  c.  c.  ad  pontem;  c. 
laris  ;  s.  magnus  cerebelli.  media ;  c.  lateralia ;  c.  posteriora ;  bra- 

3Lobulinervi-pneumogastrici;  appen-  chia  pontis. 

dices lobulares  anteriores ;  flocculi;  sub-  8  Anterior  peduncles;  crura,  or  bra- 
peduncular  lobes.  chia  cerebelli  ad  corpora  quadrigemina ; 

4  Fascia  dentata  cinerea,  or  fimbriata.  crura   superiora  ;    c.  anteriora ;    c.  ad- 

5  Medulla  centralis,  or  ciliaris.  scendentia ;     commissura     cerebelli    et 

6  Corpus     dentatum,    denticulatum,  cerebri;  brachia  conjunctoria,  or  copu- 
rhomboideum,  ciliare,  or  mixtum;   nu-  lativa;    processus    cerebelli   ad    testes; 
cleus  dentatus,  rhomboidalis,  lenticula-  processus  ad  testes ;    columnae  valvulas 
tus,  fimbriatus,  or   centralis ;    ganglion  Vieussenii ;    oblique  intercerebral  com- 
missures. 


THE   NERVOUS  SYSTEM.  529 

named  the  valve  of  the  brain.1  This  so-called  valve  is  attached  at  all 
its  borders,  and  is  situated  over  the  fourth  ventricle.  Upon  its  upper 
surface  a  tongue-like  process2  of  gray  substance,  transversely  ridged,  is 
extended  from  the  cerebellum. 

The  Inferior  peduncles  of  the  cerebellum,3  smaller  than  the  others, 
are  two  narrow,  white  bands,  which  proceed  from  the  interior  of  the 
hemispheres,  and  descend  to  become  continuous  with  the  restiform  bodies 
of  the  medulla  oblongata. 

THE  PONS. 

The  Pons4  is  a  quadrate  white  body,  situated  back  of  the  middle  of 
the  base  of  the  cerebrum,  and  in  advance  of  the  cerebellum.  It  rests  on 
the  upper  part  of  the  basilar  process  of  the  occipital  bone,  and  the  de- 
clivity of  the  sphenoid  bone.  Its  under  surface  is  convex  and  trans- 
versely striated,5  and  its  anterior  and  posterior  borders  are  rounded. 
Along  the  median  line  of  the  under  surface  it  presents  a  shallow  groove,6 
which  accommodates  the  basilar  artery,  and  also  exhibits  small  perfora- 
tions transmitting  branches  of  the  latter. 

The  superficial- or  lower  portion  of  the  pons  is  composed  of  transverse 
nerve  fibres,  which  at  the  sides  diverge  as  the  crura  or  middle  peduncles 
of  the  cerebellum. 

The  association  of  the  hemispheres  of  the  cerebellum  through  its 
middle  peduncles  is  the  origin  of  the  name  pons,  signifying  a  bridge, 
though  the  term  is  extended  in  its  application  to  the  deeper  parts,  or 
those  within  the  superficial  portions  of  the  structure.  The  latter,  which 
constitutes  a  transverse  commissure  conjoining  the  hemispheres  of  the 
cerebellum,  depends  on  these  for  its  existence ;  and  therefore  in  birds, 
in  which  the  cerebellar  hemispheres  do  not  exist,  the  transverse  commis- 
sural  portion  of  the  pons  is  absent. 

1  Valvula  cerebelli ;  v.  Vieusseriii ;  v.  4  Pons  Varolii ;    p.  cerebelli ;    nodus 

Willisiana ;   v.  cerebri ;   v.  magna  cere-  encephali ;    n.    cerebri ;     protuberantia 

bri;  velum  medullare  anterius;  v.Vieus-  annularis  ;  p.  a.  Willisii ;  p.  basilaris; 

senii;  v.  interjectum  cerebelli;    v.  apo-  annular  protuberance;  processus,  emi- 

physi  vermiformi  obtentum;    lacunar  nentia,  or  prominentia  annularis ;  tuber 

ventriculi  quarti  superior.  annulare ;  corpus  annulare ;  commissura 

2Lingula;  linguetta  laminosa.  hemisphseriorum  cerebelli;  c.  cerebelli; 

3  Pedunculi  cerebelli  sensu  strictiori;  mesocephalon;  Varoli's  bridge;  cerebral 

crura  cerebelli  ad  medullam  oblongatam ;  protuberance. 

c.  c.  ad  medullam  spinalem ;  crura  infe-  ^  Sulci  transversi ;   s.  obliqui ;   s.  mi- 

riora ;  c.  posteriora.  nores  pontis. 

6  Sulcus  basilaris. 
34 


530  THE   NERVOUS   SYSTEM. 

From  the  front  of  the  pons,  the  crura  of  the  cerebrum  appear  to 
emerge,  and  this  is  found  actually  to  be  the  case  on  removal  of  the 
superficial  portion  of  the  pons ;  for  within  this,  longitudinal  fasciculi  of 
fibres,  intermingled  with  gray  matter,  extend  from  the  medulla  oblongata 
upward  to  become  continuous  with  the  cerebral  crura. 


THE  MEDULLA  OBLONGATA. 

The  Medulla  oblonga'ta1  is  the  smallest  of  the  four  divisions  of  the 
brain,  and  is  a  white,  pyriform  body,  situated  in  front  of  the  cerebellum, 
and  extending  from  the  pons  to  the  spinal  cord,  with  which  it  is  con- 
tinuous. It  is  a  little  over  an  inch  in  length,  and  rests  in  the  groove  of 
the  basilar  process  of  the  occipital  bone.  It  is  divided  into  two  lateral 
portions  by  an  anterior  and  a  posterior  median  fissure,  continuous  below 
with  the  corresponding  fissures  of  the  spinal  cord. 

The  medulla  oblongata  is  further  divided  on  each  side  into  the  pyram- 
idal, olivary,  and  restiform  bodies,  and  the  posterior  pyramids. 

The  Pyram'idal  bodies2  appear  on  each  side  of  the  anterior  median 
fissure  as  a  club-shaped,  white  mass,  continuous  below  with  the  anterior 
and  lateral  columns  of  the  spinal  cord.  Their  upper  and  thicker  ex- 
tremity is  rounded,  and  is  connected  with  the  pons. 

At  the  lower  part  of  the  median  fissure  portions  of  the  white  sub- 
stance of  the  pyramidal  bodies  cross  from  side  to  side,  producing  the 
decussation  of  the  pyramids.3 

In  structure  the  pyramidal  bodies  are  three-sided  prismatic  bundles  of 
nerve  fibres,  ascending  from  the  anterior  and  lateral  columns  of  the 
spinal  cord  to  the  pons.  The  inner  fibres  ascend  from  the  lateral  columns 
of-  the  cord,  and  cross  to  the  opposite  side,  thus  producing  the  decussa- 
tion above  mentioned ;  the  lateral  fibres  ascend  from  the  anterior  col- 
umns of  the  spinal  cord  of  the  same  side. 

The  Ol'ivary  bodies4  appear  as  oval,  white  prominences  to  the  outer 
side  of  the  pyramidal  bodies.  They  are  composed  of  white  substajice, 
and  contain  a  plicated,  pouch-like  layer  of  gray  substance.  In  section 

1  Bulbusrachidicus;  caudex  encephali  s  Decussatio  pyramidum;  decussation 
communis;    medulla   respiratoria ;    ob-       of  Mistichelli. 

long    medulla ;     cerebrum   elongatum ;  4  Corpora  olivaria ;    eminentiee   oliva- 

centrum  vitale.  res ;    e.  ovales ;    e.  o.  laterales ;   olivse  ; 

2  Corpora  pyramidalia;    c.  p.  anteri-  corpora  ovata,  or  semiovalia;  funiculi, 
ora ;  c.  p.  interna ;  eminentise  pyramid-  or  fasciculi  ovales. 

ales ;  e.  oblongae ;  e.  medianae  internes. 


THE   NERVOUS   SYSTEM.  531 

the  latter  gives  the  central  mass  of  the  olivary  bodies  the  appearance  of 
an  indented  oval  nucleus,  whence  its  name  of  the  dentated  body.  An 
additional  small  accumulation  of  gray  substance  within  the  olivary 
bodies,  distinct  from  the  former,  is  named  the  accessory  olivary  nucleus. 
The  white  substance  of  the  olivary  bodies  is  continuous  with  that  of 
the  anterior  columns  of  the  spinal  cord,  and  forms  a  fasciculus,  which 
may  be  traced  through  the  pons  to  the  crura  of  the  cerebrum  and  the 
quadrigeminal  body. 

The  Res'tiform  bodies,1  situated  to  the  outer  side,  posteriorly,  of  the 
olivary  bodies,  ascend  from  the  spinal  cord  in  a  divergent  manner,  and 
become  continuous  with  the  inferior  peduncles  of  the  cerebellum.  They 
are  composed  of  white  substance  continuous  with  that  of  the  spinal 
cord,  and  contain  some  gray  substance2  continuous  with  the  posterior 
horns  of  the  latter'. 

The  Posterior  pyramids3  are  situated  behind  the  preceding  bodies,  on 
each  side  of  the  posterior  median  fissure,  and  diverge  at  the  sides  of  the 
fourth  ventricle.  They  consist  of  two  narrow  fasciculi  of  white  sub- 
stance, continuous  with  the  posterior  median  columns  of  the  spinal  cord, 
and  appear  to  merge  in  the  inferior  peduncles  of  the  cerebellum. 

At  the  sides  of  the  medulla  oblongata,  below  the  olivary  bodies,  or 
even  crossing  their  lower  part,  there  usually  exist  some  arching  fibres 
connecting  the  pyramidal  and  restiform  bodies,  and  named  arciform 
fibres.4  Other  fibres  also  pass  transversely  from  before  backward,  within 
the  median  fissures  of  the  medulla  oblongata,  and  are  named  septal 
fibres. 

FOURTH   VENTRICLE. 

The  triangular  space  included  between  the  medulla  oblongata  and 
pons  in  front,  and  the  cerebellum  behind,  is  called  the  fourth  ventricle.5 


1  Corpora   restiformia ;    pyramides  3  Fasciculi  graciles. 

laterales ;    fasciculi,    or  funiculi  pyra-  4  Fibrae  transversae  arciformes ;  stra- 

midales;  fasciculi  laterales  et  cuneati;  turn  zonale  medullse  oblongatae ;  pontl- 

corpora   pyramidalia    posteriora;    pro-  culus. 

cessus  a  cerebelli  ad  medullam  oblonga-  5  Ventriculus  quartus ;  v.  Arantii ;  v. 

turn;  peduncles  of  the  medulla  oblongata;  calami- scriptorii ;    v.  rhomboidalis ;    v. 

inferior  peduncles  of  the  cerebellum.  cerebelli ;  ventricle  of  the  cerebellum. 

2  Nucleus,  or  corpus  cinereus ;   par- 
tially the  tubercula  cinerea  of  Rolando. 


532  THE  NERVOUS   SYSTEM. 

It  communicates,  by  a  narrow  passage1  ascending  beneath  the  quadri- 
geminal  body,  with  the  third  ventricle,  and  is  lined  with  a  delicate  serous 
membrane,  continuous  with  that  of  the  latter  cavity,  and  opening  below 
into  the  subarachnoid  space  of  the  spinal  cord. 

The  posterior  sloping  roof  of  the  fourth  ventricle  is  formed  by  the 
superior  peduncles  of  the  cerebellum,  and  the  intervening  "valve"  of 
the  brain.  Its  sides,  posteriorly,  are  formed  by  the  inferior  peduncles 
of  the  cerebellum. 

The  anterior  part,  or  floor  of  the  fourth  ventricle,2  is  formed  by  the 
back  of  the  medulla  oblongata  and  pons.  It  is  lozenge  shaped  in  out- 
line, and  is  bounded  laterally  above  by  the  superior  peduncles  of  the 
cerebellum ;  below  by  the  inferior  peduncles,  the  restiform  bodies,  and 
posterior  pyramids.  The  sides  of  the  floor  incline  to  the  posterior  me- 
dian fissure,3  which  is  continuous  below  with  that  of  the  spinal  cord,  and 
becomes  obsolete  above. 

The  surface  of  the  floor  is  rendered  uneven  by  several  slight  convex 
eminences,4  and  is  invested  with  a  layer  of  gray  substance5  continuous 
with  that  of  the  spinal  cord.  On  each  side  it  is  crossed  by  a  series  of 
transverse  white  lines6  which  are  connected  with  the  origin  of  the  audit- 
ory nerves. 

At  the  lower  angle7  of  the  floor  is  a  small  pit,8  which  is  the  upper  ex- 
tremity of  a  canal9  existing  during  foetal  life  along  the  centre  of  the 
spinal  cord. 

The  lower  portion  of  the  fourth  ventricle  is  closed  by  the  arachnoid 
membrane,  but,  as  previously  indicated,  it  communicates  with  the  sub- 
arachnoid  space  of  the  spinal  cord. 

1  Meat  us     conjunctorius    ventriculi       nentise  cuneiformes  cinereae ;  alas  cine- 
quarti  ettertiimedii;  aquseductus  Sylvii;       reae,  or  folia  cinerea  lanceolata. 

iter  e  tertio  ad  quartam  ventriculam.  5  Comprising   the   substantia   cinerea 

2  Sinus,  fovea,  fossa,  or  cavitas  rhom-  ochracea ;   locus  cinereus,  or  cceruleus, 
boidalis ;    scrobs,    or    fovea    ventriculi  or  substantia  ferruginea ;  and  the  fasci- 
quarti;    area,   or   semicanalis  medullae  olae  cinereae. 

oblongatae.  6  Striae,  toaniae,  or  fibrae  medullares, 

3  Sulcus,  or  fissura  longitudinalis ;  s.  or  acusticae;  fasciculi  et  fibrillge  filiforines 
or  f.  medius  fossas  rhomboidalis.  nervi  acustici. 

4  These   comprise — 1,  the  eminentiae  7  Calamus  scriptorius. 
teretes,  semiteretes,  perpendiculares,  or  8  Ventriculus  Arantii. 
longitudinales ;  funiculi,  or  fasciculi  te-  9  Canalis  medullae  spinalis. 
retes,  or  the  corpora  teretia;  2,  the  emi- 


THE   NERVOUS   SYSTEM.  533 


THE  SPINAL  CORD. 

The  Spinal  cord,1  the  centre  of  excito-motor  impulses,  with  its  mem- 
branes, occupies  the  vertebral  canal.  It  is  continuous  with  the  medulla 
oblongata,  and  extends  from  the  occipital  foramen  to  the  lower  part  of 
the  first  lumbar  vertebra. 

In  the  embryo  the  spinal  cord  corresponds  in  length  with  the  verte- 
bral column,  but  subsequent  to  the  third  month  the  latter  grows  more 
rapidly  than  the  former,  so  that  at  birth  the  cord  extends  only  as  far  as 
the  third  lumbar  vertebra. 

The  length  of  the  spinal  cord  of  the  adult  is  from  fifteen  to  eighteen 
inches,  and  its  weight  about  an  ounce  and  a  half  avoirdupois.  In  gen- 
eral form  it  is  cylindrical,  compressed  from  before  backward,  and  it  varies 
in  diameter  in  different  positions.  In  the  region  of  the  neck  it  presents 
the  cervical  enlargement2  extending  from  about  the  third  cervical  to 
the  first  dorsal  vertebra.  Below  this  position  it  is  of  nearly  uniform 
diameter,  until  it  forms  the  lumbar  enlargement,3  which  is  opposite  the 
last  dorsal  vertebra,  and  subsequently  it  tapers  to  a  conical  point.4 

The  cervical  and  lumbar  enlargements  correspond  with  the  large  nerves 
connected  with  these  portions  of  the  spinal  cord.  Where  other  nerves 
emanate  from  the  latter,  it  exhibits  slight  enlargements,  which  give  to 
the  sides  of  the  cord  a  somewhat  undulating  appearance. 

Exteriorly  the  spinal  cord  is  composed  of  white  nerve  substance ;  in- 
teriorly, of  gray  substance — the  former  being  the  more  abundant,  espe- 
cially in  the  cervical  region. 

In  front  and  behind,  the  spinal  cord  is  divided  by  fissures  into  lateral 
symmetrical  halves. 

The  anterior  median  fissure5  penetrates  about  one-third  the  thickness 
of  the  cord,  but  becomes  deeper  toward  its  lower  extremity.  The  white 
substance  at  its  bottom  associating  the  two  sides  of  the  cord  is  named 
the  anterior  or  white  commissure.6 

The  posterior  median  fissure,7  narrower,  and  for  the  most  part  deeper 
than  the  anterior,  becomes  shallower  toward  its  lower  end. 

1  Medulla   spinalis :    spinal   marrow ;  3  Intumescentia  lumbaris,  or  cruralis. 
corda   spinalis;    medulla   dorsalis;    m.  *  Conus  medullaris  ;  c.  terminalis  me- 
spinae ;  caudex  dorsalis  ;  funiculus  spi-       dullae  spinalis. 

nalis  ;  cerebrum  longum,  or  oblongum ;  5  Fissura   longitudinalis   anterior,    or 

nucha ;   myelus  ;   myelon ;   notomyelus ;  mediana. 

rhacites  ;  rhachetrum ;  processus  rachi-  6  Commissura  anterior. 

dianus;  funis  argenteus;  sacra  fistula;  7  Fissura  longitudinalis  posterior;  sul- 

vertebral  marrow.  cus  longitudinalis  medianus ;  fis.  long. 

2  Intumescentia  cervicalis.  post,  superior  et  inferior. 


534 


1HE   NERVOUS   SYSTEM. 


From  each  side  of  the  cord,  the  spinal  nerves  originate  by  a  series  of 

anterior  and  posterior  roots,  the 
attachments  of  which  give  rise  to 
slight  furrows  named  the  anterior 
and  posterior  lateral  fissures,1  Of 
these  the  posterior  is  the  more  evi- 
dent from  the  gray  substance  of  the 
interior  of  the  cord  extending  to 
its  bottom,  so  as  to  isolate  the 
white  substance  of  the  posterior 
part  of  the  cord  from  the  antero- 
lateral  part. 

The  fissures  of  the  spinal  cord 
have  led  to  its  division  into  col- 
umns. The  portions  included  be- 
tween the  anterior  median  fissure 
and  the  antero-lateral  fissures  con- 
stitute the  anterior  columns;2 
those  at  the  sides  between  the  lat- 
eral fissures  or  the  roots  of  the 
spinal  nerves  are  the  lateral  columns  ;3  and  those  between  the  posterior 
median  and  postero-lateral  fissures  are  the  posterior  columns.4  In  con- 
sequence of  the  feebly-marked  character  of  the  antero-lateral  fissures, 
the  anterior  and  lateral  portions  of  the  cord  are  usually  referred  to  under 
the  name  of  the  antero-lateral  columns. 

At  the  upper  part  of  the  cord,  a  pair  of  narrow,  white  tracts  are  ob- 
served separated  by  the  posterior  median  fissure.  These  are  named  the 
posterior  median  columns,5  and  are  continuous  with  the  posterior  pyra- 
mids of  the  medulla  oblongata. 

In  a  transverse  section  of  the  spinal  cord,  the  gray  substance  is  noticed 
to  be  arranged  in  the  form  of  two  irregular  crescentoid  bars,  situated 
one  on  each  side,  with  their  convexities  conjoined  by  a  transverse  bar. 
The  extremities  of  the  crescentoid  bars  are  called  horns,6  and  the  inter- 
vening transverse  bar  is  the  posterior  or  gray  commissure.7 

The  anterior  horns8  are  short,  broad,  and  obtuse,  and  are  inclosed 


SEGMENT  OF  THE  SPINAL  CORD.  1,  anterior  median 
fissure;  2,  posterior  median  fissure;  3,  postero- 
lateral  fissure ;  4,  antero-lateral  fissure ;  5,  anterior 
column ;  6,  lateral  column ;  7,  posterior  column ; 
8,  anterior  commissure ;  9,  anterior  horns  of  the 
gray  substance :  10,  posterior  horns;  11,  gray  com- 
missure ;  12,  anterior  root  of  a  spinal  nerve  spring- 
ing by  a  number  of  filaments  from  the  antero- 
lateral  fissure;  13,  posterior  root  from  postero- 
lateral  fissure ;  14,  ganglion  on  the  posterior  root ; 
15,  spinal  nerve  formed  by  the  union  of  the  two 
roots. 


1  Fissura  lateralis  anterior  et  poste- 
rior. 

2  Funiculi  anteriora. 

3  Funiculi  lateralia. 

4  Funiculi  posteriora. 

5  Fasciculi  graciles. 

6  Cornua ;  crura. 


7  Commissura    cinerea.       Its    central 
portion  is  the  nucleus  cinereus;  centrum 
cinereum;  commissura  gelatinosa ;  sub- 
stantia   grisea   centralis ;    gray    central 
nucleus ;    gelatinous  central  cord  of  the 
gray  commissure. 

8  Cornua  anteriora. 


THE   NERVOUS   SYSTEM.  585 

within  the  autero-lateral  columns  of  the  cord.  The  posterior  horns1  are 
longer  and  narrower,  and  are  capped  at  the  extremity  by  a  more  trans- 
lucent portion  of  the  gray  substance,  called  the  gelatinoid  substance.2 
They  separate  the  antero-lateral  from  the  posterior  columns,  and  reach 
the  bottom  of  the  postero-lateral  fissures. 

Toward  the  lower  extremity  of  the  spinal  cord,  the  crescentoid  appear- 
ance of  the  lateral  bars  of  gray  substance  becomes  indistinct,  and  the 
relative  quantity  of  the  white  substance  is  diminished. 

MEMBRANES  OF  THE  BRAIN  AND  SPINAL  CORD. 
THE  PIA  MATER. 

The  Pia  mater3  is  a  delicate  fibro-vascular  membrane  closely  investing 
the  brain  and  spinal  cord,  contributing'  to  sustain  their  structure,  and 
serving  as  a  point  of  departure  and  termination  to  their  numerous  capil- 
lary blood-vessels. 

PIA    MATER   OP   THE   BRAIN. 

The  branches  of  the  internal  carotid  and  vertebral  arteries  destined  to 
supply  the  brain  with  blood,  by  frequent  anastomosis  form  upon  its  sur- 
face an  intricate  net-work.  This  vascular  net,  in  conjunction  with 
numerous  veins,  and  strengthened  with  delicate,  interlacing  bundles  of 
fibrous  tissue,  constitutes  the  pia  mater  of  the  brain.  Processes  of  the 
membrane  extend  into  all  the  fissures  of  the  brain,  and  its  vessels  supply 
and  return  the  blood  of  the  capillaries  of  the  latter.  When  the  pia 
mater  is  detached,  the  torn  capillaries  from  the  brain  give  its  inner  sur- 
face a  flocculent  appearance. 

A  process  of  the  pia  mater,  named  the  interposed  velum,4  dips  from 
between  the  cerebrum  and  cerebellum,  beneath  the  posterior  border  of 
the  corpus  callosum,  and  above  the  quadrigeminal  body,  into  the  third 
ventricle.  The  velum  extends  along  the  under  surface  of  the  fornix,  and 
has  the  same  form.  In  the  median  line  it  incloses  the  two  ventricular 
veins,  which  lie  parallel  to  each  other,  and  end  in  a  short  trunk5  which 
opens  into  the  straight  sinus  of  the  dura  mater. 

On  each  side  the  velum  projects  beyond  the  lateral  borders  of  the  for- 

1  Cornua  posteriora.  inner  lamina  of  the  meninges ;   tunica 

2  Substantia  cinerea  gelatinosa.  cerebri  et  medullas  spinalis  propria. 

3  Pia  meninx;  mollis,  or  tenuis  mater;  4  Velum  interpositum,  triangulare,  or 
tunica,  or  meninx  interior,  vasculosa,  or  choroides  ;    tela  choroidea ;  t.   c.   supe- 
choroides;  membrana  vasculosa  cerebri;  rior;    plexus   choroideus  medius;   rete 
m.   cerebri   tenuis,  mollis,  or  propria;  mirabile;  r.  choroideum. 

5  Vena  Galeni. 


536  THE   NERVOUS   SYSTEM. 

nix,  and  forms  the  choroid  plexuses  of  the  lateral  ventricles.1  These 
plexuses  are  two  remarkable  vascular  appendages,  which  resemble  in  ap- 
pearance pieces  of  knotted  red  worsted  cord.  They  extend  from  the 
foramen  beneath  the  anterior  crura  of  the  fornix,  along  the  floor  of  the 
lateral  ventricles  at  the  side  of  the  latter,  and  descend  to  the  bottom  of 
the  middle  horns  of  the  ventricles.  Narrow  at  their  commencement, 
they  increase  in  bulk  until  they  reach  the  middle  horns  of  the  lateral 
ventricles,  and  then  decrease  to  their  termination.  In  structure  the  cho- 
roid plexuses  consist  of  portions  of  the  interposed  velum,  furnished  with 
many  villous  processes,  and  containing  tortuous  blood-vessels.  The 
villous  processes,  in  an  advanced  period  of  life,  are  frequently  found 
more  or  less  dilated  into  spherical  bodies,  from  the  size  of  a  pin-head  to 
that  of  a  pea,  and  have  been  mistaken  for  hydatid  parasites. 

On  the  under  surface  of  the  interposed  velum  are  situated  the  choroid 
plexuses  of  the  third  ventricle.2  These  are  two  narrow,  vascular  ap- 
pendages, extending  from  those  of  the  lateral  ventricles  backward  along 
the  course  of  the  ventricular  veins. 

The  choroid  plexuses  of  the  fourth  ventricle3  extend  from  the  pneu- 
mogastric  lobule  of  the  cerebellum,  join  each  other  across  the  vermiform 
process,  and  are  prolonged  a  short  distance  along  the  sides  of  the  latter. 

Connected  with  the  pia  mater  at  the  borders  of  the  great  longitudinal 
fissure,  there  is  found  a  variable  number  of  coarse,  rounded  granules, 
called  Pacchio'nian  bodies.4  These  are  usually  collected  in  groups,  and 
frequently  protrude  through  openings  of  the  dura  mater  into  the  longi- 
tudinal sinus.  The  openings  just  indicated  appear  to  result  from  pres- 
sure of  the  Pacchionian  bodies,  and  absorption  of  the  contiguous  osse- 
ous wall  of  the  cranium  is  also  occasionally  produced  by  them.  They 
were  formerly  supposed  to  be  glandular  in  character,  but  as  they  do  not 
exist  at  birth,  they  are  perhaps  to  be  viewed  as  a  pathological  produc- 
tion, notwithstanding  their  frequency. 

PIA    MATER   OF   THE    SPINAL    CORD. 

The  pia  mater  of  the  spinal  cord  has  fewer  vessels  and  more 
fibrous  tissue  entering  into  its  composition  than  that  of  the  brain, 
and  therefore  appears  denser,  stronger,  and  less  vascular.  Thin  pro- 
cesses of  the  membrane  dip  into  the  anterior  and  posterior  median 

1  Plexus  choroideus,  or  choroides ;  p.  3  Plexus  choroideus  ventriculi  quarti. 
c.  lateralis  dexter  et  sinister:  p.  choroi-  *Glandula3  Pacchionii;  glands  of  Pac- 
forines  ;    p.  reticularis ;    p.   reteformes ;  chioni ;  glandulae  durse  matris ;  g.  durae 
p.  glandulares ;    vermes   cerebri ;    retia  meningis ;     tubercula    parva ;    corpora 
mirabilia.  glandiformia ;  cerebral  granulations. 

2  Plexus  choroideus  ventriculi  tertii. 


THE  NERVOUS   SYSTEM.  537 

fissures.  In  front  it  exhibits  a  longitudinal  fibrous  band,1  and  on  each 
side,  between  the  roots  of  the  spinal  nerves,  it  forms  the  denticulate  liga- 
ment.2 This  is  a  projecting  fibrous  band  deeply  toothed  in  a  saw-like 
manner  at  its  outer  part,  the  points  of  the  dentations  being  attached  to 
the  dura  mater  in  the  intervals  of  the  spinal  nerves. 

From  the  lower  end  of  the  spinal  cord  the  pia  mater  is  continued,  as 
a  partially  hollow,  thread-like  prolongation,3  to  the  termination  of  the 
vertebral  canal,  where  it  is  attached  to  the  dura  mater.  The  hollow  of 
the  prolongation  is  apparently  occupied  by  a  continuation  of  the  gray 
substance  of  the  spinal  cord. 

THE  EPENDYMA. 

The  Epen'dyma4  is  the  delicate,  transparent,  serous  membrane,  lining 
the  ventricles  of  the  brain  and  the  central  canal  of  the  spinal  cord  of 
the  embryo.  At  birth  its  epithelium  consists  of  ciliated  cells,  but  at  a 
later  period  the  cilia  are  obliterated. 

THE  DURA  MATER. 

The  Dura  mater,5  the  exterior  investment  of  the  brain  and  spinal 
cord,  is  a  dense,  strong,  inextensible  bluish-white  membrane,  composed 
of  an  intertexture  of  bundles  of  fibrous  tissue. 

DURA    MATER  OF   THE   BRAIN.6 

This  consists  of  two  intimately  adherent  layers,  of  which  the  outer 
corresponds  with  the  periosteum  in  other  parts  of  the  skeleton,  while  the 
inner  alone  corresponds  with  the  spinal  dura  mater.  The  adhesion  of 
the  dura  mater  to  the  inner  surface  of  the  cranium  depends  on  the  many 
minute  blood-vessels  and  fibrous  processes  passing  between  the  two. 
The  connection  is  closest  along  the  sutures,  and  at  the  borders  of  the 
foramina,  and  is  especially  well  marked  at  the  base  of  the  cranium. 

The  inner  layer  of  the  dura  mater  has  a  smooth  internal  surface  closely 
invested  by  the  arachnoid  membrane.  Between  the  cerebrum  and  cere- 
bellum and  their  hemispheres  it  sends  strong  partitions  which  contribute 
to  sustain  the  mass  of  the  brain. 

1  Linea  splendens  Halleri.  5  Dura  meninx;  meninx  exterior;  m. 

2  Ligaraentum  denticulatum ;  1.  serra-  sclera  ;    m.    dennatodes  ;    m.   pacheia ; 
turn ;  1.  dentatum  ;  membrana  dentata.  crassa  meninx ;  cuticularis  membrana ; 

3  Fibrum  terminale;  nervus  impar.  membrana  externa;  m.  dura;  m.  fibrosa. 

4  Endyma,  or  indumentum  ventriculo-  6  Dura   mater   cerebri ;    d.   m.   sensu 
rum.  strictiori ;  d.  membi'ana  cerebrum  am- 

biens. 


538  THE   NERVOUS   SYSTEM. 

The  Cer'ebral  falx,1  one  of  the  partitions  just  indicated,  occupies  the 
great  longitudinal  fissure,  and  separates  the  hemispheres  of  the  cere- 
brum. Commencing  at  the  ethmoidal  crest,  to  which  it  tightly  adheres, 
it  extends  along  the  course  of  the  superior  longitudinal  sinus,  gradually 
increasing  in  breadth  until  it  joins  the  tentoriurn.  It  is  thus  shaped 
like  a  sickle,  from  whence  its  name  is  derived. 

The  Cerebel'lar  falx2  is  a  thick  fold  of  the  dura  mater  occupying  the 
valley,  and  separating  the  hemispheres  of  the  cerebellum.  It  extends 
from  the  tentorium  downward  to  the"  occipital  foramen. 

The  Tento'rium3  is  a  broad  partition  of  the  dura  mater  separating  the 
cerebrum  from  the  cerebellum.  It  is  continuous  along  its  median  line 
with  the  cerebral  falx,  from  which  it  inclines  on  each  side  downward, 
outward,  and  backward.  It  is  attached  along  the  horizontal  limbs  of 
the  occipital  cross,  and  the  superior  border  of  the  petrous  portion  of 
the  temporal  bones,  extending  to  the  posterior  clinoid  processes.  Its 
inner  border  includes  a  large  oval  space4  through  which  the  cerebral 
crura  diverge  from  the  pons  to  the  hemispheres  of  the  cerebrum. 

Through  separation  of  the  layers  of  the  dura  mater  in  certain  po- 
sitions, channels  are  formed  named  the  sinuses  of  the  dura  mater. 
These  perform  the  office  of  veins,  and  are  lined  with  a  continuation  of 
the  ordinary  epithelium  of  blood-vessels.  In  them  terminate  the  veins 
of  the  pia  mater,  which  return  the  blood  from  the  capillary  vessels  of 
the  brain. 

The  superior  longitudinal,  straight,  and  lateral  sinuses  are  three  sided, 
from  their  occupying  the  angular  intervals  along  the  lines  of  departure 
of  the  cerebral  falx  and  tentorium.  The  remaining  sinuses,  smaller  than 
those  just  mentioned,  are  generally  cylindroid,  and  occupy  the  base  of 
the  cranial  cavity.  A  description  of  the  course  of  the  sinuses  of  the 
dura  mater  is  given  in  the  account  of  the  venous  system,  page  409. 

The  meningeal  arteries  of  the  dura  mater,  which  give  rise  to  the  ar- 
borescent channels  on  the  interior  surface  of  the  cranium,  not  only  sup- 
ply the  membrane,  but  are  also  destined  to  supply  the  bones  of  the 
latter. 


1  Falx  cerebri,  major,  or  magna;  pro-  3  T.  cerebelli;  t.  cerebello   super  ex- 
cessus  falciformis   cerebri ;   septum,   or  tensum ;    tentaculum  cerebelli ;   septum 
mediastinum  cerebri;    vertical  superior  encephali;   diaphragma  cerebri;    inter- 
longitudinal  process.  septa  horizontalia  Pacchioni ;  processus 

2  Falx  cerebelli ;  f.  minor ;  processus  transversus  ;    lateral   processes  ;    trans- 
falciformis  cerebelli ;  septum  cerebelli ;  verse  septum. 

s.  parvum  occipitale ;  median  septum  of  4  Incisura  tentorii. 
the  cerebellum. 


THE   NERVOUS   SYSTEM.  539 

In  the  passage  of  vessels  and  nerves  through  foramina  at  the  base  of 
the  cranium,  the  dura  mater  becomes  continuous  with  their  fibrous 
sheaths. 

DURA    MATER   OP   THE    SPINAL   CORD.1 

This  corresponds  alone  with  the  internal  layer  of  the  dura  mater  of 
the  brain,  with  which  it  is  continuous  through  the  occipital  foramen. 
Firmly  attached  to  the  border  of  the  latter,  the  spinal  dura  mater  ex- 
tends to  the  end  of  the  vertebral  canal,  and  forms  a  loose  sheath  for  the 
spinal  cord  and  its  nerves.  It  is  unattached  to  the  periosteum  of  the 
vertebral  canal,  except  at  the  occipital  foramen,  the  interval  of  the  two 
membranous  layers  being  occupied  by  the  intra-spinal  plexus  of  veins, 
together  with  some  loose  areolar  and  adipose  tissue. 

Opposite  the  intervertebral  foramina  the  dura  mater  is  pierced  sepa- 
rately by  the  roots  of  the  spinal  nerves,  but  prolongations  of  the  mem- 
brane extend  as  sheaths  of  the  latter  and  become  firmly  attached  to  the 
periosteum  bordering  the  intervertebral  foramina. 

THE  ARACHNOID  MEMBRANE. 

The  Arach/noid  membrane2  is  a  delicate,  transparent,  and  colorless, 
serous  tunic,  intervening  between  the  pia  mater  and  the  dura  mater.  Its 
reflected  portion  adheres  closely  to  the  internal  surface  of  the  latter 
membrane  ;  while  its  investing  portion  is  connected  with  the  pia  mater 
without  dipping  into  any  of  the  fissures  or  depressions  of  the  brain  and 
spinal  cord,  except  those  which  receive  the  cerebral  falx,  the  cerebellar 
falx,  and  the  tentorium. 

The  arachnoid  membrane  is  especially  remarkable  among  serous  mem- 
branes from  its  loose  attachment  to  the  structure  beneath.  Being  con- 
nected with  the  pia  mater  by  scattered  bands  of  fibrous  tissue  and 
blood-vessels,  an  interval  is  left  between  the  two  membranes,  called  the 
subarach'noid  space.  This  varies  in  extent  in  different  positions,  but 
is  most  capacious  along  the  middle  part  of  the  base  of  the  brain,  at  the 
bottom  of  the  superior  longitudinal  fissure,  and  on  the  spinal  cord. 

A  serous  fluid,  the  cer'ebro-spinal  liquid,  amounting  to  several 
ounces,  occupies  both  the  cavity  of  the  arachnoid  membrane  and  the 
subarachnoid  space. 

The  bottom  of  the  fourth  ventricle  is  closed  by  the  arachnoid  mem- 
brane, but  the  cavity  of  the  former  communicates  with  the  subarachnoid 
space. 

1  Dura  mater  spinalis ;  pars  spinalis  durae  matris. 

2  Membrana,  or  tunica  arachnoidea;  m.  media;  t,  mucosa;  t.  serosa;  t.  aranea ; 
t.  crystallina  ;  meninx  media ;  m.  serosa ;  meningion. 


540  THE   NERVOUS   SYSTEM. 

The  roots  of  the  cerebro-spinal  nerves  are  loosely  invested  with  tubu- 
lar sheaths  of  the  arachnoid  membrane,  extending  from  the  pia  mater  to 
their  exit  through  the  dura  mater. 

THE  NERVES  OF  THE  BRAIN,  OR  THE  CEREBRAL  NERVES. 

The  Nerves  of  the  Brain,  usually  called  the  Cerebral  nerves,1  consist 
of  twelve  pairs,2  and  are  either  named  numerically  from  before  backward, 
or  from  their  function,  destination,  or  other  special  character. 

THE  OLFACTORY,  OR  FIRST  PAIR  OF  NERVES. 

The  Olfactory  nerves3  are  situated  beneath  the  anterior  cerebral 
lobes,  and  appear  rather  as  appendages  of  the  brain  than  as  true  nerves. 
They  are  small  in  comparison  with  those  of  most  lower  mammals,  in 
accordance  with  the  less  acute  sense  of  smell  in  man.  They  occupy  a 
groove  a  short  distance  from  the  longitudinal  fissure,  and  rest  in  the 
ethmoidal  gutters. 

Each  nerve  is  a  club-shaped  body,  with  a  three-sided  handle  or  ped- 
icle, and  an  oval  head  or  bulb, 

The  pedicle  of  the  olfactory  nerve  is  composed  of  white  substance  or 
nerve  fibres  below,  and  of  gray  substance  above.  The  nerve  fibres  orig- 
inate by  a  pair  of  roots4  converging  from  the  sides  of  the  anterior  per- 
forated space  at  the  inner  part  of  the  Sylvian  fissure  ;  the  gray  substance 
communicates  by  a  single  root5  with  the  space  just  mentioned. 

The  bulb6  forms  the  free  extremity  of  the  olfactory  nerve  anteriorly. 
It  is  oval,  soft,  and  composed  of  gray  substance.  From  it  emanate 
many  branches,7  which  descend  through  the  foramina  of  the  cribriform 
plate  of  the  ethmoid  bone  to  be  distributed  to  the  mucous  membrane  of 
the  upper  part  of  the  nose. 

1  Cranial,  or  encephalic  nerves.  lie  nerves ;  nerves  of  smelling,  or  olfac- 

2  Nine  pairs  of  Willis.  tion. 

3  Nervi  olfactorii ;  n.  odoratorii ;  pro-  *  Radix   externa,  or  longa,  and  radix 
cessus   mammillares ;    p.  m.  cerebri   ad  interna,  or  brevis. 

nares  ;  p.  papillares  ;    carunculge   mam-  5  Radix  media,  grisea,  or  superior, 

millares ;  ethmoidal  nerves  ;  par  primum  G  Bulbus  olfactorius  ;  b.  cinereus  ;  ol- 

nervorum  cerebri ;  first  pair  of  encepha-      factory  tubercle  or  lobe. 

7  Nervi  olfactorii;  rami  bulbi. 


THE   NERVOUS   SYSTEM. 


541 


THE  OPTIC,  OR  SECOND  PAIR  OF  NEEYES. 

The  Optic  nerves,1  among  the  largest  of  those  of  the  brain,  originate 
each  in  a  white  band,  named  the  optic  tract.2  This  starts  from  the 
quadrigerninal  and  geniculate  bodies,  winds  around  the  outer  side  of  the 
crus  of  the  cerebrum,  and  converges  to  join  that  of  the  opposite  side  in 
front  of  the  base  of  the  infundibulum.  The  conjunction  of  the  tracts 
forms  the  optic  commissnre,3  from  which  the  optic  nerves  diverge  to 
pass  through  the  optic  foramina  into  the  orbits.  The  optic  tracts  and 
commissure  throughout  their  course  intimately  adhere  to  the  contiguous 
structures  of  the  brain,  from  which  they  receive  additional  nerve  fibres. 

In  the  optic  commissure  some  of  the  nerve  fibres  cross  from  one  side 
to  the  other,  or  decussate ;  another  set  proceed  directly  from  the  optic 
tracts  to  the  corresponding  nerves ;  a  third  series,  in  the  form  of  loops, 
appear  to  associate  the  tracts  together ;  and  a  fourth  series,  in  the  same 
manner,  conjoin  the  two  nerves  independently  of  the  tracts. 

The  optic  nerves  are  those  of  vision,  and  terminate  in  the  retina  of 
the  eyeball. 

THE  OCULO-MOTOR,  OR  THIRD  PAIR  OF  NERYES. 

The   Oc'ulo-motor  nerves4  ap-  FIG.  332. 

pear  at  the  surface  of  the  brain, 
springing  from  the  inner  side  of  the 
cerebral  crura,  just  in  advance  of 
the  pons.  Their  nerve  fibres  are 

OCULO-MOTOR  AND  ABDUCENT  NERVE,  the  upper 
part  of  the  right  orbit  removed.  1,  oculo-motor 
nerve ;  2,  3,  branch  to  the  superior  straight  and 
oblique  muscles  ;  4,  5,  branches  to  the  internal  and 
inferior  straight  muscles;  6,  branch  to  the  inferior 
oblique  muscle ;  7,  branch  from  the  latter  to  the 
ophthalmic  ganglion ;  8,  abducent  nerve  to  the  ex- 
ternal straight  muscle ;  9,  communicating  filaments 
between  the  abducent  nerve  and  the  carotid  plexus 
of  the  sympathetic.  To  their  outer  side  is  the  tri- 
facial  nerve.  10,  ciliary  nerves  perforating  the 
sclerotic  coat  of  the  eyeball,  and  passing  forward 
between  it  and  the  choroid  to  the  ciliary  muscle 
and  iris. 

traceable  to  the  gray  substance  in  the  interior  of  the  crura  of  the  cer- 
ebrum and  the  pons. 


1  Nervi  optici ;  n.  visorii ;  par  secun- 
dum,    opticum,    or    visorium ;     ocular 
nerves  ;  nerves  of  sight  or  vision. 

2  Tractus  opticus. 

3  Chiasma,   or  commissura  nervorum 
opticorum. 


4  Nervi  oculo-motores;  n.  motores  ocu- 
lorum ;  n.  oculares  communes ;  n.  oph- 
thalmic! externi ;  common  oculo-muscu- 
lar  nerves ;  par  tertium. 


542  THE   NERVOUS   SYSTEM. 

Passing  obliquely  forward  and  outward,  the  oculo-motor  nerve  pierces 
the  dura  mater  in  front  of  the  posterior  clinoid  process,  and,  after  travers- 
ing the  outer  wall  of  the  cavernous  sinus,  it  divides  into  two  branches, 
which  enter  the  orbit  through  the  sphenoidal  foramen. 

Of  the  two  branches,  the  upper  and  smaller  is  distributed  to  the  pal- 
pebral  elevator  and  superior  straight  muscles ;  while  the  lower  one  sup- 
plies the  internal  and  inferior  straight  and  the  inferior  oblique  muscles, 
and  is  connected  by  a  short  branch1  with  the  ophthalmic  ganglion. 

The  name  of  the  oculo-motor  nerve  indicates  its  function. 

THE  PATHETIC,  OR  FOURTH  PAIR  OF  NERVES. 

The  Pathetic  nerves,2  the  smallest  of  those  connected  with  the 
brain,  start  from  the  upper  part  of  the  "  valve  of  the  brain,"  immediately 
behind  the  quadrigeminal  body.  Their  fibres  are  traceable  to  the  gray 
substance  of  the  pons  and  the  floor  of  the  fourth  ventricle. 

Each  pathetic  nerve  appears  like  a  white  thread  winding  around  the 
outer  side  of  the  crus  of  the  cerebrum.  Piercing  the  dura  mater  just 
behind  the  oculo-motor  nerve,  it  accompanies  this  through  the  outer 
wall  of  the  cavernous  sinus  and  the  sphenoidal  foramen  into  the  orbit." 
It  is  motor  in  its  function,  and  is  distributed  to  the  superior  oblique 
muscle  of  the  eye. 

THE  TRIFACIAL,  OR  FIFTH  PAIR  OF  NERVES. 

The  Trifa'cial  nerves3  are  the  largest  of  those  derived  from  the 
brain.  They  arise  by  two  roots  of  unequal  size,  which  emerge  from  the 
side  of  the  pons  at  its  fore  part  inferiorly. 

The  large  root4  of  the  trifacial  nerve,  sensory  in  its  function,  consists 
of  numerous  bundles  of  nerve  fibres,  which  may  be  traced  through  the 
pons  into  the  restiform  body  and  the  gray  substance  of  the  floor  of  the 
fourth  ventricle.  The  small  root,5  motor  in  its  function,  though  trace- 
able through  the  pons  to  the  medulla  oblongata,  has  not  had  its  origin 
satisfactorily  determined. 

The  two  roots  of  the  trifacial  nerve,  the  smaller  concealed  behind  the 
large  one,  pass  through  an  oval  aperture  of  the  dura  mater,  near  the 

1  Radix  brevis  ganglii  ciliaris ;  short  par  trigeminum  ;  par  trium  funiculorum. 
root  of  the  ophthalmic  ganglion.  Sing. :  n.  divisus ;  n.  trimellus  ;  n.  mix- 

2  Nervi  pathetici;    n.  trochleares ;   n.  tus  ;    n.  quintus  ;   n.  sympatheticus  me- 
oculo-musculares   superior,   minimi,    or  dius  ;  n.  anonymus ;  n.  innominatus. 
interni;  par  quartum.  4  Radix  major,  posterior,  inferior,  or 

3  N.  trifaciales ;  n.  trigemini ;  trigem-  longior. 

inal  nerves ;  n.  gustatorii ;  par  quintum ;  6  Radix  minor,  anterior,  or  superior. 


THE   NERVOUS   SYSTEM. 


543 


apex  of  the  petrous  portion  of  the  temporal  bone.  The  large  root 
terminates  in  the  semilunar  ganglion,  which  rests  in  a  slight  depression 
in  front  of  the  apex  of  the  petrous  portion  of  the  temporal  bone  ;  while 
the  small  root  passes  beneath  the  ganglion,  and  simply  lies  in  contact 
with.it. 

The-  semilunar  ganglion1  of  the  trifacial  nerve  is  a  large  crescentic 
body,  with  its  concavity  upward,  and  receiving  the  diverging  fibres  of  the 
large  root  of  the  nerve.  From  its  convexity  emanate  the  ophthalmic 
and  superior  maxillary  nerves,  and  a  third  branch,  which  joins  the 
small  root  of  the  trifacial  to  form  the  inferior  maxillary  nerve. 

THE   OPHTHALMIC   NERVE.2 


FIG.  333. 


This  is  the  first  division  of  the  trifacial  nerve,  and  the  smallest  branch 
from  the  semilunar  gan- 
glion. After  traversing 
the  outer  wall  of  the 
cavernous  sinus,  it  di- 
vides into  three  branches, 
which  pass  through  the 
sphenoidal  foramen  into 
the  orbit. 

TRIFACIAL  NERVE,  the  upper  part 
of  the  orbit  and  temporal  fossa  re- 
moved. 1.  semihinar  ganglion;  2, 
ophthalmic  nerve;  3,  lachrymal 
nerve;  4,  frontal  nerve;  5,  6,  its  two 
principal  branches;  7,  a  branch 
passing  from  the  orbit  above  the 
pulley  of  the  superior  oblique  mus- 
cle ;  8,  nasal  nerve ;  9,  its  exter- 
nal nasal  branch ;  10,  course  of  the 
internal  nasal  nerve  from  the  orbit 
into  the  cranium,  and  nose;  11, 
12,  13,  temporal  branches  of  the 
inferior  maxillary  nerve;  14,  com- 
mencement of  the  auriculo-tempo- 
ral  nerve;  15,  greater  petrosal . 
nerve;  I,  olfactory  nerve;  II,  optic 
nerves;  III,  oculo-motor  nerve;  IV, 
pathetic  nerve  to  the  superior  ob- 
lique muscle  of  the  eye;  V,  trifacial 

nerve;  its  small  root  visible  beneath  the  cut  end  of  the  large  root,  which  forms  the  semilunar  ganglion 
dividing  into  the  ophthalmic,  superior  and  inferior  maxillary  nerves;  VI,  abducent  nerve;  VII,  facial, 
included  inagroove  of  the  auditory  nerve,  VIII,  both  entering  the  auditory  meatus;  IX,  glosso-pharyngeal, 
X,  pneumogastric,  and  XI,  accessory  nerves  emerging  at  the  jugular  foramen;  XII,  hypoglossal  nerve. 

1  G.  semilunare;  g.  Gasseri;  Gasserian  ganglion;  ganglion  of  Gasser;  intumes- 
centia,  or  moles  gangliformis;  i.  semilunaris;  taenia  nervosa   Halleri;  ganglion  of 
the  fifth  nerve. 

2  Nervus  ophthalmicus  ;  n.  orbito-frontalis. 


544  THE  NERVOUS   SYSTEM. 

The  Lach/rymal  nerve,1  one  of  the  branches  of  the  ophthalmic,  passes 
along  the  outer  part  of  the  orbit  to  be  distributed  to  the  lachrymal  gland 
and  upper  eyelid. 

The  Frontal  nerve,2  the  largest  branch  of  the  ophthalmic,  passes  along 
the  roof  of  the  orbit,  and  divides  into  two  branches,  of  which  one3 
emerges  at  the  supra-orbital  foramen,  the  other4  between  the  latter  and 
the  pulley  of  the  superior  oblique  muscle,  and  both  are  distributed  to 
the  skin  and  muscles  of  the  forehead  and  upper  eyelid. 

The  Nasal  nerve,5  the  remaining  branch  of  the  ophthalmic,  passes 
above  the  optic  nerve  and  along  the  inner  side  of  the  orbit  to  the  anterior 
ethmoidal  foramen,  where  it  divides  into  the  internal  and  external  nasal 
nerves.  In  its  course  within  the  orbit  it  is  connected  by  an  anastomotic 
filament6  with  the  ophthalmic  ganglion,  and  gives  off  two  or  three  ciliary 
nerves.7 

The  internal  nasal  nerve8  passes  through  the  anterior  ethmoidal  fora- 
men and  enters  the  cranium,  when  it  proceeds  forward  to  the  most  ante- 
rior of  the  foramina  of  the  ethmoid  bone,  and  descends  to  supply  the 
mucous  membrane  at  the  fore  part  of  the  nose. 

The  external  nasal  nerve9  passes  from  the  orbit  beneath  the  pulley  of 
the  superior  oblique  muscle,  and  is  distributed  to  the  eyelids  with  their 
muscle,  the  lachrymal  sac,  and  the  skin  of  the  nose. 

THE    OPHTHALMIC   GANGLION.10 

This  is  a  small,  reddish-gray  body,  situated  at  the  back  part  of  the 
orbit,  between  the  optic  nerve  and  the  external  straight  muscle.  It  is 
imbedded  in  areolar  and  adipose  tissue,  and  is  connected  by  branches 
with  the  nasal  nerve  of  the  ophthalmic,  the  oculo -motor  nerve,  and 
the  carotid  plexus  of  the  sympathetic.  From  its  fore  part  emanate  about 
a  dozen  cil'iary  nerves.11  These,  together  with  the  two  or  three  ciliary 
branches  from  the  nasal  nerve,  pierce  the  back  part  of  the  sclerotic  coat, 
and  advance  between  it  and  the  choroid  coat  to  be  distributed  to  the 
ciliary  muscle  and  iris. 

1  Nervus  lachrymalis.  7  Long  ciliary  nerves. 

2  N.  frontalis ;  n.  front o-palpebralis.  8  N.  nasalis  interims;  n.  ethmoidalis. 

3  N.  supra-orbitalis ;    n.  frontalis  ex-  9  N.  infra-trochlearis ;    n.  nasalis  ex- 
ternus,  or  major.  ternus. 

*  N.  supra-trochlearis ;  n.  frontalis  in-  10  Ganglion  ophthalmicum ;  g.  ciliare  ; 

ternus,  or  minor.  g.  lenticulare ;    g.  semilunare ;    g.  orbi- 

5  N.  nasalis  ;  n.  nasarius  ;  n.  naso-ci-  tale ;  ciliary  or  lenticular  ganglion, 
liaris  ;  n.  naso-ocularis.  n  Short  ciliary  nerves ;  nervi  ciliares 

6  Long  root  of  the  ophthalmic  gan-  breves, 
glion. 


THE   NERVOUS   SYSTEM. 


545 


OPHTHALMIC  GANGLION — THE  OUTER 
PART  OF  THE  RIGHT  ORBIT  REMOVED. 

I,  optic  nerve;  2,  oculo-motor  nerve; 
3,  branch  to  the  superior  straight  and 
oblique  muscles ;  4,  branch  to  the  in- 
ferior oblique   muscle;   5,  abducent 
nerve  to  the  external  straight  muscle ; 
C,  trifacinl   nerve,  its  ganglion  and 
three  principal  branches;  7,  ophthal- 
mic nerve ;  8,  nasal  nerve ;  9,  ophthal- 
mic ganglion;  10,  its  communicating 
branch  with  the  oculo-motor  nerve ; 

II,  do.  with  the  ophthalmic  nerve; 
12,  do.  with  the  carotid  plexus  of  the 
sympathetic ;   13,  the  ciliary  nerves ; 
14,  frontal  nerve. 


FIG.  334. 


THE   SUPERIOR   MAXILLARY   NERVE.1 

This  is  the  second  division  of  the  trifacial  nerve,  and  is  intermediate 
in  size  and  position  to  the  others.     Starting  from  the  middle  of  the 

FIG.  335. 


SUPERIOR  MAXILLARY  NERVE — THE  EXTERNAL  WALL  OF  THE  LEFT  ORBIT  AND  OF  THE  SUPERIOR  MAXILLARY 
BONE  REMOVED.  I,  superior  maxillary  nerve  in  its  course  through  the  infra-orbital  canal;  2,  3,  posterior 
dental  nerves;  4,  anterior  dental  nerve;  5,  anastomosis  between  the  dental  nerves;  6,  spheno-palatine 
ganglion;  the  branch  from  the  superior  maxillary  nerve  above  is  the  commencement  of  the  temporo-malar 
nerve;  7,  pterygoid  nerve  ;  8,  greater  petrosal  nerve  joining  the  facial  nerve  ;  9,  deep  petrous  nerve  join- 
ing the  carotid  plexus  of  the  sympathetic ;  10,  abducent  nerve  with  its  communicating  branches  of  the 
latter  plexus;  11,  superior  cervical  ganglion;  12,  ascending  branches  to  the  carotid  plexus;  13,  facial 
nerve;  14,  glosso-pharyngeal  nerve;  15,  the  tympanic  nerve;  16,  branch  to  the  carotid  plexus ;  17, 18, 19, 
branches  to  the  round  and  oval  windows  and  Eustachian  tube;  20,  branch  to  the  smaller  petrosal 
nerve,  21. 

semilunar  ganglion  as  a  flattened  cord,  it  assumes  a  rounded  form,  and 
passes  from  the  cavity  of  the  cranium  through  the  rotund  foramen  of 
the  sphenoid  bone.  It  then  crosses  the  upper  part  of  the  pterygo-max- 


Nervus  maxillaris  superior. 
35 


546  THE   NERVOUS   SYSTEM. 

illary  fossa,  and  enters  the  infra  orbital  canal,1  through  which  it  advances 
to  the  face.  In  its  course  it  gives  off  the  temporo-malar,  spheno-pala- 
tine,  dental,  and  infra-orbital  nerves. 

The  Temporo-ma'lar  nerve2  enters  the  orbit  through  the  spheno-max- 
illary  foramen,  and  divides  into  filaments,  which  are  transmitted  by 
foramina  of  the  malar  bone  to  the  skin  of  the  temple  and  cheek.  It 
anastomoses  with  the  lachrymal  and  facial  nerves. 

The  Sphe'no-pal'atine  nerves3  are  two  short  branches  descending  to 
join  the  spheno-palatine  ganglion. 

The  Dental  nerves4  consist  of  posterior  and  anterior  branches.  The 
posterior  dental  nerves,5  of  which  there  are  two  or  three,  descend 
behind  the  tuberosity  of  the  superior  maxillary  bone,  and  enter  small 
canals  in  the  outer  wall  of  the  maxillary  sinus  to  supply  the  back  teeth. 
One  of  the  branches  also  supplies  the  upper  gum.  The  anterior  dental 
nerve6  comes  off  from  the  superior  maxillary  within  the  infra-orbital 
canal,  and  descends  in  the  anterior  wall  of  the  maxillary  sinus  to  supply 
the  front  teeth.  The  anterior  and  posterior  dental  nerves  anastomose 
with  one  another,  and  also  give  branches  to  the  lining  membrane  of  the 
maxillary  sinus. 

The  Infra-orbital  nerves7  are  the  terminal  branches  of  the  superior 
maxillary,  emerging  at  the  infra-orbital  foramen  to  be  distributed  to  the 
lower  eyelid,  the  upper  lip,  the  side  of  the  nose,  and  the  mucous  mem- 
brane of  the  cheek. 

THE   SPHENO-PALATINE   GANGLION.8 

This  is  a  small,  triangular  body,  situated  in  the  pterygo-maxillary 
fossa,  near  the  spheno-palatine  foramen.  It  is  joined  by  the  spheno- 
palatine  branches  of  the  superior  maxillary  nerve,  and  besides  giving 
small  filaments9  to  the  upper  part  of  the  pharynx,  sends  off  the  nasal, 
palatine,  and  pterygoid  nerves. 

1  Within  which  it  is  usually  called  the          6  N.  dentalis,   or   alveolaris   superior 
infra-orbital  nerve ;  nervus  infra-orbi-      anterior. 

talis.  *  N.  infra-orbitales. 

2  N.  subcutaneus  malae  ;  n.  orbitarius.  8  G.  spheno-palatinum  ;    g.  pterygo- 
8  Nervi  spheno-palatini ;  n.  pterygo-      palatinum;  g.  Meckelii;  Meckel's  gan- 

palatini.  glion  ;  ganglion  of  Meckel ;    g.  nasale ; 

4  N.  dentales;  n.  d.  superiores;  n.  al-      g  rhinicuni ;  g.  sphenoidale. 
veolares  superiores.  9  Kami  pharyngei. 

5  N.  dentales,  or  alveolares  superiores 
posteriores. 


THE  NERVOUS   SYSTEM. 


547 


The  Nasal  nerves1  consist  of  half  a  dozen  or  more  small  branches, 
which  pass  through  the  spheno-palatine  foramen  to  supply  the  mucous 
membrane  of  the  nose,  including  its  partition,  its  outer  wall,  and  the 
ethmoidal  and  sphenoidal  sinuses.  One2  of  the  branches,  descending 
obliquely  on  the  partition,  passes  through  the  naso-palatine  canal  to  the 

roof  of  the  mouth. 

FIG.  336. 


VIEW  OF  THE  SPHENO-PALATINE  GANGLION,  THE  OUTER  WALL  OF  THE  LEFT  NASAL  CAVITY,  AND  THE  OLFACTORY; 

NERVE.  1,  olfactory  nerve ;  2,  nasal  branch  of  the  ophthalmic  nerve;  3, spheno-palatine  ganglion;  4,5, 
6,  palatine  nerves;  7,  branch  to  the  nose;  8,  nasal  nerve  to  the  outer  wall  of  the  nose;  9,  do.  to  the  inner 
•wall ;  10,  pterygoid  nerve ;  11,  facial  nerve ;  12,  deep  petrous  nerve  joining  the  carotid  plexus,  13 ;  the 
other  branch  of  the  pterygoid  is  the  larger  petrosal  nerve,  which  joins  the  facial. 

The  Pal'atine  nerves,3  of  which  there  are  usually  three,  descend 
through  the  posterior  palatine  canal  and  its  divisions  to  be  distributed 
to  the  hard  and  soft  palate,  the  palatine  arches,  the  uvula,  and  the  tonsil. 
From  the  largest  palatine  nerve,4  in  its  course  one  or  two  branches3  are 
given  off  to  the  outer  wall  of  the  nose. 

The  Pter'ygoid  nerve6  proceeds  from  the  spheno-palatine  ganglion 
backward  through  the  pterygoid  canal  of  the  sphenoid  bone,  and  divides 
into  two  branches.  One  of  these,  the  deep  petrous  nerve,7  pierces  the 
cartilage  occupying  the  lacerated  foramen,  and  joins  the  carotid  plexus 
of  the  sympathetic  nerve.  The  other  branch,  named  the  greater  petro- 


1  N.  nasales  superiores   anteriores  et 
posteriores,  et  naso-palatinus. 

2  N.  naso-palatinus  ;  n.  naso-palatinus 
Scarpae  ;  n.  septi  narium. 

3  N.  palatini ;  n.  p.  anterior  et  medius, 
posterior,  or  minus  posterior  et  mini- 
mus exterior. 


4  N.  palatinus  anterior,  or  major. 

5  N.  nasales  inferiores. 

6  N.  pterygoideus ;    n.  Vidianus ;  Vj- 
dian  nerve  ;  n.  recurrens  Vidianus. 

7  Ramus  sympatheticus ;  r.  profundus 
nervi  Vidiani. 


648  THE   NERVOUS   SYSTEM. 

sal  nerve,1  enters  the  cranial  cavity  through  the  cartilage  of  the  lacerated 
foramen,  and  passes  into  a  canal  on  the  front  of  the  petrous  portion  of 
the  temporal  bone  to  join  the  facial  nerve. 

THE   INFERIOR   MAXILLARY    NERVE.2 

This  is  formed  by  the  union  of  the  small  root  of  the  trifacial  nerve 
with  the  third  branch  of  its  semilunar  ganglion.  It  is  larger  than  the 
ophthalmic  or  superior  maxillary  nerve,  and  emerges  from  the  cavity  of 
the  cranium  through  the  oval  foramen  of  the  sphenoid  bone.  Imme- 
diately after  its  exit  it  separates  into  two  divisions,  of  which  the  smaller 
receives  nearly  all  the  fibres  of  the  small  or  motor  root  of  the  trifacial 
nerve  ;  while  theMarger  division  receives  most  of  the  fibres  emanating 
from  the  semilunar  ganglion. 

The  smaller  division  of  the  inferior  maxillary  nerve  resolves  itself 
into  a  number  of  muscular  branches,3  of  which  two4  supply  the  tem- 
poral muscle,  one5  the  masseter,  one6  the  buccinator,  and  two7  the  ptery- 
goid  muscles. 

The  larger  or  sensory  division  of  the  inferior  maxillary  nerve  is  con- 
nected on  its  inner  side  with  the  otic  ganglion,  and  divides  into  the 
auriculo-temporal,  lingual,  and  inferior  dental  nerves. 

The  Auric 'ulo-tem'poral  nerve,8  the  smallest  of  the  three  branches 
just  indicated,  is  directed  outwardly  between  the  ear  and  the  articulation 
of  the  lower  jaw,  and  ascends  to  be  distributed  to  the  skin  of  the  temple. 
In  its  course  it  gives  branches  to  the  external  ear,  the  articulation  of 
the  lower  jaw,  and  the  parotid  gland  ;  and  it  anastomoses  with  the  facial 
nerve. 

The  LinrgTial  nerve9  curves  downward  and  forward  between  the 
pterygoid  muscles  to  the  side  of  the  tongue,  along  which  it  continues  to 
the  tip,  beneath  the  sublingual  gland  and  in  contact  with  the  mucous 
membrane  of  the  mouth.  In  its  course  it  is  joined  by  the  tympanic 
branch10  of  the  facial  nerve,  and  gives  small  branches  to  the  mucous 

1  Greater  superficial  petrosal  nerve ;  5  N.  massetericus. 
nervus  petrosus  superficialis  major  ;  n.  6  N.  buccinatorius. 

superior,  or  superficialis  nervi  Vidiani.  7  N.  pterygoideus   internus  et   exter- 

2  Nervus  maxillaris  inferior ;  n.  crota-       nus. 

phitico-buccinatorius  et  maxillaris  infe-  8  N.  auriculo-temporalis  ;  n.  tempora- 

rior;  ramus  tertius  nervi  quinti;   third  lis  superficialis ;  n.  auricularis  anterior, 

branch  of  the  fifth,  or  trigeminal  nerve.  9  N.  lingualis ;  n.  gustatorius  ;  gusta- 

3  Kami  musculares.  tory  nerve. 

4  N.  temporalis  profundus  anterior  et  10  Chorda  tympani. 
posterior. 


THE  NERVOUS  SYSTEM. 


549 


membrane  of  the  mouth,  sublingual  gland,  and  the  submaxillary  gan- 
glion. Its  terminal  branches  perforate  the  muscular  structure  of  the 
tongue,  and  ascend  almost  vertically  to  end  in  the  papillae  of  taste. 


FIG.  337. 


DISTRIBUTION  OF  THE  iNrERiOR  MAXILLARY  NERVE.  1,  muscular  branch  to  the  masseter  muscle;  2,  5,  7, 
branches  to  the  temporal  muscle  ;  3,  branch  to  the  buccinator,  anastomosing  with  one  from  the  facial  at 
4;  6,  external  pterygoid  muscle;  8,  auriculo-temporal  nerve;  9,  brandies  to  the  temple;  10,  branches  to 
the  ear;  11,  its  anastomosis  with  the  facial ;  12,  lingual  nerve ;  13,  branch  to  the  mylo-hyoid  muscle  from 
the  inferior  dental  nerve,  14;  15,  branches  to  the  teeth;  16,  terminal  branches  to  the  lower  lip  and  chin. 

The  Inferior  dental  nerve,1  a  little  larger  than  the  lingual,  descends 
in  company  with  it,  but  diverges  to  enter  the  dental  canal  of  the  inferior 
maxillary  bone.  In  its  course  through  the  canal  it  supplies  the  lower 
teeth  ;  and  it  finally  emerges  at  the  mental  foramen  to  be  distributed  to 
the  lower  lip  and  chin.  Before  entering  the  dental  canal  it  gives  a 
branch2  to  the  muscles  and  skin  of  the  floor  of  the  mouth. 


1  N.  dentalis  inferior;  n.  maxillaris  inferior;  n.  mandibularis. 

2  Ramus  mylo-hyoideus. 


550  THE   NERVOUS   SYSTEM 


THE   OTIC   GANGLION. 


This  is  a  small,  flattened,  oval  body,  situated  on  the  inner  side  of  the 
sensory  division  of  the  inferior  maxillary  nerve,  with  which  it  is  con- 
nected by  several  short  filaments.  Behind  it  is  the  great  meningeal 
artery,  and  it  is  connected  by  a  filament  with  the  sympathetic  plexus  fol- 
lowing this  vessel.  It  gives  branches  to  the  tympanic  tensor  and  cir- 
cumflex palatine  muscles,  and  an  anastomotic  filament  to  the  auriculo- 
temporal  nerve.  From  it  emanates  the  small  petro'sal  nerve,2  which 
enters  the  cranium  through  a  fine  canal  in  the  spinous  process  of  the 
sphenoid  bone,  and  then  traverses  a  canal  in  the  front  of  the  petrous 
portion  of  the  temporal  bone,  to  join  the  facial  nerve  and  the  tympanic 
branch  of  the  glosso-pharyngeal  nerve. 

THE    SUBMAXILLARY   GANGLION.3 

This  is  a  minute  body  situated  on  the  trunk  of  the  lingual  nerve,  just 
above  the  submaxillary  gland.  It  is  connected  by  filaments  with  the 
lingual  nerve,  which  are  partly  traceable  to  the  tympanic  branch  of  the 
facial.  It  is  also  connected  with  the  sympathetic  plexus  of  the  facial 
artery,  and  sends  all  its  branches  to  the  submaxillary  gland. 

THE  ABDUCENT,  OR  SIXTH  PAIR  OF  NERVES. 

The  Abdu/cent  nerves4  appear  at  the  surface  of  the  brain,  between 
the  summits  of  the  pyramidal  bodies  of  the  medulla  oblongata  and  the 
pons.  Their  fibres,  forming  a  large  and  small  bundle,  for  the  most  part 
originate  from  the  pyramidal  bodies,  a  few  being  derived  from  the  pons. 

The  abducent  nerve  appears  as  a  white  thread,  but  is  larger  than  the 
pathetic  nerve.  It  proceeds  forward,  traverses  the  cavernous  sinus,  from 
the  cavity  of  which  it  is  separated  by  the  lining  membrane,  and  passes 
through  the  sphenoidal  foramen  into  the  orbit.  In  the  cavernous  sinus 
it  lies  at  the  outer  side  of  the  internal  carotid  artery,  and  is  connected 
with  its  sympathetic  plexus  by  a  pair  of  filaments.  In  the  orbit  it 
passes  between  the  two  heads  of  the  external  straight  muscle,  to  which 
it  is  distributed. 

1  Ganglion  oticum ;  g.  auriculare ;  g.       nus   Meckelii ;    plexus   gangliosus  sub- 
Arnoldi;  ganglion   of   Arnold;  otogan-       maxillaris. 

glium ;  g.  maxillo-tympanicum.  *   Nervi   abducentes.     Sing. :    nervus 

2  Small   superficial  petrosal    nerve;       abducens;  n.  oculo-muscularus  externus 
nervus  petrosus  superficialis  minor.  or  posterior;   n.  ocularis  externus;    n. 

3  G.  submaxillare ;  g.  linguale  ;  g.  mi-       motor-oculi  externus ;  n.  timidus. 


THE   NERVOUS   SYSTEM. 


551 


THE  FACIAL,  OB  SEVENTH  PAIR  OF  NERVES. 

The  Facial  nerves1  emerge  from  the  depression  immediately  back  of 
the  pons,  between  the  olivary  and  restiform  bodies.     They  have  a  large 

Fio.  338. 


THE  FACIAL  NERVE.  1,  trunk  of  the  nerve  emerging  at  the  stylo-mastoid  foramen ;  2,  its  deep  auricu- 
lar branch;  3,  anastomosis  of  the  latter  with  the  great  auricular  nerve  of  the  cervical  plexus;  4,  5,  6, 
branches  to  the  contiguous  muscles;  7,  8,  branches  of  the  facial  to  the  digastric  and  stylo-hyoid  muscles  ; 
9,  temporo-facial  division  of  the  nerve;  10,  branch  to  the  temple, anastomosing  with  the  auriculo-temporal 
nerve;  il,  temporal  branches;  12,  /ygomatic  branches;  13,  infra-orbital  branches;  14, 15,  cervico-facial 
division  of  the  facial  nerve;  14,  buccal  branches;  16,  inferior  maxillary  branches;  17,  cervical  branches ; 
18,  auriculo-temporal  nerve;  19,  20,  terminal  branches  of  the  frontal  nerve;  21,  terminal  branch  of  the 
lachrymal  nerve;  22,  external  nasal  nerve;  23,  branch  of  the  temporo-malar  nerve;  24,  terminal  branch 
of  the  internal  nasal  nerve;  25,  infra-orbital  nerves;  26,  anastomosis  between  the  buccal  branch  of  the 
inferior  maxillary  nerve  and  the  buccal  branches  of  the  facial  nerve;  27,  terminal  branches  of  the  infe- 
rior dental  nerve;  28,  great  occipital  nerve;  23,31,  branches  of  the  great  auricular  nerve;  30,  small 
occipital  nerve ;  32,  superficial  cervical  nerve,  anastomosing  with  the  facial  nerve. 


1  Nervi  faciales ;  par  septimum ;  p. 
faciale.  Sing.:  portio  dura  nervi  sep- 
timi;  n.  communicans  faciei;  n.  primus 
paris  septimi ;  n.  sympathetlcus  parvus 


or  minor ;  ramus  durior  septimse  conju- 
gationis;  respiratory  nerve  of  the  face; 
portio  dura  nerve ;  portio  dura  of  the 
seventh  pair  of  nerves. 


552  THE  NERVOUS   SYSTEM. 

root  whose  fibres  are  derived  from  the  restiform  body,  and  a  small  root 
'  from  the  floor  of  the  fourth  ventricle.  The  two  roots  together  accom- 
pany the  auditory  nerve,  lying  in  a  groove  on  its  upper  part,  and  pass 
down  the  internal  auditory  meatus.  At  the  bottom  of  this  passage  the 
facial  leaves  the  auditory  nerve  and  enters  the  Fallopian  canal,  through 
the  winding  course  of  which  it  pursues  its  way  to  the  stylo-mastoid 
foramen. 

At  the  position  in  which  the  Fallopian  canal  turns  backward,  the 
facial  nerve  presents  a  gangliform  enlargement,1  which  is  joined  by 
the  larger  petrosal  nerve,  a  branch  of  the  smaller  petrosal  nerve,  and  a 
filament  from  the  sympathetic  plexus  following  the  great  meningeal 
artery. 

In  the  descending  portion  of  the  Fallopian  canal  the  facial  nerve 
sends  a  branch  to  the  stapedius  muscle,  and  gives  off  the  tympanic 
nerve.2  This  enters  the  tympanum  through  a  foramen  near  the  pyra- 
mid, and  proceeds  forward  to  emerge  at  the  glenoid  fissure,  from  which 
it  descends  between  the  pterygoid  muscles  to  join  the  lingual  nerve.  In 
its  course  it  lies  in  contact  with  the  tympanic  membrane,  between  this 
and  the  handle  of  the  mallet,  and  is  separated  from  the  cavity  of  the 
tympanum  by  its  lining  mucous  membrane. 

Below  the  stylo-mastoid  foramen  the  facial  nerve  gives  branches  to 
the  digastric  and  stylo -hyoid  muscles,  anastomotic  filaments  to  the  auric- 
ulo-temporal  nerve,  and  sends  off  the  deep  auricular  nerve.3  This 
ascends  between  the  ear  and  the  mastoid  process,  and  is  distributed  to 
the  muscles  of  the  back  of  the  ear  and  the  occipital  region. 

From  the  stylo-mastoid  foramen  the  facial  nerve  turns  forward  through 
the  parotid  gland,  and  divides  into  numerous  diverging  branches,4  which 
anastomose  with  one  another  on  the  side  of  the  cheek,  and  are  distrib- 
uted over  the  face,  extending  from  the  temple  to  the  upper  part  of  the 
neck.  The  branches  of  distribution  form  two  groups,  named  the  tem- 
poro-facial  and  cervico-facial  divisions  of  the  nerve. 

The  Temporo-facial  division  of  the  facial  nerve  ramifies  on  the  side 
of  the  face  from  the  temple  to  the  vicinity  of  the  mouth,  forming  an 
intricate  plexus,  and  anastomosing  with  the  contiguous  terminal  branches 
of  the  trifacial  nerve.  Its  branches,  mainly  distributed  to  the  muscles 
of 'the  temple,  forehead,  eyelids,  cheek,  nose,  and  upper  lip,  are  named, 
from  their  special  position,  temporal,  zygomatic,  and  infra-orbital. 

1  Intumescentia    gangliformis;     gan-  3  Nervus  auricularis  profundus ;  pos- 
glion  geniculare.                                                 terior,  or  exterior. 

2  Chorda  tympani ;  funiculus  tympani.  4  Pes  anserinus;  plexus  parotideus. 


THE   NERVOUS   SYSTEM.  553 


The  Cervico-facial  division  of  the  facial  nerve  is  distributed  to  the 
lower  part  of  the  face  and  the  upper  part  of  the  neck.  Its  upper  or 
buccal  branches  anastomose  with  the  lower  ones  of  the  preceding 
division,  and  supply  the  muscles  of  the  cheek,  nose,  and  upper  lip.  The 
inferior  maxillary  branches  supply  the  muscles  of  the  lower  lip  and 
chin,  and  anastomose  with  the  inferior  dental  nerve.  The  cervical 
branches  anastomose  with  the  upper  cervical  nerves,  and  supply  the 
subcutaneous  cervical  muscle. 

The  facial  nerve  is  the  motor  nerve  of  the  face,  and  is  the  avenue 
through  which  its  muscles  are  acted  upon  by  the  emotions.  A  few  sen- 
sory filaments  which  it  contains  are  derived  through  anastomosis  with 
the  pneumogastric  and  trifacial  nerves. 


THE  AUDITORY,  OR  EIGHTH  PAIR  OF  NERV 


The  Auditory  nerves1  have  their  origin  in  the  transverse  white  striae 
of  the  floor  of  the  fourth  ventricle,  and  turn  forward  around  the  resti- 
form  bodies,  from  which  they  also  receive  a  few  fibres.  Each  nerve  is 
then  directed  outwardly,  in  company  with  the  facial  nerve,  and  passes 
into  the  internal  auditory  meatus,  from  whence  it  is  distributed  to  the 
labyrinth. 

The  auditory  nerve  is  the  special  one  of  hearing,  and  is  more  particu- 
larly described  in  the  account  of  the  ear. 

THE  GLOSSO-PHARYNGEAL,  OR  NINTH  PAIR  OF  NERVES. 

The  Glosso-pharynge'al  nerves2  arise  by  about  a  half  dozen  cords 
from  the  restiform  body,  just  behind  the  olivary  body.  They  issue  from 
the  cavity  of  the  cranium,  in  company  with  the  pneumogastric  and 
accessory  nerves,  through  the  jugular  foramen. 

Within  the  latter  foramen,  some  of  the  fibres  of  the  glosso-pharyngeal 
nerve  become  mingled  with  nerve  cells,  forming  a  small  ganglion,3  but 
its  presence  is  inconstant. 

As  it  emerges  from  the  jugular  foramen,  the  glosso-pharyngeal  nerve 


1  Nervi    auditor!!.     Sing.:    n.  audito-  tatorius  linguae;  n.  lingualis  paris  oc- 
rius ;  n.  acusticus;   portio  mollis  paris  tari;  n.  lingualis  paris  noni;  n.  lingua- 
septirni,  or  nervi  auditorii;  portio  mollis  lis  pneumogastrici ;  first  branch  of  the 
nerve  :  portio  mollis  of  the  seventh  pair  eighth  pair  of  nerves. 

of  nerves ;  acoustic  nerve.  3  Ganglion  superius  nervi  glosso-pha- 

2  N.   glosso-pharyngei ;    par   nonum.  ryngei;  g.  jugulare  superius  ;  g.  Ehren- 
Sing.:  n.  pharyngo-glossus;  n.  lingualis  ritteri;  g.  Miilleri;  ganglion  of  Ehren- 
lateralis;    n.  sensualis  linguae;    n.  gus-  ritter. 


enlarges  into  the 


SYSTEM. 

)trous  ganglion,1  which  is  connected  by  fine  filaments 

with  the  pneumogastric 
sympathetic  nerves, 
an  import- 
tympanic  nerve? 
ascends  through  a  fine^ 
canal  of  the  petrous  por- 
tion of  the  temporal  bone 
to  the  tympanum,  and  ex- 
pands upon  the  promon- 
tory into  a  number  of 
branches,  which  supply 
the  lining  membrane  of 
the  tympanum,  the  round 
and  o'val  windows,  and 
the  Eustachian  tube.  It 
is.  also  connected  with  the 
sympathetic  plexus  of  the 
internal  carotid  artery, 
witfi  the  smaller  pe- 
il  nerve. 

Frtfrn  the  petrous  gan- 
glion, the  glosso-pharyn- 

THE  LAST  FOUR  CEREBRAL  NERVES,  THE  FACIAL  NERVE,  THE  SYMPA-       gCal         UCrVC         paSSCS        bC- 

THETIC,  AND  THE  VPPER  TWO  CERVICAL  NERVES.    1,  facial  nerve ;  2',  tween     the      jugular     Vein 
anastomosis  between  branches  of  the  facial  and  glosso-pharyngeal 

nerve;   2,  glosso-pharyngeal;   3,  pneumogastric ;  ^4  accessory,  5,  ^nd    the    internal    CarOti(^ 
hypoglossal;  6,  first  cervical  ganglion  of  the  sympathetic;  7,  first^  arterV    and  descends    in  a 
and  second  cervical  nerves;  8,  carotid  plexus  of  the  sympathetic  ,,     , 

on  the  internal  carotid  artery;  9,  tympanic  nerve  from  the  p»trous  CUrVC   TO   the    TOOt    01    the 

ganglion  of  the  glosso-oharyngeal ;   10,  its  connection  with  the  tongUC,      On      the      inner 
carotid  plexus;  11. Ip-anch  to  the  Eustachian  tube;  12,13,  branches        .-,     .    »'\i          *     i         i 

.to  the  round  and^oval  windows-of  the  ear;  14,  15,  branches  join-  S1Cl'  pliaryn- 

ing  the  small  and  greater  petrosal  nerves;  16,  otic  ganglion ;  17,  geal  niUSCle,  and    beneath 

auricular  branch  from  the  jugular  ganglion,  connected  by  fila-  1-1       .          -i         j      •, 

ments  with  the  petrous  ganglion  and  tfie  facial  nerve;  18,  anas-  ] 

tomosis  of  the  accessory  with  the  pneumogastric;  19,  anastomosis  *  it  is  Connected  by 

•of  the  first  cervical  nerve  with  <he  hypoglossal;  20,  anastomosis  mo^Jc    filaments    with    the 
of  the  second  cervical  nerve  with  a  branch  of  the  accessory ;  21, 

pharyngeal  plexus^  22,  superior  laryngeal  nerve;  23,  its  external  pneumogastric   nerve  and 

branch ;  £4,  second  cervical  ganglion  of  the  sympathetic.  ^Qe  carotid   pleXUS  of  the 

sympathetic,  and  gives  branches  to  the  .muscles*  and  mucous  membrane 


1  G.  inferius  nervi  glosso-phairyngei  ; 
g.  pelrosum  ;  g.  Anderschii  ;  neurono- 
dus  petrosus  ;  ganglion  of  Andersch. 


2  Nerve  of  Jacobson  ;  ramus  tympani- 
•  cus  ;  nervus  tympanicus   superior  ;   ra- 
mus  anastomoticus  Jacobsonii;  nervus 
Jacobsonii. 


THE  NERVOUS  SYSTEM.  555 

of  the  pharynx.  '  Its  terminal  brashes  are  distributed  to  the  tonsils  and 
the  mucous  membrane  of  the  root  of  the  tongue,  including  the  circum- 
vallate  papillae. 

Tne  glosso-pharyngeal  nerve  is  sensory-motor  in  its  function;  and 
its  terminal  branches  are  by  many  believed  to  participate  with  the  lingual 

nerve  in  the  sense  of  taste. 
•  • 

THE  PNEUMOGASTRIC,  OR  TENTH  PAIR  OF  NERVES. 

The  Pneumogas'tric  nerves1  extend  from  the  cavity  of  the  cranium, 
through  the  neck  and  thorax,  into  the  abdomen,  and  .are  distributed  to 
the  organs  of.  voice  and  respiration,  the  heart,  and  the  alimentary  canal 
from  the  pharynx  to  the  stoiflach  inclusively.  They  spring  by  from  ten 
to  fifteen  cords  from  the  groove  behind  the  olivary  body,  and  pass  from 
the  cranium,  in  company  with  the  glosso-pharyngeal*  and 
nerves,  through  the  jugular  foramen.  From  thfince  they  descend 
the  sheath  of  the  great  blood-vessels*  of  the  neck,  lying  posteriorly  be- 
tween the  carotid  arteries  and  jugular  vein. 

At  the  bottom  of  the  neck  the  right  pneumogastric  nerve  enters  the 
posterior  mediastinal  cavity  batween  the  corresponding  subclavian  artery 
and  vein.  Jt  then  descends  behind  the  root  of  the  right  lung  to  the  pos- 
terior surfiR  of  the  esophagus,  which  it  accompanies  to  the  stomach. 

The  left  pneumogastric  nerve  descends,  in  front  of  the  left  subclavian 
artery  and  the  arch  of  the  aorta,  into  the  posterior*  mediastinal  cavity, 
and  passes  behind  the  root  of  the  left  lung  to  the  front  of  the  oesopha- 
gus, along  which  it  continues  to  the  stomach. 

Within  the  jugular  foramen  the  pneumogastric  nerve  presents  an 
ovoidal,  grayish  body,  the  jugular  ganglion.2  This  resembles  in  appear- 
arice  the  ganglia  of  the  spinal  nerves,  and  like  them  it  gives  additional 
fibres  to  the  trunk  upon  which  it  is  situated.  It  gives  off  an  auricular 
branch,3  which,  after  being  joined  by  filaments  from  the 'petrous  gan- 
glion  and  the  facial  nerve,  is  distributed  to  the  external  auditory  meatus. 
t  Having  emerged  from  the  ^igular  foramen,  the  pneumogastric  nerve  re- 
ceives an  accession  of  fibres  from  the  accessory  and*hypoglossal  nerves,  and 
dilates  into  a  fusiform  enlargement  called  the  gangliform  plexus.4  This 

• 

1  "Nervi  pneu/nogastrici ;  par  vagum ;  3  Ramus  auricularis ;  auricular  nerve 
par  undeehnum.     Sing.:  nervus  vagus;       of  Arnold. 

n.  ambulatoriuk ;  n.  decimus  ;  n.  sym-  *  Plexus  gangliformls ;  p.  nodosus  ; 
patheticus  medius ;  second  branch  of  ganglion  inferfus  nervi  vagi ;  g.  tunici 
the  eighth  pair  of  nerves.  .  nervi  vagi. 

2  G.  JHg-ulare  nervi  vagi;  g.  superius 
nervi  vagi ;  g.  nervi  vagi. . 


556 


THE   NERVOUS   SYSTEM. 


is  about  three-fourths  of  an  inch  long,  of  comparatively  loose  texture, 
and  contains  mingled  nerve  cells. 


FIG.  340. 


THE  PNEUMOGASTRIC  NERVE.  1,  trunk  of  the  pneurnogastric;  2,  gangliform  plexus;  3,  anastomosis  of 
the  latter  with  the  accessory  nerve ;  4,  anastomosis  with  the  hypoglossal ;  5,  pharyngeal  nerve ;  6,  supe- 
rior laryngeal  nerve;  7,  its  external  branch;  8,  pharyngeal  plexus;  9,  inferior  laryngeal  nerve;  10,  11, 
filaments  to  the  cardiac  plexus;  12,  commencement  of  the  cesophageal  plexus;  13,  pulmonary  plexus; 
14,  lingual  nerve;  15,  lower  part  of  the  hypoglossal  nerve;  16,  glosso-pharyngeal  nerve;  17,  accessory 
nerve;  18, 19,  20,  second,  third,  and  fourth  cervical  nerves;  21,  commencement  of  the  phrenic  nerve;  22, 
23,  the  lower  four  cervical  nerves  which  with  the  first  thoracic  nerve  form  the  brachial  plexus;  24,  25, 
first  and  second  cervical  ganglia  of  the  sympathetic;  26,  third  cervical  united  with  the  first  thoracic 
ganglion ;  27-30,  second  to  the  fifth  thoracic  ganglia. 

The  gangliform  plexus  receives  anastomotic  branches  from  the  glosso- 
pharyngeal  nerve,  the  first  cervical  ganglion  of  the  sympathetic,  and  the 
upper  part  of  the  cervical  plexus,  and  it  gives  off  the  pharyngeal  and 
superior  laryngeal  nerves. 


THE   NERVOUS   SYSTEM.  557 

The  Pharynge'al  nerve  or  nerves,1  from  one  to  three  in  number,  de- 
scend upon  the  side  of  the  pharynx,  anastomose  with  the  pharyngeal 
branches  of  the  glosso-pharyngeal  nerve,  and  supply  the  constrictor 
muscles  and  mucous  membrane  of  the  pharynx. 

The  Superior  Larynge'al  nerve2  curves  downward  and  forward  to  the 
side  of  the  larynx.  After  giving  a  branch  to  the  inferior  constrictor  of 
the  pharynx,  the  crico-thyroid  muscle,  and  the  thyroid  body,  it  pierces 
the  thyro-hyoid  membrane,  and  is  expended  in  numerous  filaments  to  the 
mucous  membrane  of  the  larynx. 

Descending  the  neck,  the  pneumogastric  nerve  gives  off  several  fila- 
ments3 which  join  the  cardiac  nerves  of  the  sympathetic,  or  descend  the 
neck  to  the  cardiac  plexus.  It  also  gives  off  an  anastomotic  branch 
to  the  descending  cervical  nerve  of  the  hypoglossal.  At  the  bottom 
of  the  neck  it  gives  off  a  large  branch,  the  Inferior  Larynge'al  nerve.4 
This,  on  the  right  side,  descends  in  front  of  the  subclavian  artery, 
and  winds  around  it  posteriorly  from  beneath ;  on  the  left  side,  in  the 
same  manner,  the  nerve  winds  around  the  arch  of  the  aorta.  It  then 
ascends  the  neck,  in  the  interval  laterally  of  the  trachea  and  oesophagus, 
to  the  larynx.  In  its  course  it  is  connected  by  anastomotic  filaments 
with  the  last  cervical  ganglion,  and  the  cardiac  plexus  of  the  sympa- 
thetic, and  gives  branches  to  the  trachea  and  oesophagus.  Its  terminal 
branches  supply  most  of  the  muscles  of  the  larynx,  a  few  of  them  being 
distributed  to  the  mucous  membrane,  and  anastomosing  with  the  superior 
laryngeal  nerve. 

In  the  thorax  the  pneumogastric  nerve  gives  off  cardiac  and  pulmo- 
nary branches,  and  then  with  its  fellow  forms  the  cesophageal  plexus. 

The  cardiac  branches5  are  derived  from  the  pneumogastric  nerve  be- 
low the  inferior  laryngeal.  They  anastomose  with  the  cardiac  branches 
of  the  sympathetic,  and  contribute  to  form  the  cardiac  plexus  of  the 
latter. 

The  pulmonary  branches6  are  numerous,  and  enter  the  root  of  the 
lung  upon  the  bronchus,  a  few  in  front,  but  mainly  at  its  back  part. 
They  are  joined  by  filaments  from  the  upper  thoracic  ganglia  of  the 
sympathetic,  and  form  on  the  bronchus  the  pulmonary  plexus,7  from 

1  Nervi  pharyngei.  5  Rami  cardiaci;   r.  c.  profundi  infe- 

2  Nervus  laryngeus  superior.  riores. 

3  Rami  cardiaci.  «  Rami  pulmonarii. 

4  Nervus  laryngeus  inferior,  or  recur-  7  Plexus  pulmonalis  anterior  et  poste- 
rens ;  recurrent  laryngeal  nerve.  rior. 


558  THE   NERVOUS   SYSTEM. 

which  the  nerves  follow  the  ramifications  of  the  bronchial  tubes  through- 
out the  lungs. 

Afterfthe  origin  of  the  pulmonary  branches,  the  pneumogastric  nerve 
of  the  right  side  applies  itself  to  the  back  of  the  oesophagus,  while  that 
of  the  left  side  applies  itself  to  the  front.  By  division  and  reunion  of 
branches,  the  two  nerves  form  the  intricate  cesophage'al  plexus,1  which 
surrounds  the  oesophagus  and  supplies  its  walls. 

The  terminal  branches2  of  the  right  pneumogastric  nerve,  after  leav- 
ing the  oesophageal  plexus,  are  distributed  to  the  posterior  part  of  the 
stomach,  and  are  connected  with  the  solar  plexus  of  the  sympathetics. 

The  terminal  branches2  of  the  left  pneumogastric  nerve,  descending 
from  the  oesophagus,  supply  the  front  surface  and  pyloric  extremity  of 
the  stomach,  and  partly  proceed  along  its  lesser  curvature  to  join  the 
hepatic  plexus  of  the  sympathetics. 

The  pneumogastric  nerve  is  sensory- motor  in  its  function,  and  presides 
over  the  general  sensibility  and  muscular  actions  of  the  pharynx,  oesoph- 
agus, stomach,  larynx,  trachea,  and  lungs. 

* 

THE  ACCESSORY,  OR  fDEELFTII  PAIR  OF  NERYES. 

The  Accessory  nerves3  are  somewhat  variable  in  extent  and  origin, 
and  not  unfrequently  differ  on  the  two  sides.  They  arise  by  a  series  of 
filaments  from  the  lateral  columns  of  the  spinal  cord,  and  from  the  med- 
ulla oblongata,  below  and  behind  the  olivary  bodies.  The  filaments  of 
origin  may  commence  as  low  as  from  the  third  to  the  last  cervical  verte- 
bra, and  are  situated  between  the  posterior  roots  of  the  spinal  nerves 
and  the  denticulated  ligament.  They  are  successively  collected  into  an 
ascending  cord,  which  enters  the  cranium  through  the  occipital  foramen. 
The  accessory  nerve  then  passes  through  the  jugular  foramen,  in  com- 
pany with  the  glosso-pharyngeal  and  pneumogastric  nerve,  and  divides 
into  two  branches.  One  of  these  joins  the  gangliform  plexus  of  the 
pneumogastric  nerve ;  the  other  branch  turns  outwardly  behind  the  jugu- 
lar vein,  and  pierces  the  sterno-mastoid  muscle  above  its  middle.  After 
supplying  the  latter  with  filaments,  it  proceeds  through  the  supra-clavic- 
ular fossa  to  the  trapezius  muscle,  in  which  it  terminates. 

Besides  its  connection  with  the  pneumogastric,  the  accessory  nerve 
anastomoses  with  the  upper  four  cervical  nerves.  Occasionally  it  pre- 

1  Plexus  oesophageus.  of  the  par  vagum,  or  eighth  pair ;  ner- 

2  Kami  gastrici.  vus  accessorius  Willisii ;  n.  a.  ad  par  oc- 
8  Spinal  accessory  nerves;  nervi  ac-      tavum;  n.  spinalis;  superior  respiratory 

cessorii ;  par  undecimum  ;  eleventh  pair      nerve ;  third  branch  of  the  eighth  pair 
of  encephalic  nerves.    Sing. :  accessory      of  nerves. 


THE   NERVOUS   SYSTEM.  559 

sents  a  ganglion  upon  its  trunk.    In  function  it  is  a  motor  nerve,  though 
it  appears  also  to  contain  a  few  sensory  fibres. 

THE  HYPOGLOSSAL,  OR  TWELFTH  PAIR  OF  NERYES. 

The  Hypoglos'sal  nerves,1  the  last  pair  of  the  cerebral  series,  arise  by 
a  number  of  filaments  from  the  fissure  between  the  pyramidal  and  olivary 
bodies.  The  filaments  converge  into  two  bundles,  which,  after  passing 
through  the  condyloid  foramen  of  the  occipital  bone,  unite  in  a  rounded 
cord. 

From  the  condyloid  foramen  the  hypoglossal  descends  behind  the 
pneumogastric  nerve,  and  then  curves  downward  and  forward  to  the 
outer  side  of  the  latter,  between  the  internal  carotid  artery  and  jugular 
vein,  to  the  under  part  of  the  tongue.  It  is  here  situated  above  the 
hyoid  bone,  on  the  outer  side  of  the  hyo-glossal  muscle,  and  penetrates 
the  genio-glossal  muscle,  to  which,  and  the  other  muscular  structure  of 
the  tongue,  it  is  distributed. 

After  its  exit  from  the  cranium,  the  hypoglossal  nerve  is  connected  by 
anastomotic  filaments  with  the  first  cervical  ganglion  of  the  sympathetic, 
the  gangliform  plexus  of  the  pneumogastric,  and  the  upper  two  cervical 
nerves.  Lower  in  its  course  it  gives  off  the  descending  cervical  nerve,2 
which  crosses  to  the  outer  side  of  the  great  blood-vessels  of  the  neck, 
and,  after  being  joined  by  filaments  from  the  pneumogastric  and  cervical 
plexus  of  nerves,  is  distributed  to  the  omo-hyoid,  sterno-hyoid,  and 
sterno-thyroid  muscles. 

The  hypoglossal  nerve,  as  indicated  by  its  distribution,  is  motor  in 
function. 

THE  SPINAL  NERYES. 

Of  Spinal  nerves3  there  are  thirty-one  pairs,  divided,  according  to 
their  relation  with  the  vertebral  column,  into  eight  cervical,  twelve  tho- 
racic, five  lumbar,  five  sacral,  and  one  coccygeal  nerve. 

Every  spinal  nerve  originates  by  an  anterior  and  a  posterior  root  from 
the  corresponding  lateral  grooves  of  the  spinal  cord.  Each  root  is  com- 
posed of  a  vertical  series  of  flattened  threads,  which  converge  together 
from  their  origin.  The  anterior  roots,  except  those  of  the  upper  two 
cervical  nerves,  are  larger  and  composed  of  a  greater  number  of  threads 
than  the  posterior  roots. 

1  Nervi  hypoglossi ;  par  nonum ;  ninth  2  Descendens  noni ;  ramus  descendens. 
pair  cf  nerves.  Sing. :  nervus  lingualis  ;  3  Vertebral  nerves  ;  intervertebral 

n.  1.  medius ;    n.  motorius  linguae ;    n.       nerves, 
sublingualis  ;  n.  loqueus  ;  hypoglossus  ; 
myoglossus ;  gustatory  nerve. 


560  THE   NERVOUS   SYSTEM. 

The  largest  roots  of  the  spinal  nerves  are  those  of;  the  lower  four  cer- 
vical and  the  first  thoracic  nerve,  which  supply  the  upper  extremities ; 
and  those  of  the  lower  three  lumbar  and  upper  two  sacral  nerves,  which 
supply  the  lower  extremities. 

The  anterior  and  posterior  roots  converge  and  pass  side  by  side 
through  separate  apertures  of  the  dura  mater,  opposite  the  intervertebral 
and  sacral  foramina,  but  are  accompanied  by  tubular  sheaths  of  that 
membrane. 

In  consequence  of  the  comparative  shortness  of  the  spinal  cord,  the 
roots  of  the  spinal  nerves,  in  order  to  reach  their  place  of  exit  from  the 
dura  mater,  successively  increase  in  length  from  the  first  to  the  last. 
From  this  arrangement  they  also  incline  more  and  more  from  a  horizon- 
tal course,  until  they  finally  assume  a  vertical  direction,  and  thus  the 
roots  of  the  lumbar,  sacral,  and  coccygeal  nerves  are  collected  into  a 
thick  bundle1  occupying  the  lower  part  of  the  sheath  of  the  dura 
mater. 

The  posterior  roots  of  the  spinal  nerves  are  provided  with  a  reddish- 
gray,  oval  ganglion,  which  contributes  additional  fibres  to  the  roots  as 
they  proceed  from  them.  The  ganglia,  except  those  of  the  sacral  and 
coccygeal  nerves,  are  situated  within  the  intervertebral  foramina.  Those 
of  the  sacral  nerves  are  contained  within  the  spinal  canal,  and  that  of 
the  coccygeal  nerve  is  even  placed  within  the  sheath  of  the  dura  mater 
of  the  spinal  cord. 

The  anterior  root  of  the  spinal  nerves  lies  in  contact  with  the  ganglion 
of  the  posterior  root,  but  neither  contributes  to  nor  receives  fibres  from 
it.  Immediately  beyond  the  ganglion,  the  two  roots  unite  in  a  common 
trunk,  which  is  a  short,  rounded  cord,  composed  of  an  intermixture  of 
the  nerve  fibres  of  both  roots. 

The  spinal  nerves  thus  formed  emerge  from  the  intervertebral  fora- 
mina, the  sacral  and  coccygeal  nerves  excepted,  which  divide  within  the 
vertebral  canal  into  anterior  and  posterior  branches,  and  then  escape 
through  the  corresponding  sacral  foramina. 

The  nerves  which  pass  through  the  intervertebral  foramina  imme- 
diately afterwards  divide  into  an  anterior  and  a  posterior  branch.  With 
the  exception  of  those  of  the  first  two  pairs  of  spinal  nerves,  the  anterior 
branches  are  much  the  larger,  and  are  destined  to  supply  the  trunk  in 
advance  of  the  vertebral  column,  and  the  limbs ;  the  posterior  branches 
are  distributed  to  the  back  of  the  trunk. 

The  anterior  roots  of  the  spinal  nerves  are  motor  in  function  ;  the 
posterior  roots  are  sensory.  The  association  of  the  two  roots  renders 

1  Cauda  equina. 


THE  NERVOUS   SVSTEM.  561 

the  spinal  nerves  sensory-motor ;  and  with  this  endowment  the  nerves 
are  distributed  to  the  muscles  and  skin  of  the  body,  from  the  head 
downward. 

THE  CERVICAL  NERVES. 

Of  the  Cer'vical  nerves1  there  are  eight  pairs,  of  which  the  first 
pair,  or  suboccip'ital  nerves,2  emerge  from  the  vertebral  canal,  between 
the  occipital  bone  and  atlas ;  and  the  last  pair  escape  through  the  inter- 
vertebral  foramina,  between  the  last  cervical  and  first  dorsal  vertebra. 
They  increase  successively  from  above  downward,  and,  after  passing 
from  the  vertebral  canal,  as  already  indicated,  they  divide  into  an  ante- 
rior and  a  posterior  branch. 

POSTERIOR  BRANCHES  OF  THE  CERVICAL  NERVES. 

The  posterior  branch  of  the  first  cervical,  or  suboccip'ital  nerve,2  is 
larger  than  the  anterior  branch.  After  issuing  from  between  the  arch 
of  the  atlas  and  the  vertebral  artery,  it  is  expended  in  filaments  on  the 
contiguous  straight,  oblique,  and  complex  muscles ;  one  of  them  de- 
scending to  communicate  with  the  second  cervical  nerve. 

The  posterior  branch  of  the  second  cervical  nerve  is  the  largest  of 
the  corresponding  branches  of  the  cervical  series.  Emerging  from 
between  the  arches  of  the  atlas  and  axis,  it  receives  a  communicating 
filament  from  the  first  cervical  nerve,  and  then  divides  into  two  branches. 
Of  these,  the  external  branch  is  expended  in  the  complex,  splenius,  and 
trachelo-mastoid  muscles.  The  internal  branch,  or  great  occipital 
nerve,3  pierces  the  complex  and  trapezius  muscles,  and  accompanies  the 
occipital  artery  to  be  distributed  to  the  muscle  and  skin  of  the  occipital 
region. 

The  posterior  branches  of  the  lower  six  cervical  nerves,  after  pass- 
ing backward  between  the  transverse  processes  of  the  vertebrae,  divide 
into  external  and  internal  branches. 

The  external  branches  supply  the  ascending  cervical,  transverse  cer- 
vical, and  trachelo-mastoid  muscles.  The  internal  branches  are  larger 
than  the  preceding.  These,  from  the  third,  fourth,  and  fifth  cervical 
nerves,  turn  inwardly  toward  the  spinous  processes  of  the  vertebrae,  and 
are  then  directed  outwardly  to  be  distributed  to  the  skin ;  while  those 
from  the  lower  three  cervical  nerves  terminate  in  the  complex,  semi- 
spinal,  and  multifid  spinal  muscles. 

1  Nervi  cervicales:  n.  cervicis ;  n.  nuchse  ;  n.  intervertebrales  colli. 

2  N.  cervicalis  primus ;    n.  c.  supremus  ;  n.  infra-occipitalis. 

3  N.  occipitalis  magnus  or  maximus. 

36 


562  THE   NERVOUS   SYSTEM. 


ANTERIOR  BRANCHES  OF  THE  CERVICAL  NERVES. 

The  anterior  branches  of  the  cervical  nerves  successively  increase  in 
size  from  first  to  last.  They  turn  forward  to  the  outer  side  of  the  verte- 
bral artery,  except  the  first  of  the  series,  which  is  situated  beneath  the 
horizontal  turn  of  that  vessel  above  the  atlas. 

The  anterior  branches  of  the  upper  four  cervical  nerves  divide  and 
anastomose  with  one  another  in  such  a  manner  as  to  form  a  series  of 
loops,  constituting  the  cervical  plexus,  which  is  situated  in  front  of  the 
attachment  of  the  muscles  to  the  transverse  processes  of  the  vertebras. 
The  plexus  is  connected  by  anastomotic  filaments  with  the  superior  cer- 
vical ganglion  and  trunk  of  the  sympathetic,  and  with  the  pneumogas- 
tric,  accessory,  and  hypoglossal  nerves.  It  supplies  an  offset  to  the 
brachial  plexus,  and  gives  off  numerous  branches,  which  are  mainly  dis- 
tributed to  the  front  and  side  of  the  neck. 

The  anterior  branches  of  the  lower  four  cervical  nerves  are  much 
larger  than  the  preceding.  Through  anastomosis  together,  and  with  the 
anterior  branch  of  the  first  thoracic  nerve,  they  form  the  brachial 
plexus,  mainly  destined  to  supply  the  upper  extremity.  The  nerves 
forming  the  brachial  plexus  communicate  by  filaments  with  the  second 
and  third  cervical  and  first  dorsal  ganglia  of  the  sympathetic. 

THE  CERVICAL  PLEXUS. 

The  Cer'vical  plexus,1  as  above  mentioned,  is  formed-  by  division  and 
anastomosis  of  the  anterior  branches  of  the  upper  four  cervical  nerves. 
It  is  situated  beneath  the  sterno-mastoid  muscle,  and  rests  upon  the 
middle  scalene  muscle  and  the  elevator  of  the  scapular  angle,  opposite 
the  upper  four  cervical  vertebrae. 

From  the  cervical  plexus  are  derived  the  following  nerves  : — 

1.  Muscular  branches. 

2.  The  superficial  cervical  nerve. 

3.  The  great  auricular  nerve. 

4.  The  small  occipital  nerve. 

5.  The  supra-clavicular  nerves. 

6.  The  phrenic  nerve. 

1.  The  Muscular  branches  supply  the  scalene  and  long  cervical  mus- 
cles, the  anterior  and  lateral  straight  muscles,  the  elevator  of  the  scap- 
ular angle,  and  the  sterno-mastoid  and  trapezius  muscles. 

1  Plexus  cervicalis. 


THE   NERVOUS   SYSTEM.  563 

2.  The  Superficial  Cer'vical  nerve,1  derived  from  the  anastomosis  of 
the  second  and  third  cervical  nerves,  is  directed  around  the  posterior 
border  of  the  sterno-mastoid  muscle,  and  passes  forward  between  it  and 
the  subcutaneous  cervical  muscle.    Dividing  into  ascending  and  descend- 
ing branches,  the  former  supply  the  subcutaneous  cervical  muscle  and 
the  skin  at  the  upper  fore  part  of  the  neck,  and  anastomose  with  fila- 
ments of  the  facial  nerve ;  the  latter  supply  the  skin  of  the  lower  fore 
part  of  the  neck. 

3.  The   Great  Auric'ular  nerve,2  from  the  cervical   plexusf  winds 
around  the  posterior  border  of  the  sterno-mastoid  muscle,  and  ascends 
on  its  outer  surface  to  be  distributed  to  the  external  ear  and  the  skin 
over  the  parotid  gland  and  mastoid  process.     Some  of  its  filaments 
anastomose  with  branches  of  the  facial  and  pneumogastric  nerves. 

4.  The  Small  Occip'ital  nerve,3  derived  from  the   second  cervical 
nerve,  ascends  along  the  posterior  border  of  the  sterno-mastoid  muscle, 
and  is  distributed  to  the  skin  and  muscles  of  the  occipital  region,  anas- 
tomosing with  the  great  occipital  and  great  auricular  nerves. 

5.  The  Supra-clavic'ular  nerves,4  of  which  there  are  usually  three, 
spring  from  the  fourth  cervical  nerve,  and  descend  in  the  interval  of  the 
sterno-mastoid  and  trapezius  muscles  to  be  distributed  to  the  skin  over 
the  clavicle,  the  breast,  and  shoulders. 

6.  The  Phrenic  nerve,5  the  most  important  branch  of  the  cervical 
plexus,  springs  from  the  third  and  fourth  cervical  nerves,  and  further 
receives  an  offset  from  the  fifth  cervical  nerve  or  the  commencement  of 
the  brachial  plexus.     Descending  upon  the  anterior  scalene  muscle,  it 
enters  the  thorax  between  the  subclavian  artery  and  vein,  and  proceeds 
downward  in  front  of  the  root  of  the  lung,  included  between  the  pleura 
and  pericardium  until  it  reaches  the  diaphragm,  to  which  it  is  distributed. 
In  its  course  it  receives  anastomotic  filaments  from  the  lower  two  cervical 
ganglia  of  the  sympathetic,  and  gives  filaments  to  the  pericardium. 

THE  BRACHIAL  PLEXUS. 

The  Bra'chial  plexus,6  which  mainly  supplies  the  upper  extremity,  is 
formed  through  anastomosis  of  the  anterior  branches  of  the  lower  four 

1  N.  superficialis  colli;  n.  subcutane-  4  N.  supra-claviculares;  n.  s.  c.  anteri- 
ous  colli  superior,  medius,  et  infimus.  ores,  medii,  et  posteriores. 

2  N.  auricularis   magnus ;    n.  a.  pos-  5  N.  phrenicus ;    n.  diaphragmaticus  ; 
terior.  n.  respiratorius  internus  ;   internal  res- 

8  N.  occipitalis  minor.  piratory  nerve  of  Bell. 

6  Plexus  brachiales  ;  p.  axillaris. 


564 


THE   NERVOUS   SYSTEM. 


cervical  nerves,  together  with  the  corresponding  branch  of  the  first  tho- 
racic nerve.  It  extends  from  the  side  of  the  cervical  vertebrae  to  the 
axilla,  and  opposite  the  coracoid  process  separates  into  large  offsets  for 
the  upper  extremity.  In  its  course  it  passes  outwardly  between  the  an- 
terior and  middle  scalene  muscles,  and  descends  obliquely  beneath  the 

FIG.  341. 


THE  BRACHIAL  PLEXUS.  1,  anastomosis  between  the  descending  cervical  branch  of  the  hypoglossal  and 
a  branch  of  the  cervical  plexus;  2,  pneumogastric  nerve;  3,  phrenic  nerve;  4-8,  the  lower  four  cervical, 
and  the  first  thoracic  nerves,  forming  the  brachial  plexus;  9.  branch  to  the  subclavian  muscle  giving  a 
filament  to  the  phrenic  nerve ;  10,  posterior  thoracic  nerve ;  11, 13,  anterior  thoracic  nerves ;  14,  anasto- 
mosis between  the  latter;  12,  supra-scapular  nerve;  15-17,  subscapular  nerves;  18,  small  cutaneous 
nerve;  19,  anastomosis  of  a  branch  of  the  latter  with  the  intercosto-humeral  nerve,  20;  21,  continuation 
of  the  small  cutaneous  nerve  in  company  with  the  internal  cutaneous,  22;  23,  ulnar  nerve;  24,  median; 
25.  external  cutaneous ;  26,  musculo-spiral  nerve. 

clavicle  into  the  axilla.  It  is  at  first  situated  above  and  partially  be- 
hind the  subclavian  blood-vessels,  then  behind  the  axillary  vessels,  and 
finally,  it  surrounds  the  latter  as  it  is  about  to  expend  itself  in  branches. 
In  its  modes  of  formation  the  brachial  plexus  is  subject  to  variation, 
but  the  most  frequent  arrangement  is  that  which  follows.  The  fifth  cer- 


THE   NERVOUS   SYSTEM  565 

vical  nerve  descends  obliquely  and  joins  the  sixth,  and  the  trunk  thus 
formed  is  shortly  after  joined  by  the  seventh  cervical  nerve.  The  first 
thoracic  nerve  ascends  obliquely  to  join  the  eighth  cervical  nerve.  The 
two  trunks  thus  produced  then  send  off  each  a  branch  which  joins  with 
its  fellow  to  form  a  third  trunk.  Of  the  three  trunks,  one  is  placed  on 
the  outer  side  of  the  axillary  artery ;  another  on  the  inner  side ;  and 
the  third  behind  the  vessel ;  and  from  them  diverge  the  branches  to  the 
limb. 

The  branches  given  off  from  the  brachial  plexus  above  the  clavicle 
are,  for  the  most  part,  destined  to  supply  the  side  of  the  thorax  and 
shoulder ;  those  given  off  below  the  clavicle  are  its  terminal  divisions, 
and  mostly  extend  the  length  of  the  upper  extremity. 

The  branches  of  the  brachial  plexus  are  as  follow : — 

1.  Muscular  branches. 

2.  Supra-scapular  nerve. 

3.  Thoracic  nerves. 

4.  Subscapular  nerves. 

5.  Small  cutaneous  nerve. 

6.  Internal  cutaneous  nerve. 

7.  External  cutaneous  nerve. 

8.  Circumflex  nerve. 

9.  Median  nerve. 

10.  Ulnar  nerve. 

11.  Musculo-spiral  nerve. 

1.  The  Muscular  branches  given  off  from  the  commencement  of  the 
brachial  plexus   supply  the  scalene,  long  cervical,  rhomboid,  superior 
serrate,  and  subclavian  muscles. 

2.  The  Supra-scap'ular  nerve,1  from  the  upper  trunk  of  the  brachial 
plexus,  passes  outward  and  backward,  and  proceeds  through  the  supra- 
scapular  foramen  to  supply  the  supra-  and  infra-spinous  muscles. 

3.  The  Thorac'ic  nerves  consist  of  posterior  and  anterior  branches. 
The  posterior  or  long  thoracic  nerve,2  larger  than  the  others,  is  derived 
from  the  fifth  and  sixth  cervical  nerves,  and  descends  along  the  fore  part 
of  the  great  serrated  muscle,  to  which  it  is  distributed.     The  anterior 
thoracic  nerves,3  of  which  there  are  two,  spring  from  the  inner  and 
outer  trunks  of  the  brachial  plexus,  and  pass  beneath  the  clavicle  to 
supply  the  pectoral  muscles. 

1  N.  supra-scapularis;  n.  scapularis. 

2  N.  thoracicus  posterior,  or  longus;  n.  respiratorius  externus;  external  respira- 
tory nerve  of  Bell. 

8  Nervi  thoracic! ;  n.  pectorales  anteriores. 


566  THE   NERVOUS   SYSTEM. 

4.  The  Subscap'ular  nerves,1  of  which  there  are  three,  originate  by 
filaments  from  all  the  cords  of  the  brachial  plexus,  except  the  first  tho- 
racic nerve.     The  largest  branch  descends  along  the  outer  border  of 
the  subscapular  muscle  to  be  distributed  to  the  latissimus  muscle,  some 
of  its  filaments  reaching  the  inferior  serrated  muscle.     The  other  two 
nerves  enter  the  upper  part  of  the  subscapular  and  terete  muscles,  which 
they  supply. 

5.  The  Small  Cuta'neous  nerve,2  derived  from  the  first  thoracic  nerve 
of  the  brachial  plexus,  descends  along  the  inner  side  of  the  axillary  and 
brachial  blood-vessels  to  near  the  middle  of  the  arm.     It  then  pierces 
the  fascia  of  the  latter,  and  proceeds  beneath  the  skin  to  the  elbow  be- 
tween the  internal  condyle  and  olecranon.     In  its  course  it  anastomoses 
with  the  intercosto-humeral  nerve,  and  it  supplies  the  skin  on  the  lower 
inner  part  of  the  arm. 

The  remaining  branches  of  the  brachial  plexus  come  off  at  the  lower 
or  outer  part  of  the  axilla,  and  appear  as  its  terminal  divisions,  for  the 
most  part  extending  the  length  of  the  upper  extremity. 

6.  The  Internal  Cuta'neous  nerve,3  from  the  lower  trunk  of  the  bra- 
chial plexus,  is  its  smallest  terminal  branch.     It  descends  on  the  inner 
side  of  the  brachial  blood-vessels,  near  the  middle  of  the  arm,  pierces 
the  fascia,  and  divides  into  two  branches.    Of  these  the  smaller  branch 
descends  to  the  inner  side  of  the  basilic  vein  and  behind  the  internal 
condyle,  to  be  distributed  to  the  skin  on  the  back  of  the  forearm.     The 
larger  branch,  apparently  the  continuation  of  the  main  nerve,  descends 
along  the  inner  front  part  of  the  arm  and  forearm,  and  is  expended  in 
the  contiguous  skin.     At  the  bend  of  the  elbow  one  of  its  branches 
usually  passes  above,  and  another  beneath  the  median  basilic  vein,  near 
the  termination  of  this  vessel  in  the  basilic  vein. 

7.  The  External  Cuta'neous  nerve,4  larger  than  the  preceding,  and 
derived  from   the  upper  cord  of  the  brachial  plexus,  perforates   the 
coraco-brachial  muscle,  and  passes  between  the  biceps  flexor  and  bra- 
chial muscle  to  the  outer  part  of  the  arm.       It  here  perforates  the 
brachial  fascia,  and  divides  into  two  branches,  of  which  one  passes  in 


1  N.  subscapulares.  3  N.  cutaneus  interims;    n.  c.  i.  ma- 

2  N.  cutaneus   minor;    n.    c.  internus      jor;  n.  c.  brachii  medius. 

minor;  n.  c.  brachii  internus;  n.  c.  ul-  4  N.  cutaneus   externus  ;   n.  musculo- 

naris  Wrisbergii.  cutaneus  ;  n.  perforans  Casserii ;  ramus 

magnus  nervi  mediani. 


THE   NERVOUS  SYSTEM. 


567 


front,  the  other  beneath  the  median  cephalic  vein,  and  both  descend 
along  the  outer  part  of  the  forearm  to  the  wrist. 


FIG.  342. 


FIG.  343. 


l    1 


CUTANEOUS  NERVES  OF  THE  UPPER  EXTREMITY.  1,  supra-clavicular  nerves  of  the  cervical  plexus;  2, 
cutaneous  branches  of  the  circumflex  nerve;  3,  branch  of  the  internal  cutaneous  nerve;  4,  small  cuta- 
neous nerve,  with  its  anastomosis  from  the  intercosto-humeral ;  5,  cutaneous  branch  of  the  musculo- 
spiral  nerve;  6,  internal  cutaneous  nerve  piercing  the  brachial  fascia;  7,  posterior  branch  anastomosing 
with  8,  the  ulnar  nerve,  and  9,  the  anterior  branch;  10,  the  internal  cutaneous  dividing  into  branchep, 
some  passing  in  front  and  others  behind  the  median  basilic  vein;  11,  external  cutaneous  nerve;  12, 
cutaneous  branch  of  the  musculo-spiral  nerve ;  13,  branches  of  the  internal  cutaneous  to  the  front  of  the 
forearm ;  14,  anastomosis  of  one  of  the  latter  branches  with  one  from  the  ulnar  nerve ;  15,  terminal 
branches  of  the  external  cutaneous  nerve;  16, 17,  anastomosis  between  the  latter  and  the  radial  nerve; 
18,  superficial  palmar  branch  of  the  median  nerve;  19-25,  digital  nerves. 

In  its  course  it  gives  branches  to  the  coraco-brachial,  biceps  flexor, 
and  brachial  muscles,  and  its  terminal  branches  supply  the  skin  on  the 
outer  part  of  the  forearm  —  some  of  them  anastomosing  with  filaments 
of  the  radial  and  musculo-spiral  nerves. 


568  THE   NERVOUS   SYSTEM. 

8.  The  Circumflex  nerve1  accompanies  the  posterior  circumflex  blood- 
vessels around  the  upper  extremity  of  the  humerus,  and  is  distributed 
to  the  lesser  terete  and  deltoid  muscles,  some  of  the  branches  also  sup- 
plying the  shoulder  joint  and  the  skin  on  the  back  of  the  arm. 

9.  The  Median  nerve2  commences  by  two  roots  embracing  the  axillary 
artery  from  the  inner  and  outer  trunks  of  the  brachial  plexus,  and  de- 
scends in  contact  with  the  brachial  artery  to  the  elbow.     Crossing  in 
front  of  the  latter,  the  nerve  passes  beneath  the  terete  pronator,  and 
proceeds  between  the  superficial  and  deep  flexors  of  the  fingers  to  the 
wrist,  and  then  passes  under  the  annular  ligament  to  the  palm  of  the 
hand.     In  its  course  it  gives  off  the  following  branches  : — 

i    a.  Muscular  branches  to  the  muscles  on  the  front  of  the  forearm, 
except  the  ulno-carpal  flexor. 

b.  The  anterior  interosseous  nerve,3  which  follows  the  corresponding 
artery,  and  supplies  the  deeper  muscles  on  the  front  of  the  forearm. 

c.  The  superficial  palmar  branch,4  which  pierces  the  fascia  of  the  fore- 
arm near  the  wrist,  and  proceeds  to  the  skin  of  the  palm  of  the  hand. 
vd.  A  muscular  branch  to  the  muscles  of  the  ball  of  the  thumb. 

e.  The  Digital  nerves,  of  which  there  are  five.  Two  proceed  to  the 
sides  of  the  thumb;  a  third  runs  along  the  outer  side  of  the  index 
finger ;  and  the  remaining  two  pass  down  the  second  and  third  meta- 
carpal  intervals,  and  divide  each  into  branches,  which  supply  the  con- 
tiguous sides  of  the  index,  middle,  and  ring  fingers.  The  fifth  digital 
nerve  receives  a  communicating  branch  from  the  ulnar  nerve. 

At  the  bases  of  the  first  phalanges,  the  digital  nerves  give  off  a  dor- 
sal branch,  which  runs  along  the  border  of  the  back  of  the  fingers.  At 
the  ends  of  the  latter  the  digital  nerves  divide  into  two  branches,  of 
which  one  supplies  the  tips,  the  other  the  part  beneath  the  nail. 

10.  The  Ulnar  nerve,5  from  the  lower  and  outer  trunks  of  the  bra- 
chial plexus,  is  smaller  than  the  preceding,  and  gradually  diverges  from 
it  on  the  inner  part  of  the  arm  to  the  interval  of  the  olecranon  and  in- 
ternal condyle.    In  this  position  it  may  be  compressed  against  the  latter 
through  the  skin,  giving  rise  to  the  sensation  which  has  led  the  part 
commonly  to  be  called  the  "crazy  bone." 

Piercing  the  origin  of  the  ulno  carpal  flexor,  the  ulnar  nerve  proceeds 
between  this  muscle  arid  the  deep  flexor  of  the  fingers  to  the  wrist,  where 


1  N.    circumflexus ;     n.    axillaris;    n.  *  N.  palmaris  superficialis;    n.  cuta- 
scapulo-humeralis.  neus  palmaris ;  n.  c.  p.  longus. 

2  N.  medianus.  5  N.  ulnaris ;    n.  cubitalis ;  cubito-di- 
8  N.  interosseus  internus ;   n.  i.  pro-  gital  nerve. 

fundus. 


THE   NERVOUS   SYSTEM. 


569 


it  passes  over  the  annular  ligament  close  to  the  pisiform  bone,  and 
reaches  the  palm  of  the  hand.     Its  branches  are  as  follow : — 

a.  Articular,  muscular,  and  cutaneous  branches  to  the  elbow  joint, 
ulno-carpal  and  deep  flexor  of  the  fingers,  and  the  skin  on  the  inner 
part  of  the  forearm. 

FIG.  344.  FIG.  345. 


EXTERNAL  CCTANEOCS,  MEDIAN,  ULNAR,  AND  MUSCULO-SPIRAL  NERVES.  1,  external  cutaneous  nerve ;  2,  3, 
4,  muscular  branches;  5,  anastomotic  filament  from  the  median;  6,  division  of  the  external  cutaneous 
nerve  into  branches  to  the  forearm ;  7,  musculo-spiral  nerve ;  8,  cutaneous  branch  of  the  latter ;  9,  inter- 
nal cutaneous  nerve ;  10,  its  branches  to  the  forearm ;  11,  median  and  ulnar  nerves;  12,  median  nerve; 
13-16,  muscular  branches;  17,  anterior  interosseous  nerve;  18,  superficial  palmar  branch;  19,  branch  to 
the  muscles  of  the  ball  of  the  thumb;  20-24,  digital  nerves  of  the  thumb,  index,  middle,  and  one  side  of 
the  ring  finger;  25,  ulnar  nerve;'  26,  muscular  branches;  27,  28,  cutaneous  and  dorsal  branches  ;  30,  31, 
digitals  to  the  little  and  ring  fingers;  32,  deep  palmar  branch;  33-36,  muscular  branches  from  the  latter ; 
37,  musculo-spiral  nerve;  38,  its  posterior  interosseal  division;  39,  a  muscular  branch  of  the  latter;  40, 
radial  nerve. 

b.  A  dorsal  branch,1  which  passes  beneath  the  tendon  of  the  ulno- 
carpal  flexor  to  supply  the  skin  on  the  back  of  the  hand. 


1  N.  dorsalis  manus;  cubito-dorsal  nerve. 


570  THE   NERVOUS   SYSTEM. 

c.  The  deep  palmar  branch,  which  follows  the  corresponding  blood- 
vessels, and  supplies  the  small  muscles  of  the  little  finger,  the  interosseal 
and  lumbrical  muscles. 

d.  The  Digital  nerves,  of  which  there  are  two.     One  of  these  sup- 
plies twigs  to  the  short  palmar  muscle  and  the  skin  on  the  inner  part  of 
the  hand,  and  then  runs  along  the  inner  side  of  the  little  finger.     The 
other  passes  along  the  last  metacarpal  interval,  gives  an  offset  to  the 
last  median  digital  nerve,  and  then  divides  into  two  branches,  which 
supply  the  contiguous  sides  of  the  ring  and  little  fingers. 

11.  The  Musculo-spiral  nerve,1  from  the  posterior  trunk  of  the  bra- 
chial  plexus,  is  the  largest  branch  of  the  latter.  It  winds  in  a  half 
spiral  around  the  back  of  the  humerus,  in  company  with  the  superior 
profound  artery,  between  the  triceps  extensor  and  the  bone,  and  descends 
in  the  interval  of  the  long  supinator  and  brachial  muscle  to  the  elbow, 
where  it  divides  into  the  radial  and  posterior  interosseal  nerves.  In 
its  course  through  the  arm  it  gives  off  muscular  branches  to  the  triceps 
extensor,  anconeus,  brachial,  long  supinator,  and  long  radio-carpal  ex- 
tensor muscles,  and  cutaneous  branches  to  the  skin  on  the  inner  side  of 
the  arm  and  forearm  to  the  wrist. 

The  Radial  nerve,  the  smaller  division  of  the  musculo-spiral,  runs 
along  the  outer  part  of  the  forearm,  and  passes  beneath  the  tendon  of 
the  long  supinator.  It  then  pierces  the  fascia,  and  divides  into  branches 
which  anastomose  with  the  external  cutaneous  nerve,  and  are  distributed 
to  the  skin  on  the  outer  badfpart  of  the  hand,  the  back  of  the  thumb, 
Jhe  index  and  middle  fingers. 

The  Posterior  Interosseal  nerve  passes  through  the  short  supinator 
muscle  to  the  back  of  the  forearm,  where  it  divides  into  branches  supply- 
ing the  extensor  muscles,  except  the  long  radio-carpal  extensor.  A  term- 
inal branch  descends  on  the  interosseal  membrane  to  the  back  of  the 
wrist,  which  it  supplies. 

THE  THOEACIC  NERVES. 

There  are  twelve  pairs  of  thorac'ic  nerves,2  of  which  the  first  pair 
issue  from  the  intervertebral  foramina,  between  the  upper  two  dorsal 
vertebrae,  and  the  last  pair  between  the  last  dorsal  and  first  lumbar  ver- 
tebra. The  first  pair  is  much  the  largest ;  the  others  are  nearly  of  uni- 
form size.  After  escaping  from  the  intervertebral  foramina  they  divide 
into  anterior  and  posterior  branches. 

1  N.  musculo-spiralis ;  n.  radialis ;  n.  spiralis. 

2  Dorsal  nerves  ;  nervi  thoracicis,  or  dorsales. 


THE   NERVOUS   SYSTEM.  571, 


POSTERIOR  BRANCHES  OF  THE  THORACIC  NERVES. 

The  Posterior  branches  of  the  thoracic  nerves,  like  those  of  the 
other  spinal  nerves  generally,  are  smaller  than  the  anterior  branches. 
Turning  backward  between  the  transverse  processes  of  the  vertebrae, 
they  divide  into  external  and  internal  branches. 

The  external  branches  successively  increase  in  size  from  first  to  last, 
and  appear  in  the  interval  of  the  longissimus  and  sacro-lumbar  muscles, 
"which  they  supply.  The  lower  six  of  the  series  further  give  off  cuta- 
neous branches,  which  pierce  the  inferior  serrated  and  latissimus  muscles 
to  supply  the  skin  contiguous  to  the  angle  of  the  ribs. 

The  internal  branches  of  the  upper  six  thoracic  nerves  appear  in  the 
interval  of  the  multifid  and  semi-spinal  muscles,  to  which  they  give  fila- 
ments, and  then  supply  the  skin  in  the  vicinity  of  the  spinous  processes 
of  the  vertebra.  The  corresponding  branches  of  the  lower  six  thoracic 
nerves  terminate  in  the  multifid  spinal  muscle. 

ANTERIOR  BRANCHES  OF  THE  THORACIC  NERVES. 

The  anterior  branches  of  the  thoracic  nerves  remain  distinct  from 
one  another,  or  do  not  anastomose  and  form  plexuses  as  in  the  case  of 
the  other  spinal  nerves.     Near  their  commencement  each  communicates,  — 
by  means,  of  a  pair  of  anastomotic  filaments,  with  the  contiguous  tho- 
racic ganglia  of  the  sympathetic. 

The  anterior  branch  of  the  first  thoracic  nerve,  much  larger  than 
the  others,  as  previously  indicated,  ascends  over  the  first  rib  to  form 
part  of  the  brachial  plexus.  In  its  course  it  gives  off  a  small  branch, 
the  first  intercostal  nerve,  which  runs  along  the  first  intercostal  space. 

The  anterior  branches  of  the  succeeding  thoracic  nerves  are  of 
nearly  uniform  size,  and,  with  the  exception  of  the  last  one,  pass  out- 
wardly in  the  intercostal  spaces  as  intercostal  nerves, 

The  anterior  branch  of  the  last  thoracic  nerve  is  situated  below  the 
last  rib.  After  crossing  the  quadrate  lumbar  muscle,  it  advances  between 
the  internal  oblique  and  transverse  muscles  in  the  same  manner  as  the 
intercostal  nerves.  At  its  commencement  it  frequently  sends  an  anasto- 
motic filament  to  the  first  lumbar  nerve. 

THE  INTERCOSTAL  NERVES. 

The  first  intercostal  nerve  is  a  small  branch  given  off  from  the  ante- 
rior branch  of  the  first  thoracic  nerve,  and  supplies  the  muscles  of  the 
corresponding  intercostal  space. 


572  THE   NERVOUS   SYSTEM. 

The  lower  ten  intercostal  nerves1  are  constituted  by  the  anterior 
branches  of  the  thoracic  nerves,  from  the  second  to  the  eleventh  inclusive, 
and  pass  outwardly  in  the  lower  ten  intercostal  spaces.  They  first  rest 
against  the  external  intercostal  muscle,  and  proceed  between  the  two  in- 
tercostal muscles  in  company  with  the  corresponding  blood-vessels,  below 
which  they  are  situated.  They  then  penetrate  the  internal  intercostal 
muscle,  and  continue  forward  between  it  and  the  pleura. 

The  upper  intercostal  nerves  finally  perforate  the  fore  part  of  the 
intercostal  spaces  and  the  greater  pectoral  muscle,  and  terminate  in  the 
skin  of  the  breast  as  the  anterior  cutaneous  nerves  of  the  thorax.2 

The  lower  intercostal  nerves  pass  over  the  cartilages  of  the  ribs  at 
the  inferior  margin  of  the  thorax,  and  advance  between  the  internal 
oblique  and  transverse  muscles  of  the  abdomen  to  the  straight  muscle. 
Penetrating  this,  they  finally  end  near  the  median  line  as  the  anterior 
cutaneous  nerves  of  the  abdomen.2 

In  their  course  the  intercostal  nerves  supply  the  contiguous  muscles, 
and  give  off  lateral  cutaneous  branches.3  These  perforate  the  external 
intercostal  muscles,  and  pass  between  the  fasciculi  of  the  great  serrated 
muscle  above  and  the  external  oblique  muscle  below,  and  are  distributed 
to  the  skin  on  the  side  of  the  thorax  and  abdomen. 

The  lateral  cutaneous  branch  of  the  second  intercostal  nerve  consti- 
tutes the  inter co sto-humeral  nerve,  which  extends  across  the  axillary 
space,  anastomoses  with  the  small  cutaneous  nerve,  and  is  distributed  to 
the  skin  on  the  inner  part  of  the  arm. 

THE  LUMBAR  NERVES. 

Of  the  five  pairs  of  lumbar  nerves,4  the  first  issue  from  the  interver- 
tebral  foramina,  between  the  first  and  second  lumbar  vertebra,  and  the 
last  pair  between  the  fifth  lumbar  vertebra  and  the  sacrum.  Like  the 
cervical  and  thoracic  nerves  they  divide  into  an  anterior  arid  a  posterior 
branch. 

The  posterior  branches  of  the  lumbar  nerves  decrease  in  size  from 
above  downward,  and  pass  backward  between  the  transverse  processes 
of  the  vertebrae.  Penetrating  the  interstice  of  the  longissimus  and  sacro- 
lumbar  muscles,  they  supply  them  with  branches  and  send  filaments  to  the 
contiguous  skin. 

The  anterior  branches  of  the  lumbar  nerves  successively  increase  in 
size ;  and  at  their  commencement  each  communicates  by  a  pair  of  anas- 

1  N.  intercostales :  n.  subcostales.  3  Kami  cutanei  laterales. 

2  Kami    cutanei    intern! ;     reflected          4  N.  lumbares ;  n.  abdominales. 
nerves. 


THE  NERVOUS  SYSTEM.  573 

tomotic  filaments  with  the  neighboring  lumbar  ganglia  of  the  sympa- 
thetic. They  pursue  an  oblique  course  outward  and  downward,  partly 
through  and  partly  behind  the  psoas  muscle.  In  this  position  each  nerve 
above  sends  an  offset  to  the  one  next  below,  and  by  this  mode  of  anas- 
tomosis the  upper  four  lumbar  nerves,  in  conjunction  with  a  filament 
from  the  last  thoracic  nerve,  form  the  lumbar  plexus.  The  offset  from 
the  fourth  lumbar  nerve  joining  the  fifth,  together1  form  part  of  the 
sacral  plexus. 

THE  LUMBAR  PLEXUS. 

The  Lumbar  plexus,2  formed,  as  above  mentioned,  by  the  anastomosis 
of  the  anterior  branches  of  the  upper  four  lumbar  nerves  with  a  filament 
from  the  last  thoracic  nerve,  besides  supplying  the  psoas  and  quadrate 
lumbar  muscles,  gives  off  the  following  branches  : — 

1.  Jlio-hypogastric  nerve. 

2.  Ilio-inguinal  nerve. 

3.  Genito-crural  nerve. 

4.  External  cutaneous  nerve. 

5.  Obturator  nerve. 

6.  Anterior  crural  nerve. 

1.  The  Ilio-hypogas'tric  nerve3  springs  from  the  first  lumbar  nerve, 
passes  through  the  psoas  muscle,  and  crosses  the  quadrate  lumbar  muscle 
to  the  crest  of  the  ilium.    It  then  perforates  the  transverse  muscle  of  the 
abdomen,  and  proceeds  between  it  and  the  internal  oblique  muscle  to 
the  inguinal  canal,  through  which  it  descends,  or  it  pierces  the  tendon  of 
the  external  oblique  muscle,  to  supply  the  skin  over  the  pubis. 

2.  The  Ilio-in/guinal  nerve,4  from  the  same  source  as  the  preceding, 
passes  through  the  psoas  muscle  and  across  the  iliac  muscle  to  Poupart's 
ligament.     It  then  perforates  the  transverse  muscle,  and  descends  the 
inguinal  canal  to  supply  the  skin  of  the  penis  and  scrotum,  or  the  labium 
of  the  female. 

This  and  the  ilio-hypogastric  nerve  are  of  variable  size,  and  usually  a 
diminution  of  one  is  compensated  by  an  increase  of  the  other. 

3.  The  Genito-crural  nerve5  springs  from  the  second  lumbar  nerve, 
and  pierces  the  psoas  muscle  to  descend  on  its  anterior  surface,  upon 

1  The  lumbo  sacral  cord.  4  N.  ilio-inguinalis  ;    n.  musculo-cuta- 

2  Plexus  lumbaris.  neus  inferior. 

3  N.  ilio-hypogastricus ;  n.  musculo-          5  N.  genito-cruralis  ;  n.  pudendis  ex- 
cutaneus  superior.  ternus  ;  n.  spermaticus  externus ;  n.  in- 

guinalis  externus. 


574  THE   NERVOUS   SYSTEM. 

which  it  divides  into  two  branches.  Of  these,  the  genital  branch1 
crosses  to  the  inner  side  of  the  external  iliac  artery,  and  enters  the  in- 
guinal canal,  through  which  it  proceeds  to  be  distributed  to  the  sperm- 
atic cord  and  the  coverings  of  the  testicle,  or  in  the  female  to  the  round 
ligament,  mons  veneris,  and  labium.  The  crural  branch2  descends  on  the 
outer  side  of  the  external  iliac  artery,  and  passes  beneath  Poupart's  lig- 
ament to  supply  the  skin  in  front  of  the  thigh. 

4.  The  External  cutaneous  nerve,3  derived  from  the  second  and  third 
lumbar  nerves,  crosses  the  iliac  muscle  to  the  notch  below  the  anterior 
superior  spinous  process  of  the  ilium,  and  thence  escapes  from  the  ab- 
domen.   Piercing  the  femoral  fascia  below  Poupart's  ligament,  it  divides 
into  two  branches,  of  which  one  supplies  the  skin  on  the  outer  part  of 
the  thigh,  while  the  other  supplies  the  skin  on  the  fore  part  as  low  as  the 
knee. 

5.  The  Obtura'tor  nerve,4  larger  than  the  preceding  branches  of  the 
lumbar  plexus,  is  derived  from  the  second,  third,  and  fourth  lumbar 
nerves.     Emerging  from  beneath  the  inner  border  of  the  psoas  muscle, 
it  runs  along  the  side  of  the  pelvis,  and  escapes,  in  company  with  the  ob- 
turator blood-vessels,  through  the  foramen  of  the  obturator  membrane. 
Reaching  the  thigh,  it  divides  into  two  branches,5  of  which  one  supplies 
the  great  adductor  and  external  obturator  muscles,  and  gives  filaments 
to  the  hip  joint,  while  the  other  supplies  the  long  and  short  adductor, 
the  pectineal,  and  gracilis  muscles,  and  furnishes  filaments  to  the  skin  on 
the  inner  side  of  the  thigh. 

6.  The  Crural  nerve,6  the  largest  branch  of  the  lumbar  plexus,  is 
derived  from  the  second,  third,  and  fourth  lumbar  nerves.    Passing  from 
beneath  the  psoas  muscle,  it  descends  in  the  groove  between  this  and  the 
iliac  muscle,  and  emerges  from  the  pelvis  under  Poupart's  ligament.     In 
this  position  it  is  situated  a  short  distance  to  the  outer  side  of  the  fem- 
oral  artery,  beneath   the   femoral   fascia,  and   divides   into   numerous 
branches. 

Within  the  pelvis  it  supplies  the  iliac  muscle  ;  externally  it  gives 
muscular  branches  to  the  quadriceps  extensor,  the  sartorius,  and  pecti- 
neal muscles,  besides  which  it  gives  off  the  following : — 

1  Ramus  pudendus  externus ;  n  sper-          4  N.  obturatorius ;    n.  cruralis  poste- 
maticus  externus.  rior;  n.  c.  internus. 

2  Ramus  lumbo-inguinalis.  5  Ramus  anterior  et  posterior. 

8  Nervus  cutaneus  externus  ;  n.  c.  an-  6  N.  cruralis;  n.  c.  anterior  ;  the  ante- 
terior.  rior  crural  nerve ;  n.  femoralis ;  n.  mus- 

culo-cutaneus  femoris. 


THE  NERVOUS   SYSTEM. 


575 


a.  The  Middle  cutaneous  nerve,1  which  perforates  the  sartorius  muscle 
and  femoral  fascia  to  supply  the  skin  on  the  front  of  the  thigh  as  low  as 
the  knee. 


FIG.  340. 


FIG.  347. 


Fig,  348. — CUTANEOUS  NERVES  OF  THE  FRONT  OF  THE  THIGH.  1,  external  cutaneous  nerve ;  2,  middle  cuta- 
neous nerve;  3,  4,  5,  6,  7,  internal  cutaneous  nerve  and  its  branches;  8,  cutaneous  filaments  to  the  inner 
part  of  the  thigh  ;  9,  10,  branches  of  the  long  saphenous  nerve. 

Fig.3i7. — LUMBAR  PLEXUS  AND  ITS  BRANCHES.  1,  crural  nerve;  2,  3,  branches  to  the  iliac  and  psoas 
muscles ;  4,  the  cutaneous  nerves  cut  away;  5,  6,  small  muscular  filaments  to  the  pectineal  and  adductor 
muscles ;  7,  origin  of  the  cutaneous  filaments  seen  in  the  preceding  figure  on  the  inner  part  of  the  thigh; 
8,  cutaneous  filament  descending  to  the  inner  part  of  the  knee ;  9, 10, 11,  muscular  branches  of  the  crural 
to  the  quadriceps  extensor;  12,  long  saphenous  nerve;  13,  branch  to  the  knee  ;  14,  branch  descending  the 
leg  in  company  with  the  saphenous  vein;  15,  obturator  nerve;  16, 17,  18,  19,  branches  to  the  adductor 
and  gracilis  muscles ;  20,  branch  of  the  fourth  lumbar  nerve,  with  the  fifth  lumbar  nerve  descending  to 
join  the  first  sacral  nerve,  21 ;  22,  lumbar  and  sacral  ganglia  of  the  sympathetic ;  23,  external  cutaneous 
nerve. 


N.  cutaneus  medius;  n.  perforans. 


576  THE   NERVOUS   SYSTEM. 

b.  The  Internal  cutaneous  nerve,1  which  descends  inwardly  across  the 
femoral  blood-vessels,  and  perforates  the  fascia  to  supply  the  skin  on  the 
inner  part  of  the  thigh  to  the  knee. 

c.  The  Long  Saphenous  nerve,2  which  is  the  largest  of  the  cutaneous 
branches  of  the  anterior  crural   nerve.     It  accompanies   the   femoral 
blood-vessels  until  these  are  about  passing  through  the  opening  of  the 
great  adductor  muscle,  when  it  leaves  them,  and  descends  under  the 
sartorius  muscle  to  the  knee.    It  then  pierces  the  fascia  between  the  ten- 
dons of  the  sartorius  and  gracilis  muscles,  and  accompanies  the  long 
saphenous  vein  down  the  inner  side  of  the  leg  to  the  foot.     Above  the 
knee  it  gives  off  a  considerable  branch,  which  perforates  the  sartorius 
muscle  and  the  fascia,  and  is  distributed  to  the  skin  over  the  knee.     In 
the  remainder  of  its  course  it  is  expended  in  branches  to  the  skin  on  the 
inner  side  of  the  leg  and  foot. 

THE  SACRAL  AND  COCCYGEAL  NERVES. 

There  are  five  pairs  of  sacral,3  and  one  pair  of  coccyge'al  nerves,4 
which  successively  diminish  in  size ;  and  they  differ  from  other  spinal 
nerves  by  undergoing  division  into  anterior  and  posterior  branches 
within  the  vertebral  canal. 

The  posterior  branches  of  the  upper  four  sacral  nerves  emerge  at 
the  corresponding  sacral  foramina ;  the  posterior  branches  of  the  fifth 
sacral  and  the  coccygeal  nerve  from  the  end  of  the  vertebral  canal. 
They  anastomose  with  one  another,  forming  a  series  of  loops,  and  give 
off  filaments  which  supply  the  commencement  of  the  dorsal  extensor  and 
multifid-spinal  muscle,  and  the  contiguous  skin. 

The  anterior  branches  of  the  upper  four  sacral  nerves  emerge  at  the 
corresponding  sacral  foramina,  and,  in  conjunction  with  the  fifth,  and 
part  of  the  fourth  lumbar  nerve,  form  the  sacral  plexus. 

The  anterior  branch  of  the  fifth  sacral  nerve  is  small,  and  emerges 
from  the  end  of  the  vertebral  canal.  It  divides  into  two  branches,  of 
which  one  joins  with  a  filament  of  the  fourth  sacral  nerve  to  end  in  the 
hypogastric  plexus  of  the  sympathetic,  and  the  other  joins  the  coccygeal 
nerve. 

The  anterior  branch,  of  the  coccygeal  nerve,  smaller  than  the  pre- 
ceding, also  emerges  at  the  end  of  the  vertebral  canal.  Being  joined 
by  a  branch  of  the  last  sacral  nerve,  it  perforates  the  coccygeal  muscle 
and  the  great  sacro-sciatic  ligament,  to  terminate  in  the  contiguous  skin 
of  the  buttock. 

1  N.  cutaneus  internus ;  n.  saphenus  minor.  3  N.  sacrales. 

2  N.  saphenus  longus;  n.  s.  major.  4  N.  coccygei. 


THE   NERVOUS   SYSTEM.  577 


THE  SACRAL  PLEXUS. 

The  Sacral  plexus,1  as  previously  mentioned,  is  formed  by  the  con- 
junction of  the  anterior  branches  of  the  upper  four  sacral  nerves  with 
the  anterior  branch  of  the  fifth  and  part  of  that  of  the  fourth  lumbar 
nerves.  These  converge  from  their  respective  foramina  into  a  broad, 
flat  cord,  which  passes  from  the  cavity  of  the  pelvis  through  the  great 
sacro-sciatic  foramen,  and  mainly  ends  in  the  great  sciatic  nerve. 

The  sacral  plexus  is  triangular,  rests  against  the  pyriform  muscle,  and 
is  separated  from  the  internal  iliac  blood-vessels  and  the  neighboring 
viscera  by  the  pelvic  fascia.  Its  upper  divisions,  formed  by  the  lowest 
lumbar  and  upper  sacral  nerves,  are  of  large  and  nearly  uniform  size. 
The  division  formed  by  the  third  sacral  nerve  is  considerably  smaller 
than  those  above,  and  that  formed  by  the  fourth  sacral  nerve  is  less  than 
half  the  size  of  the  preceding. 

Besides  giving  off  small  branches,  chiefly  from  the  lower  part  of  the 
plexus,  to  the  hypogastric  plexus  of  the  sympathetic,  the  pyriform,  in- 
ternal obturator,  elevator  and  sphincter  anal,  geminous,  and  quadrate 
femoral  muscles,  it  terminates  in  the  following  branches  : — 

1.  Superior  gluteal  nerve. 

2.  Pudic  nerve. 

3.  Small  sciatic  nerve. 

4.  Great  sciatic  nerve. 

1.  The  Superior  Gluteal  nerve2  is  derived  from  the  upper  part  of  the 
sacral  plexus,  and  passes  from  the  pelvis  in  company  with  the  gluteal 
blood-vessels  at  the  upper  part  of  the  great  sciatic  foramen.     Dividing 
into  two  branches,  these  advance  between  the  middle  and  small  gluteal 
muscles,  to  which,  and  the  tensor  of  the  femoral  fascia,  they  are  dis- 
tributed. 

2.  The  Pudic  nerve3  leaves  the  lower  part  of  the  sacral  plexus,  and 
passes  from  the  pelvis  through  the  great  sciatic  foramen  below  the  pyri- 
form muscle.     Turning  behind  the  spine  of  the  ischium,  it  re-enters  the 
pelvis  through  the  small  sciatic  foramen,  and  accompanies  the  internal 
pudic  artery  along  the  outer  part  of  the  ischio-rectal  fossa.    Its  branches 
are  as  follow  : — 

a.  The  inferior  haemorrhoidal  nerve,4  which  is  given  off  near  the 

1  Plexus   sacralis;    p.  ischiaticus ;    p.  3N.  pudendus;  n.  spermaticus  com- 
femoralis  inferior.                                              inunis. 

2  Nervus  glutoeus  superior.  *N.  hsemorrhoidalis  imus. 

37 


578  THE  NERVOUS   SYSTEM. 

commencement  of  the  pudic,  or  sometimes  directly  from  the  sacral 
plexus.  Accompanying  the  trunk  of  the  pudic  through  the  small  sci- 
atic foramen,  it  descends  to  the  extremity  of  the  rectum,  and  terminates 
in  the  sphincter  of  the  anus  and  the  adjacent  integument. 

b.  The  perineal  nerve.1     This  divides  into   superficial  branches, 
which  are  distributed  to  the  skin  of  the  perineum ;  and  deep  branches, 
which  supply  the  muscles  of  the  perineum  and  penis,  and  the  posterior 
part  of  the  scrotum.     In  the  female,  in  correspondence  with  the  latter 
parts,  it  supplies  the  muscles  of  the  vagina  and  clitoris,  the  vestibule, 
the  nymphae,  and  the  labia. 

c.  The  dorsal  nerve  of  the  penis,2  or  of  the  clitoris.3    This  accom- 
panies  the  corresponding  artery  between   the  cavernous  and  spongy 
bodies  to  the  back  of  the  organ,  along  which  it  proceeds  to  the  glans. 
It  supplies  the  cavernous  and  spongy  bodies,  the  glans  and  prepuce,  the 
skin  of  the  penis,  or  the  upper  part  of  the  nymphse. 

3.  The  Small  Sciat'ic  nerve4  is  derived  from  the  lower  part  of  the 
sacral  plexus,  through  the  union  of  two  or  three  narrow  offsets.     Pass- 
ing from  the  cavity  of  the  pelvis  through  the  great  sciatic  foramen,  be- 
low the  pyriform  muscle,  it  descends  upon  the  back  of  the  thigh  and  leg. 

At  the  upper  part  of  its  course  it  is  under  the  great  gluteal  muscle, 
and  gives  off  the  inferior  gluteal  and  pudendal  nerves.  It  then  proceeds 
downward  beneath  the  femoral  fascia,  and  is  resolved  into  many  small 
cutaneous  branches,  which  pierce  the  latter  and  supply  the  contiguous 
skin  of  the  thigh  and  leg. 

The  inferior  gluteal  nerves,5  usually  two  in  number,  come  from  the 
commencement  of  the  small  ischiatic  nerve  or  directly  from  the  ^sacral 
plexus  close  to  it,  and  are  distributed  to  the  great  gluteal  muscle. 

The  pudendal  nerve,6  a  large,  cutaneous  branch  of  the  small  sciatic, 
curves  forward  below  the  tuberosity  of  the  ischium,  and  is  distributed  to 
the  scrotum,  or  the  labia. 

4.  The  Great  Sciat'ic  nerve7  appears  as  a  prolongation  of  the  sacral 
plexus,  and  is  the  largest  nerve  of  the  body.     It  escapes  from  the  pelvis 


1  N.  pudendus  inferior ;    n.  spermati-  *  N.  glutaeus  inferior  et   n.  cutaneus 
cus  inferior ;  n.  ovaricus  inferior ;  n.  o.  posterior ;  n.  ischiadicus  minor, 
internus.  5  N.  glutaei  inferiores. 

2  N.  pudendus  superior;  n.  spermati-  6  N.  cutaneus   femoris   posterior;    n. 
cus  superior;  n.  ovaricus  superior;  n.  o.  pudendalis longus  inferior;  inferior  pu- 
externus  ;  n.  dorsalis  penis.  dendal  nerve. 

3  N.  clitoridis.  7  N.  ischiadicus   major;    n.   ischiadi- 

cus ;  great  femoro-popliteal  nerve. 


THE   NERVOUS   SYSTEM.  579 

through  the  great  sciatic  foramen,  below  the  pyriform  muscle,  descends 
through  the  middle  of  the  interval  between  the  tuberosity  of  the  ischium 
and  the  great  trochanter,  and  continues  along  the  back  of  the  thigh  to 
its  lower  part,  where  it  divides  into  the  external  and  internal  popliteal 
nerve.  The  division  of  the  sciatic  nerve  may  occur  at  any  point  be- 
tween the  ordinary  one  just  stated  and  its  commencement  in  the  sacral 
plexus. 

In  its  course  down  the  thigh  the  great  sciatic  nerve  gives  articular 
filaments  to  the  hip  joint,  and  muscular  branches  to  the  flexors  and 
great  adductor. 

The  External  Poplite'al  nerve1  is  the  smaller  terminal  division  of  the 
great  sciatic.  Descending  obliquely  along  the  outer  part  of  the  popli- 
teal space  to  the  fibula  below  its  head,  it  passes  between  that  bone  and 
the  long  peroneal  muscle,  and  divides  into  the  anterior  tibial  and  mus- 
culo-cutaneous  nerves.  In  its  course  it  gives  off  several  articular 
branches  to  the  knee  joint,  a  couple  of  cutaneous  branches2  to  the  skin 
on  the  outer  part  of  the  leg,  and  the  peroneal  communicating  branch,3 
which  descends  the  back  of  the  leg  to  join  the  short  saphenous  nerve. 

The  anterior  tibial  nerve4  passes  beneath  the  long  extensor  of  the 
toes,  and  reaches  the  fore  part  of  the  interosseal  membrane,  to  accom- 
pany the  anterior  tibial  vessels  down  the  leg.  In  its  course  it  furnishes 
filaments  to  the  contiguous  muscles,  and  in  front  of  the  ankle  joint  divides 
into  two  branches,  of  which  one  supplies  the  short  extensor  of  the  toes, 
and  the  other  follows  the  dorsal  pedal  artery,  and  supplies  the  inner  part 
of  the  foot. 

The  musculo-cutaneous  nerve5  descends  between  the  peroneal  muscles 
and  the  long  extensor  of  the  toes,  giving  them  branches,  and  reaches  the 
lower  third  of  the  front  of  the  leg,  where  it  perforates  the  fascia  and  be- 
comes subcutaneous.  Continuing  its  descent,  it  divides  into  two  branches, 
which  supply  the  skin  on  the  back  of  the  foot  and  toes. 

The  Internal  Poplite'al  nerve,6  the  larger  of  the  terminal  divisions  of 
the  great  sciatic  nerve,  is  continued  in  the  direction  of  the  parent  trunk. 
It  occupies  the  middle  of  the  popliteal  space,  more  superficially  than  the 
blood-vessels,  and  at  the  lower  margin  of  the  popliteal  muscle  assumes 
the  name  of  the  posterior  tibial  nerve.  It  gives  off  two  or  three  ar- 

1  N.  popliteus  externus;  n.  peroneus;  4  N.  tibialis  anterior;  n.  peroneus  pro- 
n.  fibularis  ;  n.  ischiadicus  minor.  fundus ;  n.  interosseus. 

2  Peroneo-cutaneous  nerves.  5  N.  musculo-cutaneus  ;   m.  peroneus 

3  N.  communicans  fibularis.  superficialis. 

6  N.  popliteus  internus ;  n.  tibialis. 


580 


THE  NERVOUS   SYSTEM. 


ticular  branches  to  the  knee  joint,  and  muscular  branches  to  the  gas- 
trocnemius,  soleus,  plantar,  and  popliteal  muscles.  It  also  gives  off  the 
short  saphenous  nerve,1  which  descends  between  the  gastrocnemius 


FIG.  348. 


FIG.  349. 


Fig.  348.  EXTERNAL  POPLITEAL  NERVE  AND  ITS  BRANCHES.  1,  external  popliteal  nerve ;  2,  cutaneous 
branch  to  the  outer  part  of  the  leg;  3,  peroneal  communicating  branch  anastomosing  with  the  short  saphe- 
nous nerve  4,  5;  6,  7,  8,  terminal  branches  of  the  latter  to  the  outer  part  of  the  foot;  9,  musculo-cutane- 
ous  nerve;  10, 11, 1'2,  terminal  branches  to  the  back  of  the  foot;  13,  anterior  tibial  nerve;  U,  terminal 
branch  of  the  latter  anastomosing  with  branches  of  the  musculo-cutaneous  nerve;  15,  muscular  branches. 

Fig.  349.  POPLITEAL  NERVES.  1,  internal  popliteal  nerve;  2,  3,  4,  muscular  branches;  5,  short  saphe- 
nous nerve;  6,  external  popliteal  nerve ;  7,  cutaneous  branch ;  8,  peroneal  communicating  branch  joining 
the  short  saphenous  nerve ;  9,  common  trunk  of  the  peroueal  communicating  and  saphenous  nerves  to  the 
outer  part  of  the  foot ;  10,  branch  to  the  heel ;  11,  cutaneous  branch  from  the  posterior  tibial  nerve ;  12, 
13,  branches  of  the  long  saphenous  nerve. 


1  N.  saphenus  externus;  n.  s.  brevis;  n.  communicans  tibialis;  ramus  commu- 
nicans  nervi  tibici;  n.  cutaneus  longus  cruris  et  pedis. 


THE  NERVOUS  SYSTEM.  581 

muscle  and  the  fascia,  and  about  the  middle  of  the  leg  perforates  the 
latter  and  becomes  subcutaneous.  It  then  usually  receives  the  peroneal 
communicating  branch1  of  the  external  popliteal  nerve,  and  descends, 
in  company  with  the  short  saphenous  vein,  to  the  outer  side  of  the  foot, 
to  which  it  is  distributed. 

The  Posterior  Tibial  nerve  is  the  continuation  of  the  internal  pop- 
liteal nerve  from  the  lower  margin  of  the  popliteal  space.  It  descends 
the  back  of  the  leg,  in  company  with  the  posterior  tibial  vessels,  supply- 
ing in  its  course  muscular  branches  to  the  posterior  tibial  and  long 
flexor  muscles  of  the  toes,  and  a  cutaneous  branch  to  the  skin  of  the 
heel.  Behind  the  inner  ankle  it  divides  into  the  two  plantar  nerves. 

The  Internal  plantar  nerve2  accompanies  the  corresponding  artery 
in  the  sole  of  the  foot,  in  its  course  giving  branches  to  the  short  flexor 
of  the  toes,  the  abductor  of  the  great  toe,  and  the  skin  of  the  sole.  At 
the  back  part  of  the  metatarsus  it  divides  into  four  digital  nerves,  of 
which  one  courses  along  the  inner  side  of  the  great  toe,  while  the  other 
three  pass  forward  in  the  succeeding  three  metatarsal  intervals,  and  bi- 
furcate to  supply  the  contiguous  sides  of  the  corresponding  toes.  These 
digital  nerves  also  supply  the  short  flexor  muscle  of  the  great  toe  and 
the  contiguous  lumbrical  muscles. 

The  External  plantar  nerve,8  the  smaller  of  the  terminal  divisions 
of  the  posterior  tibial,  passes  between  the  short  digital  and  accessory 
flexors  to  the  outer  side  of  the  foot.  In  its  course  it  gives  muscular 
branches  to  the  short  and  accessory  flexors  of  the  toes,  the  muscles 
of  the  little  toe,  the  adductor  of  the  great  toe,  and  the  interosseal,  trans- 
verse, and  outer  lumbrical  muscles.  It  also  gives  cutaneous  filaments 
to  the  outer  part  of  the  sole,  and  terminates  in  two  digital  nerves, 
which  supply  the  outer  side  of  the  little  toe  and  the  contiguous  sides  of 
this  and  the  adjoining  toe. 

THE  SYMPATHETIC  SYSTEM  OF  NERVES. 

The  Sympathetic  system  of  nerves*  is  mainly  devoted  to  supply  the 
viscera  of  the  great  cavities  of  the  body,  though  the  respiratory  organs, 
the  heart,  and  the  extremities  of  the  alimentary  canal  also  receive  nerves 
from  the  cerebro-spinal  system.  The  nerves  of  the  sympathetic  system 
are  generally  much  smaller,  less  strong,  and  less  distinctly  observable 

1  N.  communicans  fibularis.  organic  nervous  system;    nervous  sys- 

2  N.  plantaris  internus.  tem  of  the  automatic  functions ;  nerves 

3  N.  plantaris  externus.  of  organic  life ;  great  intercostal  nerves; 

4  Great   sympathetic    nerves;     tri-  vertebral  nerves;  vaso-motor  nerves, 
splanchnic  nerves ;    ganglionic  nerves ; 


582  THE   NERVOUS   SYSTEM. 

than  those  of  the  cerebro-spinal  system.  Usually  they  possess  a  more 
or  less  grayish  aspect,  closely  adhere  to  contiguous  structures  by  a  pro- 
fusion of  connective  tissue,  and  are  connected  with  many  ganglia. 

Like  the  cerebro-spinal  system,  the  sympathetic  system  is  double.  It 
consists  of  a  gangliated  cord,  extending  on  each  side  of  the  body  the 
entire  length  of  the  vertebral  column,  intercommunicating  with  the 
neighboring  cerebro-spinal  nerves  by  means  of  anastomotic  filaments,1 
and  sending  off  numerous  branches,  which  form  intricate  plexuses  often 
associated  with  additional  ganglia,  and  usually  following  the  course  of 
the  blood-vessels  to  the  viscera. 

The  gangliated  cords  of  the  two  sympathetics  lie  nearly  parallel  to 
each  other  as  far  down  as  the  sacrum,  upon  which  they  gradually  con- 
verge and  conjoin  in  a  single  minute  ganglion  resting  on  the  coccyx. 
The  ganglia  of  each  cord  correspond  in  number,  and  nearly  in  position 
with  the  segments  of  the  vertebral  column,  except  in  the  neck,  where 
there  are  but  three.  These  ganglia  intercommunicate  with  the  contigu- 
ous cerebro-spinal  nerves  by  means  of  short,  narrow  cords,  composed  of 
an  interchange  of  nerve  fibres  of  the  two  systems,  which  thus  become 
closely  associated. 

Many  of  the  nerves  from  the  gangliated  cords  at  once  follow  the 
course  of  the  contiguous  blood-vessels  to  their  ultimate  destination ; 
but  the  greater  number  and  larger  ones  contribute  to  the  formation  of 
three  most  intricate  plexuses  common  to  the  two  sympathetic  nerves. 
These  symmetrical  plexuses  are  situated  in  front  of  the  vertebral  column, 
within  the  thorax,  abdomen,  and  pelvis,  and  are  successively  named  the 
cardiac,  solar,  and  hypogastric  plexuses.  With  them  are  associated 
many  ganglia,  and  they  are  resolved  into  smaller  plexuses,  which  accom- 
pany the  contiguous  blood-vessels  to  the  neighboring  organs. 

The  gangliated  cord  of  the  sympathetics,  from  the  different  positions 
it  occupies  in  its  course,  for  description  is  conveniently  divided  into  the 
cervical,  dorsal,  lumbar,  and  sacral  portions.  These,  with  the  three  great 
symmetrical  plexuses  above  indicated,  will  be  separately  considered. 

(For  the  upper  part  of  the  sympathetic  nerve  see  figures  339,  340.) 

CERVICAL  PORTION  OF  THE  SYMPATHETIC  NERVE. 

In  the  neck  the  gangliated  cord  of  the  sympathetic  nerve  rests  upon 
the  muscles  in  front  of  the  cervical  vertebrae,  behind  the  great  blood- 
vessels. It  posseses  three  ganglia,  which  are  called,  from  their  relative 
position,  superior,  middle,  and  inferior. 

1  Kami  communicantes. 


THE  NERVOUS  SYSTEM.  583 

The  Superior  cer'vical  ganglion1  is  the  largest  of  the  cervical 
series,  and  is  usually  fusiform.  It  rests  on  the  greater  straight  muscle  in 
front  of  the  second  and  third  cervical  vertebrae  and  behind  the  internal 
carotid  artery.  It  is  connected  by  intervening  filaments  with  the  upper 
four  spinal  nerves,  the  petrosal  ganglion  of  the  glosso-pharyngeal,  the 
ganglia  of  the  pneumogastric,  and  with  the  hypoglossal  nerve.  Besides 
the  cord  of  communication  with  the  second  cervical  ganglion,  it  gives  off 
an  ascending  branch,  vascular  branches,  pharyngeal  nerves,  and  the 
superior  cardiac  nerve. 

1.  The  Ascending  branch2  of  the  superior  cervical  ganglion  appears 
as  the  continuation  of  the  sympathetic  accompanying  the  internal  carotid 
artery  through  the  carotid  canal  of  the  temporal  bone.      It  divides  into 
two  branches,  which  subdivide  and  communicate  with  one  another  around 
the  artery,  and  thus  form  the  carotid  plexus.     This  plexus,  by  means  of 
one  or  two  filaments,  joins  the  abducent  nerve ;  and,  through  the  deep  pe- 
trosal branch  of  the  pterygoid  nerve,  it  joins  the  spheno-palatine  ganglion. 
The  continuation  of  the  plexus  upon  the  same  artery  in  the  cavernous 
sinus  constitutes  the  cavernous  plexus,  and  this  communicates  through 
fine  filaments  with  the  semilunar  ganglion  of  the  trifacial  nerve,  with  the 
oculo-motor,  the  pathetic,  and  the  ophthalmic  nerves,  and  with  the  oph- 
thalmic ganglion.     From  the  carotid  and  cavernous  plexuses  fine  fila- 
ments are  given  off,  which  accompany  all  the  branches  of  the  internal 
carotid  artery. 

2.  The  Vascular  branches3  of  the  first  cervical  ganglion  apply  them- 
selves to  the  external  carotid  artery,  and  form  plexuses  upon  it  and  its 
ramifications.    By  means  of  the  plexuses  on  the  facial  and  internal  max- 
illary arteries,  the  sympathetic  nerve  is  brought  into  communication  with 
the  submaxillary  and  otic  ganglia. 

3.  The  Pharynge'al  nerves,4  of  which  there  are  two  or  three,  descend 
to  the  side  of  the  pharynx,  and,  in  conjunction  with  the  branches  derived 
from  the  glosso-pharyngeal  and  pneumogastric  nerves,  form  the  pharyn- 
geal plexus,  which   supplies  the  mucous   membrane   and  constrictor 
muscles  of  the  pharynx. 

4.  The  Superior  cardiac  nerve5  is  derived  from  the  first  cervical  gan- 
glion and  the  cord  below  it  by  two  or  three  filaments,  and  descends  the 

1  Ganglion  cervicale  superius.  4  Kami  pharyngei. 

2  Ramus  ascendens ;  cranial  branch.  5  Nervus  cardiacus  superficialis,  supe- 

3  Nervi  molles.  rior,  supremus,  or  magnus. 


584      .  THE   NERVOUS   SYSTEM. 

neck  behind  the  great  blood-vessels,  to  enter  the  thorax.  On  the  right 
side  it  passes  either  in  front  of  or  behind  the  subclavian  artery,  and  then 
along  the  innominate  artery  to  the  back  of  the  arch  of  the  aorta,  where 
it  ends  in  the  deeper  part  of  the  cardiac  plexus.  On  the  left  side,  the 
nerve  follows  the  carotid  artery  to  the  arch  of  the  aorta,  and  usually 
ends  in  the  superficial  part  of  the  cardiac  plexus.  In  its  course  down  the 
neck,  the  superior  cardiac  nerve  receives  branches  from  the  pneumogas- 
tric  nerve,  and  it  gives  filaments  to  the  inferior  thyroid  artery. 

The  Middle  cervical  ganglion1  is  small,  and  is  connected  with  the 
third  ganglion  by  several  branches.  Sometimes  it  is  indistinct,  and  appears 
to  be  associated  with  the  third  ganglion.  It  rests  against  the  inferior 
thyroid  artery,  opposite  the  fifth  cervical  vertebra,  and  is  usually  con- 
nected by  intervening  filaments  with  the  fifth  and  sixth  spinal  nerves. 
Besides  giving  branches  to  the  inferior  thyroid  artery,  following  that 
vessel  to  the  thyroid  body,  it  gives  off  the  Middle  cardiac  nerve.2  This 
descends  to  the  root  of  the  neck,  communicates  with  the  superior  and 
inferior  cardiac  and  pneumogastric  nerves,  and  ends  in  the  deeper  part 
of  the  cardiac  plexus. 

The  Inferior  cervical  ganglion,3  irregularly  crescentic  in  form,  is  situ- 
ated between  the  transverse  process  of  the  last  cervical  vertebra  and  the 
first  rib,  behind  the  vertebral  artery.  It  is  connected  with  the  first  tho- 
racic ganglion  by  several  branches,  some  of  which  pass  in  front  and  some 
behind  the  subclavian  artery.  It  communicates  by  short  cords  with 
the  seventh  and  eighth  spinal  nerves.  Besides  sending  filaments  to  con- 
tribute in  the  formation  of  the  plexus  accompanying  the  vertebral  artery, 
it  gives  off  the  Inferior  cardiac  nerve,4  which,  after  communicating  with 
the  middle  cardiac  and  inferior  laryngeal  nerves,  terminates  in  the 
deeper  part  of  the  cardiac  plexus.  It  sometimes  receives  a  contribution 
from  the  first  thoracic  ganglion ;  and  on  the  left  side  is  often  blended 
with  the  middle  cardiac  nerve. 

THE  CARDIAC  PLEXUS. 

The  Cardiac  plexus5  of  the  sympathetic  nerve  is  situated  behind  and 
beneath  the  arch  of  the  aorta,  and  is  formed  from  the  three  cardiac 
nerves  derived  from  the  cervical  ganglia,  together  with  branches  derived 
from  the  first  thoracic  ganglia  and  pneumogastric  nerves.  Beneath 

1  Ganglion  cervicale  medium ;    g.  thy-      ultimum,  thyroideum,  vertebrale,  stella- 
roideum.  turn,  or  cardiacum  tertium. 

2  Nervus  cardiacus  medius,  profundus,  4  Nervus  cardiacus  inferius. 

or  magnus.  5  Superficial  and  deep  cardiac  plexus; 

3  Ganglion  cervicale  infinum,  inferius,       plexus  cardiacus  guperficialis  et  magnus 

profundus. 


THE   NERVOUS  SYSTEM.  585 

the  arch  of  the  aorta,  above  the  point  of  division  of  the  pulmonary 
artery,  the  plexus  contains  one  or  two  small  ganglia,1  called  cardiac  from 
their  position.  From  the  cardiac  plexus  prolongations  accompany  the 
coronary  arteries,  and  are  named  the  coronary  plexuses. 

THORACIC  PORTION  OF  THE  SYMPATHETIC  NERYE. 

In  the  thorax  the  gangliated  cord  of  the  sympathetic  nerve  is  situated 
at  the  side  of  the  vertebral  column,  along  the  line  of  the  heads  of  the 
ribs,  and  is  covered  by  the  pleura.  The  ganglia,  twelve  in  number,  rest 
on  the  heads  of  the  ribs.  They  are  irregularly  triangular,  and  are  gen- 
erally associated,  each  by  means  of  two  narrow  cords,  with  the  nearest 
intercostal  nerve.  The  first  thoracic  ganglion  joins  the  last  cervical 
ganglion,  as  previously  stated ;  the  last  one  communicates  through  the 
diaphragm  with  the  first  lumbar  ganglion. 

The  upper  six  thoracic  ganglia  give  off  small  branches  to  the  aorta, 
the  intercostal  blood-vessels,  and  the  oesophageal  and  pulmonary  plexuses 
of  the  pneumogastric  nerve.  The  lower  six  ganglia,  besides  furnishing 
filaments  to  the  aorta,  give  off  branches  which  conjoin  to  form  the  three 
splanchnic  nerves. 

The  Great  Splanch'nic  nerve2  derives  its  roots  from  the  sixth  to  the 
tenth  thoracic  ganglia.  Descending  obliquely  over  the  bodies  of  the 
dorsal  vertebrae,  it  perforates  the  cms  of  the  diaphragm,  and  terminates 
in  the  semilunar  ganglion. 

The  Small  Splanchnic  nerve3  derives  its  roots  from  the  tenth  and 
eleventh  thoracic  ganglia,  and  accompanies  the  preceding  nerve  through 
the  diaphragm,  and  terminates  in  the  solar  plexus. 

The  Third  Splanchnic  nerve4  comes  from  the  twelfth  thoracic  gan- 
glion, and,  after  piercing  the  diaphragm,  ends  in  the  renal  plexus.  Its 
place  is  sometimes  supplied  by  a  branch  from  the  preceding  nerve. 

THE  SOLAR  PLEXUS. 

The  Solar  plexus5  is  the  most  extensive  of  those  of  the  sympathetic 
system,  and  is  so  named  from  the  multitude  of  filaments  radiating  there- 

1  Ganglion  cardiacum  Wrisbergii ;  g.  c.  3  N.  splanchnicus  medius,  minor,  or 
magnum ;  g.  c.  inferius  ;    g.  thoracicuin       inferior. 

rami  cardiaci  superioris.  *  N.  splanchnicus  inferior,  inferius,  or 

2  N.  splanchnicus   maximus,    major,       minimus;  least  splanchnic  nerve, 
superior,  or  primus.  5  Plexus  Solaris ;  p.  epigastricus ;  cen- 
trum commune. 


586  THE   NERVOUS   SYSTEM. 

from.  It  is  situated  behind  the  stomach,  in  front  of  the  aorta  and  the 
crura  of  the  diaphragm,  surrounding  the  cceliac  and  commencement  of 
the  superior  mesenteric  artery,  and  extending  between  the  supra-renal 
bodies.  It  is  composed  of  a  highly  intricate  intertexture  of  nerves 
associated  with  ganglia  ;  and  on  both  sides  it  receives  the  great  and 
small  splanchnic  nerves,  together  with  some  filaments  from  the  pneumo- 
gastric  nerves.  Among  the  ganglia,  which  are  variable  in  size  and  num- 
ber, generally  there  is  one  on  each  side  of  the  plexus  conspicuous  for  its 
size  and  shape,  named  the  semilunar  ganglion,1  This  is  situated  at  the 
side  of  the  coeliac  and  superior  mesenteric  arteries,  and  receives  the 
great  splanchnic  nerve. 

From  the  solar  plexus  emanate  a  multitude  of  nerves,  which  pursue 
the  course  of  the  neighboring  arteries,  form  plexuses  upon  them,  and 
partake  in  their  ultimate  distribution  to  the  viscera.  These  secondary 
plexuses  are  as  follow  : — 

The  Phrenic  plexus,2  accompanying  the  corresponding  artery  on  each 
side  to  the  diaphragm. 

The  Coronary,  Hepatic,  and  Splenic  plexuses,  pursuing  the  like- 
named  arteries  to  the  stomach,  liver,  pancreas,  and  spleen. 

The  Supra-renal  plexus  to  the  supra-renal  body.  This  is  large  in 
comparison  with  the  organ  it  supplies,  and  usually  contains  a  ganglion.3 

The  Renal  plexus,  which  accompanies  the  renal  artery  to  the  kidney. 
It  receives  the  third  splanchnic  nerve,  and  contains  several  small  gan- 
glia. An  offset,  pursuing  the  course  of  the  spermatic  artery,  constitutes 
the  spermatic  plexus. 

The  Superior  mesenteric  plexus,  following  the  corresponding  artery 
and  its  branches  to  the  intestines.  With  its  commencement  several  small 
ganglia  are  associated. 

The  Aortic  plexus,  which  is  the  continuation  of  the  solar  plexus,  de- 
scending upon  the  aorta.  It  is  intimately  associated  with  the  renal 
plexus  on  each  side,  receives  branches  from  the  lumbar  ganglia,  and 
terminates  below  in  the  hypogastric  plexus.  From  it  is  derived  the 
Inferior  mesenteric  plexus,  which  follows  the  corresponding  artery  to 
the  large  intestine. 

1  Ganglion  semilunare ;   g.  magnum ;   g.  medium ;   g.  splanchnicum ;    g.  solare ; 
g.  transversale ;  g.  abdominale  maximum ;    cerebrum  abdominale ;   centrum  nerv- 
osum. 

2  Diaphragmatic  plexus.  8  Ganglion  splanchnico-supra-renale. 


THE   NERVOUS   SYSTEM.  587 


LUMBAR  AND  SACRAL   PORTIONS  OF  THE   SYMPATHETIC 

NERVES. 

The  gangliated  cord  of  the  sympathetic  nerve  in  the  lumbar  region, 
continued  from  that  in  the  thorax,  rests  at  the  side  of  the  lumbar  verte- 
bras along  the  front  edge  of  origin  of  the  psoas  muscle.  Its  four  or  five 
ganglia  are  oblong,  oval,  and  small,  and  are  situated  at  the  sides  of  the 
vertebrae.  Each  is  connected  by  a  pair  of  communicating  filaments  with 
the  nearest  lumbar  nerve,  and  gives  off  branches  to  the  neighboring 
aortic  plexus  and  the  hypogastric  plexus. 

The  sacral  portion  of  the  gangliated  cord  lies  to  the  inner  side  of  the 
anterior  sacral  foramina,  and  terminates  in  front  of  the  coccyx  in  a 
small  ganglion  common  to  the  two  sympathetic  nerves.  Besides  the 
latter,  it  usually  possesses  four  ganglia,  which  successively  decrease  in 
size.  The  sacral  and  coccygeal  ganglia  are  each  connected  with  the  con- 
tiguous spinal  nerves  by  a  pair  of  communicating  filaments,  and  they 
give  off  branches  to  the  hypogastric  plexus. 

THE  HYPOGASTRIC  PLEXUS. 

The  Hypogas'tric  plexus,1  more  intricate  than  the  preceding  great 
plexuses  of  the  sympathetic,  is  situated  between  the  common  iliac  blood- 
vessels, and  extends2  downward  on  each  side  of  the  rectum.  It  is  formed 
from  the  termination  of  the  aortic  plexus  in  conjunction  with  branches 
from  the  lower  lumbar  ganglia,  the  sacral  ganglia,  the  lower  two  or  three 
sacral  nerves,  and  the  inferior  mesenteric  plexus.  It  is  mingled  with 
much  loose  connective  tissue,  contains  a  number  of  minute  inconspicuous 
ganglia,  and  gives  off  the  following  secondary  plexuses  : — 

The  Vesico-prostatric  plexus,3  which  extends  to  the  sides  of  the 
bladder,  the  prostate  gland,  and  the  seminal  vesicles. 

The  Vesico-vag'inal  plexus,4  which  represents  the  preceding  in  the 
female,  and  extends  to  the  sides  of  the  vagina  and  bladder. 

The  Uterine  plexus,5  which  extends  between  the  layers  of  the  broad 
ligament  to  the  uterus. 

1  Plexus hypogastricus ;  p.  h.  superior,       lateralis   inferior;    p.   ganglionus   infe- 
communis,  uterinus,  inedius,  or  impar ;       rior ;  pelvic  plexus. 

inferior  aortic  plexus ;  plexus  divisionis  3  Plexus  vesicalis  et  prostaticus,   et 

aortas.  vesiculae  seminalis. 

2  The  extensions  on  each  side  down-  *  Plexus  vesicalis  et  vaginalis. 
ward  are  the  inferior  hypogastric  plex-  5  Plexus  uterina. 

uses;    p.  hypogastricus   inferior;   p.  h. 


CHAPTER  XII. 

THE   ORGANS   OF   SPECIAL   SENSE. 

THE'NOSE. 

THE  Nose1  is  the  special  organ  of  the  sense  of  smell,  though  it  par- 
ticipates in  other  functions,  as  those  of  respiration,  and  the  voice.  For 
convenience  of  description  the  term  is  restricted  to  the  pyramidal  emi- 
nence of  the  face,  extending  from  the  forehead  to  the  upper  lip,  while 
the  other  portions  of  the  organ  are  separately  considered  as  the  nasal 
cavities. 

THE    NOSE. 

The  nose2  varies  in  its  exact  shape  and  size  in  different  races,  sexes, 
and  individuals,  and  forms  one  of  the  most  expressive  features  of  the  face. 
Its  upper  part,  firm  and  immovable,  has  for  its  basis  the  nasal  bones 
and  the  nasal  processes  of  the  superior  maxillary  bones ;  its  lower  part, 
quite  movable,  is  sustained  by  cartilages  and  tough  fibrous  membrane. 
Externally  the  nose  is  covered  by  the  skin,  and  is  furnished  with  muscles, 
and  internally  is  lined  by  an  extension  of  the  mucous  membrane  of  the 
nasal  cavities. 

The  upper  extremity  of  the  nose,  forming  an  indentation  below  the 
forehead,  is  its  root;3  the  convexity  between  the  eyes  is  the  bridge,  from 
which  the  back*  extends  to  the  tip5  and  the  sides,  terminated  below  by  con- 
vex prominences  named  the  wings.6  At  the  lower  part  of  the  nose  are 
the  nostrils  or  anterior  nares,7  a  pair  of  elliptical  orifices  directed  down- 
ward, and  separated  by  a  thick  ridge  named  the  column  of  the  nose.8 

The  skin  of  the  nose  is  thin  above,  and  readily  movable  on  the  parts 
beneath ;  but  is  much  thicker  below,  and  firmly,  adherent  to  the  carti- 
lages, and  other  subjacent  structures.  As  elsewhere,  generally,  it  is  fur- 
nished with  perspiratory  and  sebaceous  glands  and  hairs.  The  seba- 


1  Nasus ;  organon  olfactorium ;  emunc-  6  Lobulus;    lobe;    globulus  ;    apex; 
torium  cerebri.  point  of  the  nose. 

2  Nasus ;  rhin ;  promonitorium  faciei ;  6  Alse ;  pinnae. 

snout.  7   Nares ;     aperturse    nasi    externae ; 

3  Radix.  rhines  ;  narium  aditus. 

4  Dorsum  ;  rachis.  8  Columna  nasi. 

(588) 


THE   ORGANS   OF   SPECIAL  SENSE. 


589 


ceous  glands  are  comparatively  large  and  numerous  at  the  lower  part  of 
the  nose,  more  especially  along  the  groove  above  the  wing.  The  hairs 
for  the  most  part  are  exceedingly  minute,  except  within  the  margin  of 
the  nostrils,  where  they  are  well  developed  and  project  from  all  sides, 
and  in  some  measure  serve  the  purpose  of  a  sieve  in  preventing  the 
entrance  of  dust. 

The  muscles  of  the  nose  have  already  been  described  in  the  general 
account  of  the  muscles  of  the  face,  to  which  the  student  is  referred, 
pages  186,  188,  189.  They  are  the  nasal  pyramidal,  nasal  compressor, 
nasal  dilator,  labio-nasal  elevator,  and  the  labio-nasal  depressor  muscles. 

FIG.  350. 


PARTITION  OF  THE  NOSE.  1,  cartilage  of  the  partition ;  2,  its  junction  with  the  nasal  plate  of  the  eth- 
moid bone;  3,  its  junction  with  the  nasal  bones;  4,  margin  of  continuation  with  the  upper  lateral  carti- 
lage ;  5,  fibrous  membrane  connecting  the  cartilage  of  the  partition  with  the  lower  lateral  cartilage ;  6, 
inner  portion  of  the  left  lower  lateral  cartilage;  7,  anterior  border  of  the  vomer;  8,  an  accessory  carti- 
lage ;  9,  prolongation  of  the  cartilage  of  the  partition,  in  a  groove  between  the  vomer  and  nasal  plate  of 
the  ethmoid  bone;  10,  naso-palatine  canal  of  the  right  side  opening  into  the  anterior  palatine  foramen,  11. 

The  cartilages  of  the  nose  are  the  main  support  of  the  lower  part  of 
the  organ,  and  are  situated  in  front  of  the  anterior  nasal  orifice  of  the 
skull.  They  consist  of  a  cartilage  to  the  partition,  and  two  pairs  of 
lateral  cartilages,  besides  several  small  accessory  pieces. 

The  cartilage  of  the  partition1  of  the  nose  occupies  the  angular  in- 

1  Septum  cartilagineum;  cartilage  of  the  septum;  cartilage  septi  narium. 


590 


THE   ORGANS   OF   SPECIAL   SENSE. 


FIG.  351. 


terval  between  the  nasal  plate  of  the  ethmoid  bone  and  the  voraer.  It 
is  continued  forward  along  the  median  line  of  the  nasal  bones ;  below 
these  is  continuous  with  the  upper  lateral  cartilages,  and  inferiorly  con- 
tributes to  form  the  column  of  the  nose.  It  is  trapezoidal  in  outline, 
and  constitutes  about  one-third  of  the  partition  of  the  nose. 

The  Tipper  lateral  cartilages1  are  continuous  with  the  anterior  border 
of  the  cartilage  of  the  partition,  and  are  reflected  one  on  each  side  out- 
wardly to  be  attached  along  the  margin  of  the  nasal  bone  and  the  nasal 
process  of  the  superior  maxillary  bone.  They  are  triangular,  and  are 
connected  with  the  tip  and  wings  of  the  nose  by  tough  fibrous  membrane. 

The  lower  lateral  cartilages2  form  the  basis  of  the  tip,  and  contrib- 
ute to  the  column  and  wings  of  the  nose.  Each  consists  of  an  elongated 

plate  bent  upon  itself  so 
as  to  form  a  triangle, 
with  its  apex  directed  to 
the  tip,  and  its  open  base 
directed  backward.  The 
inner  portion  of  the  plate 
is  narrow,  extends  along 
the  column  of  the  nose, 
and  is  attached  to  that  of 
the  opposite  cartilage 
and  the  lower  border  of 
the  cartilage  of  the  par- 
tition by  loose  fibrous  tis- 
sue. The  outer  portion 
is  oval,  and  extends  out- 
ward and  backward  upon 
the  tip  and  upper  portion 
of  the  wing.  Its  upper 
border  and  posterior  ex- 
tremity are  attached  by 
tough  fibrous  membrane 
to  the  upper  lateral  car- 
tilage and  the  margin  of 
the  nasal  process  of  the 
maxillary  bone. 

Between  the  two  lower  lateral  cartilages,  which  adhere  to  each  other 


CARTILAGES  OF  THE  NOSE.  1,  upper  lateral  cartilage ;  2,  its  ante- 
rior border ;  3,  anterior  margin  of  the  cartilage  of  the  septum 
appearing  between  the  lateral  cartilages ;  4,  small  accessory  carti- 
lage ;  5,  lower  lateral  cartilage,  back  of  which  is  the  wing  of  the 
nose ;  6,  accessory  cartilages ;  7,  tip  of  the  nose  where  the  lower 
lateral  cartilages  are  bent  inwardly  along  the  column. 


1  Cartilagines  nasi  laterales ;  c.  laterales  superiores;  c.  triangulares. 

2  Cartilagines  alarum  nasi ;  c.  pinnalles ;  c.  laterales  inferiores ;  oval  cartilages. 


THE   ORGANS  OF  SPECIAL  SENSE.  591 

by  fibrous  tissue,  an  angular  cleft  is  left  at  the  tip  of  the  nose,  in  which 
the  skin  often  appears  depressed. 

The  accessory  cartilages1  consist  of  two  or  three  small  pieces2  im- 
bedded in  the  fibrous  membrane  behind  the  posterior  extremity  of  the 
outer  portion  of  the  lower  lateral  cartilages  —  occasionally  a  small  nod- 
ule above  the  latter — and  a  small  slip3  on  each  side  of  the  lower  margin 
posteriorly  of  the  cartilage  of  the  partition.  The  cartilages  of  the  nose 
are  composed  of  pure  cartilage,  and  are  enveloped  in  a  perichondrium 
continuous  with  the  periosteum  of  the  contiguous  bones  The  cartilage 
of  the  septum  forms  a  continuous  structure  with  the  upper  lateral  car- 
tilages, the  vomer,  and  the  nasal  plate  of  the  ethmoid  bone. 

The  wings  of  the  nose4  are  the  convex  prominences  bounding  the 
nostrils  externally,  and  separated  from  the  sides  above  by  a  furrow. 
They  are  composed  of  a  doubling  of  thick  skin  containing  a  mass  of 
tough  connective  tissue  mingled  with  adipose  tissue  and  muscular  fibres 
forming  part  of  the  insertion  of  the  nasal  muscles. 

The  cartilages  and  wings  of  the  nose  give  to  the  lower  part  of  the 
organ  its  flexibility,  and  while  they  ordinarily  preserve  the  open  con- 
dition of  the  nostrils,  they  permit  their  contraction  and  expansion. 

THE  NASAL  CAYITIES. 

The  Nasal  cavities5  are  two  narrow  but  extensive  and  complex 
spaces,  communicating  with  the  exterior  in  front  by  the  anterior  nares, 
and  with  the  pharynx  behind  by  the  posterior  nares.  Their  roof  is 
formed  by  the  nasal  bones,  the  cribriform  plate  of  the  ethmoid  bone,  and 
the  body  of  the  sphenoid  bone  ;  their  floor  is  formed  by  the  palate  pro- 
cesses of  the  superior  maxillary  and  palate  bones.  They  are  separated 
from  each  other  by  the  nasal  partition;6  their  outer  wall  supports  the 
turbinated  processes  and  bone,  between  which  are  the  three  meatuses  ; 
and  with  them  communicate  the  sphenoidal,  ethmoidal,  frontal,  and 
maxillary  sinuses.  The  mode  of  construction  of  the  nasal  cavities  by 
the  surrounding  bones  has  already  been  described  in  the  account  of  the 
skull,  page  92. 

The  anterior  nares  are  placed  below  the  level  of  the  floor  of  the  nose, 

1  Cartilagines   sesamoidese ;    c.  epac-          4  Alao  nasi ;  pinnae. 

tiles ;  c.  accessorii.  5  Fossae  nasales  ;  nasus  internus :  cavi 

2  C.  sesamoidese  ;  c.  quadratae.  narium ;  caverna  narium. 

3  Vomer  cartilaginous  dexter  et  sinister.  6  Nasal  septum. 


592 


THE   ORGANS   OF   SPECIAL   SENSE. 


at  the  most  advanced  position  of  the  organ,  and  are  directed  downward. 
The  posterior  nares  occupy  the  posterior  inferior  extremity  of  the  organ, 
and  are  directed  backward  and  downward.  Inspired  currents  of  air 
describe  a  semicircle  in  passing  through  the  nasal  cavities,  ascending 
from  the  nostrils  to  the  roof,  and  descending  to  the  posterior  nares. 
The  turbinated  processes  break  up  the  currents,  and  the  air  passes 
through  the  meatuses  and  into  the  various  sinuses,  so  that  all  parts 
of  the  nasal  surfaces  may  receive  odorous  particles  conveyed  into  the 

nose. 

FIG.  352. 


OUTER  WALL  OP  THE  LEFT  NASAL  CAVITY.  1,  superior  turbinated  process;  2,  superior  meatus ;  3,  inferior 
turbinated  process ;  4,  middle  meatus ;  5,  portion  of  the  turbinated  processes  of  the  ethmoid  bone,  removed 
to  exhibit  the  orifice  of  communication  6,  with  the  anterior  ethmoidal  sinuses ;  7,  communication  with 
the  frontal  sinus ;  8,  left  frontal  sinus ;  9,  part  of  the  unsymmetrical  partition  which  separates  the  frontal 
sinuses;  10,  turbinated  bone;  11,  inferior  meatus;  12,  laclirymo-nasal  duct  exposed  by  removing  a  por- 
tion of  the  bones;  13,  its  termination;  14,  edge  of  the  upper  lateral  cartilage;  15,  outer  part  of  the  left 
nostril;  17,  cut  edge  of  the  cartilage  of  the  partition;  18,  inner  portion  of  the  left  lower  lateral  cartilage; 
19,  gphenoidal  sinus;  20,  its  orifice;  21,  pharynx;  22,  orifice  of  the  Eustachian  tube. 

The  nasal  cavities  are  lined  throughout  with  a  highly  vascular  mucous 
membrane  intimately  adherent  to  the  subjacent  periosteum  and  peri- 
chondrium.  At  the  nostrils  it  gradually  merges  into  the  skin,  at  the 
posterior  nares  is  continuous  with  the  mucous  membrane  of  the  pharynx, 
and  through  the  lachrymo-nasal  duct  and  lachrymal  canals  with  the 
conjunctiva. 


THE  ORGANS   OF   SPECIAL   SENSE.  503 

The  nasal  mucous  membrane1  is  red,  but  varies  in  thickness,  vascu- 
larity,  and  special  structure  in  different  positions.  It  is  thickest  and 
most  vascular  upon  the  turbinated  processes,  but  especially  on  the  tur- 
binated  bone ;  and  at  their  inferior  borders  and  posterior  extremities 
it  forms  quite  thick  doublings,  which  much  increase  the  extent  of  the 
nasal  surface.  On  the  partition  it  is  also  moderately  thick,  but  in  other 
positions  is  thinner ;  and  in  the  sinuses  it  is  so  delicate  and  transparent 
as  to  assume  more  the  appearance  of  a  serous  membrane.  The  foram- 
ina communicating  with  the  sinuses  are  much  reduced  in  size,  from  what 
they  appear  in  the  macerated  skull,  by  the  reflection  of  the  mucous 
membrane  at  their  edges. 

Approaching  the  anterior  nares  the  mucous  membrane  is  compara- 
tively dry,  and  is  provided  with  a  squamous  epithelium.  In  other  po- 
sitions, including  the  sinuses  but  excluding  the  olfactory  region,  it  is 
provided  with  a  ciliated  columnar  epithelium,  and  is  furnished  with  mi- 
nute racemose  glands,2  which  are  most  numerous  where  the  membrane  is 
thickest.  In  the  olfac'tory  region,3  which  corresponds  with  the  convex 
surface  of  the  turbinated  processes  and  the  surface  of  the  nasal  plate 
of  the  ethmoid  bone,  the  mucous  membrane*  has  a  columnar  epithelium 
devoid  of  cilia,  and  is  furnished  with  simple  tubular  glands.5 

The  principal  arteries  which  supply  the  nasal  mucous  membrane  are 
the  spheno-palatine  branches  of  the  internal  maxillary,  but  it  also  re- 
ceives the  ethmoidal  branches  of  the  ophthalmic,  branches  from  the 
descending  palatine  and  dental  arteries  of  the  internal  maxillary,  and 
branches  from  the  superior  coronary  and  lateral  nasal  arteries  of  the 
facial.  The  veins  of  the  nasal  mucous  membrane  are  larger  and  more 
numerous  than  the  arteries,  and  form  a  plexus  between  the  membrane 
and  the  periosteum,  which  is  especially  well  developed  upon  the  turbin- 
ated processes  and  bone,  and  the  partition.  They  communicate  with 
veins  pursuing  the  course  of  the  spheno-palatine  artery,  and  by  eth- 
moidal branches  with  the  ophthalmic  vein. 

The  nerves  of  the  nasal  mucous  membrane  are  numerous,  and  are  of 
two  kinds — those  of  general,  and  those  of  special  sensibility.  The  for- 
mer are  the  nasal  branches  of  the  spheno-palatine  ganglion,  a  branch 
from  one  of  the  palatine  nerves,  and  the  internal  nasal  division  of  the 
nasal  nerve  of  the  ophthalmic,  Jbesides  filaments  from  the  superior  dental 
nerves. 


1  Schneiderian  membrane ;    pituitary  2  GlandulaB  muciparse  aggregate, 

membrane;  membrana  pituitaria:  m.  ol-  3  Regio  olfactorio. 

factoria;  m.  mucosa  nasi ;  m.  Schneide-  4  Olfactory  mucous  membrane, 

riana.  »  Bowman's  glands. 

38 


594  THE   ORGANS   OF   SPECIAL   SENSE. 

The  olfactory  nerves  are  those  of  special  sensibility.  The  branches 
of  each  pass  through  the  foramina  of  the  cribriform  plate  of  the 
ethmoid  bone  in  two  groups,  of  which  one  is  destined  to  the  inner,  the 
other  to  the  outer  wall  of  the  nasal  cavity.  At  first  the  branches  de- 
scend in  grooves  of  the  surfaces  of  the  bones  beneath  the  nasal  mucous 


NERVES  OF  THE  PARTITION  OF  THE  NOSE.  I,  olfactory  nerve;  1,  its  branches  descending  to  the  nasal  mu- 
cous membrane ;  2,  internal  nasal  branch  of  the  nasal  nerve  of  the  ophthalmic ;  3,  nasal  branches  from 
the  wpheno-palatine  ganglion.  II,  optic  nerve ;  III,  oculo-motor ;  IV,  pathetic ;  V,  trifacial ;  VI,  abdu- 
cent; VII,  facial;  VIII,  auditory ;  IX,  glosso-pharyngeal ;  X,  pneumogastric;  XI,  accessory;  XII,  hypo- 
glossal.  4,  cavernous  plexus  of  the  sympathetic;  5,  filaments  of  communication  with  the  semilunar 
ganglion  of  the  trifacial;  6,  filaments  of  communication  with  the  oculo-motor  nerve;  7,  branches  of  the 
sympathetic  following  the  internal  carotid  artery ;  8,  branch  connected  with  the  superior  cervical  gan- 
glion; 9, 10,  filaments  forming  a  plexus  upon  the  internal  carotid  artery;  11,  petrous  ganglion  of  the 
glosso-pharyngeal;  12,  jugular  ganglion  of  the  pneumogastric  nerve;  13,  14, 15,  anastomotic  filaments 
between  the  sympathetic,  the  glosso-pharyngeal,  pneumogastric,  accessory,  and  hypoglossal  nerves. 

(For  the  nerves  of  the  outer  wall  of  the  nose  see  figure  336,  page  547.) 

membrane,  and  then  penetrate  into  the  fibrous  layer  of  the  latter.  The 
inner  group  subdivide  into  flattened  tufts  of  filaments,  which  spread 
laterally  in  a  fan-like  manner,  but  appear  not  to  descend  below  the  nasal 
plate  of  the  ethmoid  bone.  The  outer  group  subdivide,  and,  through 
frequent  anastomoses,  produce  a  plexus  or  net-work  which  covers  the 
external  surface  of  the  turbinated  processes  of  the,  ethmoid  bone. 


THE  EYE. 

The  Eye,1  or  organ  of  sight,  includes  the  eyeball  and  the  surrounding 
structures,  named  its  appendages,2  which  consist  of  the  muscles  of  the 
eyeball,  the  eyebrows  and  eyelids  with  their  muscles,  and  the  lachrymal 
apparatus. 

1  Oculus;  ophtkalmus;  ops;  organum  visus.  2  Tutamina  oculi. 


THE   ORGANS   OF   SPECIAL   SENSE.  595 


.THE  EYEBROWS. 

The  Eyebrow1  is  the  arching  prominence  resting  upon  the  superciliary 
ridge  and  supra-orbital  margin,  between  the  forehead  and  upper  eyelid. 
It  is  composed  of  skin  thickly  provided  with  hairs,  some  subcutaneous 
connective  and  adipose  tissue,  a  portion  of  the  palpebral  orbicular,  and 
the  superciliary  muscle. 

The  hairs  of  the  eyebrow  are  stiff,  compressed,  and  pointed,  project 
very  obliquely  from  the  skin,  so  as  to  lie  in  contact  with  it,  and  are  gen- 
erally directed  along  the  line  of  the  arch  from  within  outwardly. 

THE  EYELIDS. 

The  Eyelids2  are  a  pair  of  horizontal  curtains  placed  in  front  of  the 
eye  or  of  the  orbit,  are  separated  by  the  palpebral  fissure,  and  are 
fringed  at  their  free  margins  by  the  eyelashes.  • 

The  upper  eyelid3  is  larger  than  the  lower  one,4  and  is  more  movable, 
in  consequence  of  its  being  provided  with  a  special  muscle,  the  pal'pe- 
bral  elevator. 

The  pal'pebral  fissure5  varies  in  length,  and  thus  mainly  gives  rise  to 
the  apparent  difference  of  size  of  the  eye  in  different  races  and  individ- 
uals. The  extremities  are  named  the  angles  of  the  eye,6  of  which  the 
external7  is  acute  and  the  internal8  is  prolonged  and  rounded.  The 
edges  of  the  eyelids9  are  straight,  so  that  when  they  are  closed  the  pal- 
pebral fissure  appears  as  a  transverse  slit  fringed  with  a  double  row  of 
eyelashes. 

Where  the  palpebral  fissure  commences  to  be  prolonged  to  form  the 
internal  angle,  the  border  of  each  eyelid  presents  a  slight  mammillary 
eminence,  named  the  lach/rymal  papilla.10  At  the  summit  of  this  is  a 
minute  aperture,  the  lach/rymal  orifice,11  which  is  the  commencement  of 
the  corresponding  lachrymal  canal. 

In  structure  the  eyelids  consist  of  skin,  the  palpebral  orbicular  muscle, 
the  palpebral  cartilages  and.glands,  and  a  portion  of  the  conjunctiva. 

1  Supercilium ;  ophrys.  7  External,  lesser,  or   temporal   can- 

2  Palpebrae  ;    opercula.  thus. 

3  Palpebra    superior;   p.  major;  epi-  8  Internal,  greater,  or  nasal  canthus ; 
coslis.  canthus  ;  epicanthus ;  angulus  ocularis  ; 

4  Palpebra  inferior ;  p.  minor ;  hypo-  fons  lacrymarum. 
coelis.  9  Margo  palpebrarum. 

s  Fissura  palpebrarum.  10  Papilla  lacrymalis  ;    tuberculum  la- 

6  Anguli ;  canthi.  crymale. 

11  Punctum  lacrymale. 


596 


THE   ORGANS   OF   SPECIAL  SENSE. 


The  skin  of  the  eyelids  is  thin,  delicate,  semitransparent,  and 
without  subcutaneous  adipose  tissue ;  and  at  the  edges  of  the  lids  it 
becomes  continuous  with  the  conjunctiva.  Subjacent  to  the  skin  is  the 
palpebral  orbicular  muscle,  which  in  this  position  is  thin  and  pale,  and 
specially  concerned  in  the  act  of  winking. 

The  Pal'pebral  cartilages,1  succeeding  the  muscle  just  indicated,  are 
two  thin  plates  of  fibro-cartilage,  which  give  form  and  firmness  to  the 
eyelids.  They  are  thickest  at  their  free  margin,  and  have  the  conjunc- 
tiva intimately  adherent  to  their  inner  surface.  By  their  orbital  margin 
they  are  continuous  with  an  extension2  of  the  periosteum  of  the  orbit 
and  face.  Their  inner  extremity  is  attached  by  a  round  fibrous  cord, 
the  internal  pal'pebral  ligament,3  with  the  inner  border  of  the  orbit ; 

FIG.  354. 


THE  LEFT  EYELID  AND  LACHRYMAL  GLAND,  TURNED  FORWARD  AND  INWARD  SO  AS  TO  SEE  THEIR  INNER  SUR- 
FACE. 1,  upper  and  lower  part  of  the  orbit ;  2,  portion  of  the  palpebral  orbicular  muscle;  3.  attachment 
of  this  muscle  to  the  inner  margin  of  the  orbit;  4,  perforation  for  the  passage  of  the  external  nasal 
nerve;  5,  offset  described  as  the  tensor  muscle  of  the  eyelids;  6, palpebral  glands;  7,  posterior,  and  8,  an- 
terior portions  of  the  lachrymal  glands;  9, 10,  ducts;  11,  orifices  opening  on  the  inner  surface  of  the 
tipper  eyelid ;  12, 13,  the  lachrymal  orifices  at  the  summits  of  the  lachrymal  papillae. 

and  their  outer  extremity  is  connected  with  the  contiguous  border  of  the 
orbit  by  a  somewhat  thickened  extension  of  the  periosteum,  named  the 
external  pal'pebral  ligament.4 

The  upper  pal'pebral  cartilage5  is  the  larger,  has  the  shape  of  the 


1  Tarsi:  tarsal  cartilages  or  fibro-car- 
tilages ;    coronas,   chelae,   crepidines,   or 
unguloe  palpebrarum. 

2  Ligamenta  tarsorum  superius  et  in- 
ferius;   superior  and  inferior  palpebral 
ligaments. 


3  Ligamentum  palpebrale,  interpalpe- 
brale,  or  angulare  internum;  tendo  pal- 
pebralis. 

4  L.   palpebrale,   interpalpebrale,    or 
angulare  externum. 

6  Tarsus  superior. 


THE   ORGANS  OF   SPECIAL   SENSE.  597 

long  half  of  an  oval,  and  is  about  five  lines  wide  at  the  middle.  Into 
its  upper  convex  border  the  broad,  thin  tendon  of  the  palpebral  elevator 
muscle  is  inserted.  The  lower  pal'pebral  cartilage1  is  a  band  about  a 
line  in  width,  and  has  its  borders  nearly  parallel. 

The  Pal'pebral  glands,2  about  twenty  to  each  eyelid,  are  situated 
between  the  palpebral  cartilages  and  the  conjunctiva,  through  which 
they  appear  as  vertical,  parallel  bodies,  of  a  yellowish  color  and  gran- 
ular aspect.  They  are  sebaceous  glands  lodged  in  grooves  of  the 
palpebral  cartilages,  with  the  depth  of  which  they  correspond  in 
length.  Each  gland  consists  of  a  series  of  pyriform  pouches  communi- 
cating with  a  median  duct  extending  the  length  of  the  gland  and  open- 
ing at  the  margins  of  the  eyelids.  They  secrete  an  oleaginous  matter,3 
which  prevents  the  overflow  of  the  tears  from  the  margins  of  the 
eyelids. 

The  Eyelashes4  are  the  stiff,  curved  hairs  projecting  from  the  borders 
of  the  eyelids  along  the  line  of  union  of  the  skin  with  the  conjunctiva. 
Those  of  the  upper  lid  are  more  numerous  and  longer,  and  have  their 
convexity  directed  downward ;  those  of  the  lower  lid  have  their  convex- 
ity directed  upward.  Associated  with  the  roots  of  the  eyelashes  are 
numerous  minute  sebaceous  glands,  distinguishable  as  yellowish  granules 
along  the  edges  of  the  eyelids. 

The  muscles  of  the  eyebrows  and  eyelids  are  the  palpebral  orbicular, 
superciliary,  and  palpebral  elevator  muscles,  which  are  described  in  the 
account  of  those  of  the  face,  page  1ST. 

THE  CONJUNCTIVA. 

The  Conjuneti'va5  is  the  mucous  membrane  which  lines  the  eyelids, 
and  is  thence  reflected  over  the  front  of  the  eyeball.  It  is  provided  with 
a  squamous  epithelium,  but  otherwise  varies  in  character  in  different 
positions. 

The  palpebral  portion6  of  the  conjunctiva  is  red  and  highly  vascular, 
and  is  closely  adherent  to  the  inner  surface  of  the  palpebral  cartilages. 

1  Tarsus  inferior.  *  Cilia;  epicaelides;  pili  palpebrarum ; 

2  Glands  of   Meibomius  ;    Meibomian       bletharides ;   winkers. 

glands ;  glandulse  Meibomianoe  ;  g  cili-  6  Conjunctival  membrane ;  membrana, 

ares;  folliculi  ciliares;  gland\ilae  seba-  or  tunica  conjunctiva;    tunica  adnata; 

cae  palpebrarum ;  g.  s.  ciliares ;  intesti-  circumcaulalis. 

nula  Meibomii ;  lacunae  palpebrarum.  6  Conjunctiva  palpebrarum. 

3  Gum  ;   eye-gum ;   lippitudo ;   lema ; 
sebum  palpebrale. 


598  THE   ORGANS   OF   SPECIAL   SENSE. 

It  is  furnished  with  minute  conical  papillae,  and  is  the  most  sensitive 
portion  of  the  membrane. 

At  the  inner  angle  of  the  eye  the  conjunctiva  covers  a  group  of  seba- 
ceous glands,  which  together  form  the  lach'rymal  car/uncle.1  This  is 
the  soft,  red  eminence  occupying  the  interval  of  the  internal. angle.  It 
is  furnished  with  minute  hairs,  and  secretes  an  oleaginous  material, 
which  bathes  the  lachrymal  papillae. 

At  the  outer  side  of  the  caruncle  the  conjunctiva  forms  a  narrow,  red 
doubling,  the  semllunar  fold,2  which  is  a  rudiment  of  the  third  eyelid, 
or  nictitating  membrane  of  lower  animals. 

From  the  eyelids  the  conjunctiva  is  reflected  over  the  front  part  of  the 
sclerotica  and  cornea  of  the  eyeball.  Along  the  line  of  reflection  at  the 
bottom  of  the  eyelids  it  contains  a  few  small  racemose  glands. 

The  sclerotic  portion3  of  the  conjunctiva  is  thin,  transparent,  devoid 
of  papillae,  and  less  vascular  than  the  palpebral  portion.  It  adheres 
loosely  to  the  sclerotica,  which,  seen  through  the  transparent  mem- 
brane, constitutes  the  white  of  the  eye,  The  few  large  vessels  ordina- 
rily observed  in  the  sclerotic  portion  of  the  conjunctiva  are  branches  of 
the  ophthalmic  artery,  which  terminate  in  a  fine  capillary  net-work  bor- 
dering the  cornea,  but  not  extending  beyond  it  in  a  state  of  health. 

The  corneal  portion4  of  the  conjunctiva  is  non-vascular,  highly  trans- 
parent, and  adheres  so  intimately  to  the  cornea  as  to  appear  to  be  a  part 
of  its  structure. 

THE  LACHRYMAL  APPARATUS. 

The  Lach/rymal  apparatus5  consists  of  the  lachrymal  gland,  the 
lachrymal  canals,  the  lachrymal  sac  and  its  continuation  the  lach- 
rymo-uasal  duct.  The  lachrymal  gland  secretes  the  tears,  which 
moisten  the  conjunctiva,  an  excess  ordinarily  finding  its  way  through  the 
lachrymal  canals  and  sac  into  the  nose.  Under  the  emotion  of  grief  the 
gland  is  excited  to  an  inordinate  flow  of  tears,  which  then  trickle  over 
the  edges  of  the  eyelids. 

The  Lach/rymal  gland6  is  situated  at  the  upper  outer  part  of  the 
orbit,  and  consists  of  two  portions,  of  which  the  posterior7  is  about  the 
size  and  form  of  an  almond  kernel ;  the  anterior8  is  thinner  and  irreg- 

1  Caruncula  lacrymalis.  5  Organa  lacrymalia. 

2  Plica,  valvula,  or  membrana  semilu-  6  Glandula  lacrymalis. 

naris;  palpebra  tertia.  7  G.  1  superior;  g.  innominata  Galeni. 

3  Conjunctiva  scleroticse.  8G.  1.  inferior  Rosenmulleri;  g.  congre- 

4  Conjunctiva  corneaa.  gatae  Monroi. 


THE   ORGANS   OF   SPECIAL   SENSE. 


599 


ularly  square.  Its  upper  surface  applied  to  the  roof  of  the  orbit  is 
convex ;  while  its  lower  surface,  accommodating  itself  to  the  eyeball,  is 
concave.  It  is  a  lobulated,  racemose  gland,  of  a  pinkish  hue,  and  is 
provided  with  a  transverse  series  of  about  half  a  dozen  ducts,1  which 
proceed  forward  to  open  at  the  outer  part  of  the  reflection  of  the  con- 
junctiva from  the  upper  eyelid  to  the  eyeball. 

The  Lach/rymal  canals,2  which  ordinarily  convey  the  tears  from  the 
front  of  the  eye,  commence  at  the  summit  of  the  lachrymal  papillae3  by 
a  minute  aperture,  named  the  lachrymal  orifice  or  point,4  The  upper 
canal  ascends  within  the  corresponding  eyelid;  the  lower  one  descends, 
and  both  then  abruptly  converge  inwardly  and  terminate  by  separate 
apertures  into  the  lachrymal  sac.  The  canals  expand  after  their  origin, 
and  are  composed  of  an  exterior  fibrous  tunic  and  a  lining  mucous 
membrane.  They  include  between  them  the  lachrymal  caruncle,  and  are 
covered  in  front  by  the  palpebral  orbicular  muscle. 

FIG.  355. 


3234 
THE   LEFT   ETE,  WITH  A  PORTION  OF  THE  EYELIDS   REMOVED,  TO  EXHIBIT    THE   LACHRYMAL    CANALS  AND  SAC. 

1,  lachrymal  canals ;  2,  commencement  of  these  at  the  summit  of  the  lachrymal  papilla? ;  3.  palpebral 
cartilages ;  4,  edges  of  the  eyelids ;  5,  lachrymal  sac  ;  G,  internal  palpebral  ligament ;  7,  its  point  of  divi- 
sion in  front  of  the  lachrymal  canals  ;  8,  branches  of  the  ligament  giving  attachment  to  the  fibres  of  the 
palpebral  orbicular  muscle. 

The  Lach/rymal  sac5  is  the  commencement  of  the  passage  which  con- 
ducts the  tears  from  the  front  of  the  eye  to  the  nose.     It  occupies  the 


1  Ductus  lacry males. 

2  Canaliculi  lacrymales ;  c  1.  superior 
et inferior;  c.  limacum  ;  canales,  or  duc- 
tus  lacrymales ;  d.  1.  laterales ;  d.  or  col- 
licise  punctorum  lacrymalium ;   cornua 
lacrymalia;  c.  limacum;  spiracula;  hir- 
qui ;  lachrymal  ducts. 


3  Papilla  lacrymalis ;  tuberculum  la- 
crymale. 

4  Punctum  lacrymale ;  spiramen  pal- 
pebrae. 

5  Saccus  lacrymalis;  sinus,  or  lacus 
lacrymalis;  utriculus   lacry marum;  in- 
fundibulum  lacrymale ;  lacrycystis. 


Tktt.J.  Birck  M.JO, 
f*rt  Carbon,  P&. 

600  THE   ORGANS   OF   SPECIAL   SENSE. 

fossa  between  the  lachrymal  and  superior  maxillary  bones,  and  is  about 
half  an  inch  in  length.  It  is  cylindrical,  with  a  rounded,  closed  summit 
projecting  a  short  distance  above  the  entrance  of  the  lachrymal  canals. 

The  Lach'rymo-nasal  duct1  is  formed  by  the  lachrymal,  superior  max- 
illary, and  turbinated  bones,  and  is  about  half  an  inch  in  length.  It  is 
lined  by  a  continuation  of  the  lachrymal  sac,  and  descends  to  terminate 
at  the  anterior  extremity  of  the  inferior  meatus  of  the  nose. 

The  lachrymal  sac  and  lachrymo-nasal  duct  together  have  a  nearly 
vertical  direction,  but  in  their  descent  incline  slightly  inward  and  back- 
ward. They  are  lined  with  mucous  membrane  intimately  adherent  to  the 
subjacent  periosteum,  and  continuous  above  with  the  mucous  membrane 
of  the  lachrymal  canals,  below  with  that  of  the  nose.  The  membrane  is 
pale  red,  is  provided  with  a  columnar,  ciliated  epithelium,  and  sometimes 
has  one  or  two  slight  transverse  folds. 

THE  EYEBALL. 

The  Eyeball2  is  situated  in  the  fore  part  of  the  orbit,  protected  in 
front  by  the  eyelids,  and  resting  behind  in  what  may  be  viewed  as  the 
excavated  base  of  a  conical  cushion  of  adipose  and  areolar  tissue.  It  is 
maintained  in  position  by  the  cushion  just  indicated,  by  the  optic  nerve 
and  eyelids,  but  mainly  by  the  muscles  which  surround  and  serve  to  move 
it  in  various  directions.  Its  shape  is  nearly  spherical,  with  a  diameter  a 
little  less  than  an  inch.  Viewed  in  profile,  it  presents  parts  of  two 
spheres,  of  which  the  posterior  and  larger  corresponds  with  the  sclerotica, 
and  the  smaller  is  formed  by  the  cornea  projecting  from  the  front  of 
the  larger  sphere. 

The  eyeballs  have  their  axes3  nearly  parallel,  but  the  diverging  optic 
nerves  join  the  balls  posteriorly  to  the  inner  side  of  their  axes,  and  are 
thus  brought  several  lines  nearer  the  internal  than  the  external  border  of 
the  cornea. 

In  composition  the  eyeball  consists  of  a  series  of  concentric  tunics  in- 
closing three  perfectly  transparent  and  colorless  media,  named  the  hu- 
mors of  the  eye,  The  tunics  in  succession  are,  firstly,  the  sclerotica 
and  the  cornea ;  secondly,  the  choroid  coat  and  the  iris ;  and  thirdly, 
the  retina.  The  humors  are  the  aqueous  humor,  the  crystalline  lens, 
and  the  vitreous  humor. 

1   Ductus  naso-lacrymalis ;    d  lacry-          2  The  eye ;  ball,  globe,  or  bulb  of  the 
mails;    d.  nasalis;    d.   n.  orbitre ;  d.  ad       eye;  bulbus  oculi. 
nasum  ;  nasal  canal  or  duct ;  lachrymal  3  Visual  axes, 

duct ;  canalis  lacrymalis ;  c.  1.  membra- 
naceus  ;  c.  orbitse  nasalis. 


THE   ORGANS   OF   SPECIAL   SENSE. 


601 


MUSCLES  OF  THE  EYEBALL. 

The  Straight  muscles1  of  the  eyeball,  of  which  there  are  four,  are 

named   from    their    rela- 

,.  ...         ,,       „  FIG.  356. 

tive  position  the  Supe- 
rior,2 Inferior,3  Exter- 
nal,4 and  Internal.5  They 
arise  tendinously  around 
the  optic  foramen,  and  di- 
verge forward  equidistant 
from  each  other,  to  be  in- 
serted by  tendons  into  the 
sclerotica  a  short  distance 
from  the  cornea. 

The  external  straight 
muscle  has  its  origin  di- 
dided  into  two  parts,  be- 
tween which  pass  the  ocu- 
lo-motor  and  abducent 
nerves  and  the  nasal 
branch  of  the  ophthalmic. 

The  superior  and  infe- 
rior   Straight    mUSCleS    Of     10,  inferior  oblique  muscle ;  11,  optic  nerve;  12,  cnt  surface  of  the 
the  tWO  eves  act  together       malar  process  of  the  superior  maxillary  bone;  13,  the  nasal  ori- 
*  '      fice.    A,  the  eyeball. 

and  draw  the  balls  upward 

or  downward.  The  external  straight  muscle  draws  the  eyeball  outward ; 
the  internal  draws  it  inward,  but  the  external  muscle  of  one  eye  acts  in 
conjunction  with  the  internal  muscle  of  the  other  eye.  The  united  action 
of  the  straight  muscles  draws  the  eyeball  toward  the  bottom  of  the 
orbit,  which  action,  in  a  measure,  is  antagonized  by  the  oblique  muscles. 

The  Superior  Oblique  muscle6  arises  tendinously  above  the  optic  fora- 


MUSCLES  OF  THE  EVE.  1.  the  pulpebral  elevator  muscle  ;  2,  the 
superior  oblique ;  ?>,  the  pulley  through  which  the  tendon  of  inser- 
tion plays ;  4.  superior  straight  muscle ;  5,  inferior  straight  muscle ; 
6,  external  straight  muscle ;  7,  8,  its  two  points  of  origin ;  9,  in- 
terval through  which  pass  the  oculo-motor  and  abducent  nerves ; 


1  Musculi  recti  oculi. 

2  Musculus  rectus  superior ;    m.  attol- 
lens   oculi ;  m.  levator  oculi ;  m.  super- 
bus;  m.  oculum  movens  tertius ;  elevator 
muscle  of  the  eyeball. 

3  M.  rectus  inferior ;  m  depressor  ocu- 
li ;   m.  deprimens  ;  m.  humilis  ;  m.  timi- 
dus ;    m.  oculum  movens  quartus ;   de- 
pressor muscle  of  the  eyeball. 

4  M.  rectus   externus ;    m.   abductor 
oculi;  m.  indignabundus ;  m.  indignato- 


rius ;  m.  iracundus  ;  m.  oculum  movens 
secundus ;  abductor  muscle  of  the  eye- 
ball. 

5  M.  rectus  internus;  m.  adductor  ocu- 
li ;  m.  adducens  oculi ;  m.  bibitorius ;  m. 
oculum  movens  primus ;  adductor  muscle 
of  the  eyeball. 

6  M.  obliquus  superior  oculi ;  m.  o. 
major  oculi;  m.  trochlearis;  m.  trochlea- 
tor;  m.  amatorius;  m.  circumductionis 
opifex  ;  m.  longissimus  oculi. 


602  THE   ORGANS  OF   SPECIAL   SENSE. 

men,  and  advances  along  the  upper  and  inner  part  of  the  orbit.  Term- 
inating in  a  round  tendon,  this  passes  through  a  fibre-cartilaginous 
ring  or  pulley,1  situated  in  a  depression  just  within  the  inner  extremity 
of  the  supra-orbital  margin.  The  tendon  then  turns  backward  and  out- 
ward beneath  the  superior  straight  muscle,  and  is  inserted  into  the  eye- 
ball, midway  between  the  latter  and  the  external  straight  muscle,  the  cor- 
nea and  the  optic  nerve.  To  facilitate  movement,  the  tendon  as  it 
passes  through  the  pulley  is  invested  with  a  synovial  bursa. 

The  Inferior  Oblique  muscle2  arises  from  the  superior  maxillary  bone 
within  the  lower  margin  of  the  orbit  and  just  external  to  the  lachrymal 
fossa.  Proceeding  outward  and  backward  below  the  inferior  straight 
muscle,  it  is  inserted  into  the  outer  part  of  the  eyeball  a  little  back  of  its 
middle. 

The  oblique  muscles  antagonize  the  straight  muscles  by  protruding 

the  eyeball,  and  they  also  rotate  it  on  its  axis  in  opposite  directions. 

• 

THE  SCLEROTICA. 

The  Sclerot'ica,  or  sclerot'ic  coat,8  forms  the  posterior  four-fifths 
of  the  exterior  wall  of  the  eyeball  It  is  a  strong,  white,  opaque, 
inextensible  membrane,  composed  of  interlacing  bundles  of  fibrous 
tissue,  and  is  adapted  to  give  form  and  solidity  to  the  eyeball.  Its 
front  part,  seen  through  the  conjunctiva,  is  commonly  called  the  white 
of  the  eye.4  It  is  thickest  posteriorly,  and  gradually  becomes  thin- 
ner anteriorly,  in  which  position  the  tendons  of  the  straight  and  ob- 
lique muscles  are  inserted.  Its  back  part  admits  the  optic  nerve 
through  a  funnel-shaped  opening ;  and  the  sheath  of  the  nerve  becomes 
continuous  with  the  sclerotica.  Into  a  circular  aperture  at  its  fore 
part  the  cornea  is  inserted,  in  the  manner  of  a  watch-crystal  in  its  frame. 
The  margin  of  the  aperture  is  beveled  inwardly,  so  as  to  inclose  the  cor- 
responding margin  of  the  cornea.  In  the  vicinity  of  the  optic  nerve 
and  near  the  cornea,  the  sclerotica  is  pierced  by  the  ciliary  blood-vessels 
and  nerves.  Its  inner  surface  is  brownish,  and  is  attached  to  the  choroid 
tunic  by  a  small  quantity  of  delicate  connective  tissue.5 

The  sclerotica  is  supplied  with  blood  from  branches  of  the  ciliary 
arteries ;  and  its  veins  join  the  choroid  and  ciliary  veins. 

1  Trochlea.  Candida,    or  innominata    oculi;    cornea 

2  M.  obliquus  inferior  oculi ;  m  o.  mi-       opaca. 

nor  oculi.  4  Album,  or  albumen  oculi ;  lonchades. 

3  Tunica  sclerotica;    t.  albuginea;  t.  5  Lamina,  or  membrana  fusca. 
dura,    durior,    crassior,    alba,    extima, 


THE   ORGANS  OF   SPECIAL   SENSE. 
FIG.  357. 


603 


VERTICAL  SECTION  ANTERO-POSTERIORLY  OF  THE  EYEBALL.  1,  optic  nerve;  2,  sclerotica;  3,  its  posterior 
thicker  portion;  4,  sheath  of  the  optic  nerve  continuous  with  the  sclerotica;  5,  the  nerve  within  the 
sheath;  6,  insertion  of  the  straight  muscles  into  the  sclerotica;  7,8,  superior  and  inferior  straight 
muscles  ;  9,  cornea;  10,  its  conjunctival  surface;  11,  membrane  of  the  aqueous  humor;  12,  13,  beveled 
edge  of  the  cornea  fitting  into  the  sclerotica;  14,  circular  sinus  of  the  iris;  15,  choroidea;  16,  the  anterior 
portion  of  the  same,  constituting  the  ciliary  body ;  17,  the  ciliary  muscle ;  18,  the  ciliary  processes ;  19, 
retina;  20,  its  origin;  21,  its  anterior  border;  22,  central  retinal  artery;  23,  vitreous  humor;  24,  25,  hya- 
loid tunic;  26,  27,  its  separation  into  two  lamina?,  which  inclose  the  crystalline  lens,  28;  29,  iris;  30, 
pupil ;  31,  posterior  chamber,  and  32,  anterior  chamber  occupied  by  the  aqueous  humor. 

THE  CORNEA. 

The  Cor'nea1  is  the  transparent  membrane  at  the  front  of  the  eyeball, 
the  exterior  wall  of  which  it  constitutes  the  most  prominent  fifth  part. 
By  a  beveled  margin  it  fits  into  the  circular  aperture  adapted  to  it  in  the 
sclerotica.  Externally  the  conjunctiva2  is  reflected  over  it ;  and  inter- 
nally it  is  lined  by  an  equally  transparent  layer  named  the  membrane  of 
the  aqueous  humor.3  Independently  of  the  two  layers  just  mentioned, 
the  cornea4  is  composed  of  a  fibrous  tissue  much  resembling  in  appear- 
ance and  chemical  constitution  that  not  unfrequently  observed  in  the 
matrix  of  cartilages.  The  fibrous  tissue  has  a  lamellar  arrangement,  so 
that  the  cornea  may  be  dissected  into  a  number  of  layers,  varying  with 
the  delicacy  of  manipulation.  At  the  conjunction  of  the  cornea  and 
sclerotica  the  two  become  intimately  associated,  and  in  this  position 
inclose  a  venous  channel,  called  the  circular  sinus  of  the  iris.5 


1  C.  pellucida,  lucida,  or  transparens ; 
membrana  cornea;  sclerotica  ceratoides; 
ceratoides ;  membrana  ceratoides ;  cera- 
tomeninx;  the  sight. 

2  Conjunctival  portion  of  the  cornea. 

3  Membrana,  tunica  propria,  vagina, 
or  capsula  humoris  aquei ;  m.  Descemeti ; 
m.  Demoursii;  m.  Duddeliana;  m  Demu- 


riana ;  proper  membrane  of  Descemet ; 
posterior  elastic  lamina  of  the  cornea ; 
capsula  aquea  cartilaginosa ;  c.  prsea- 
quosa. 

4  Cornea  propria. 

5  Canalis  Schlemmii ;  c.  Fontanae  ;  si- 
nus  venosus    Hovii ;    circulus  venosus 
orbiculi  iridis,  or  ciliaris. 


604 


THE   ORGANS   OF   SPECIAL   SENSE. 


The  cornea  in  a  healthy  condition  is  non-vascular,  but  is  pervaded 
with  a  system  of  branching  lacunae  which  resemble  those  of  the  bones, 
and  serve  to  convey  colorless  nutritive  liquid  throughout  the  membrane 
It  is  supplied  with  delicate  filaments  from  the  ciliary  nerves. 

On  the  approach  of  old  age  the  circumference  of  the  cornea  usually 
becomes  more  or  less  dull  or  opaque  by  the  deposit  of  fatty  matter  in  its 
tissue,  constituting  the  so-called  arcus  senilis.1 


FIG.  358. 


Fig.SbS. — THE  CHOROIDEA  AND  IRIS.  1,  ciliary  arteries  situated  at  the  sides  of  the  optic  nerve;  2,  the 
long  ciliary  arteries ;  3,  the  same  after  having  pierced  the  sclerotica ;  4,  5,  the  main  divisions  of  the  same 
vessels ;  6,  the  ciliary  muscle ;  7,  the  anterior  ciliary  arteries ;  8,  the  short  ciliary  arteries  to  the  choroidea; 
9,  the  iris  supplied  by  the  long  and  anterior  ciliary  arteries;  10,  the  pupil. 

Fig.  359. — VEINS  OP  THE  CHOROIDEA  AND  IRIS.  1,  sclerotica;  2,  choroidea;  3,  ciliary  muscle,  of  which  a 
portion  has  been  removed  to  exhibit  the  ciliary  processes,  4;  5.  the  iris;  6,  pupil;  7,  8,  trunks  of  the  cho- 
roid  veins;  9. 10,  vorticose  vessels ;  11,  their  conjunction  with  the  veins  of  the  ciliary  processes;  12,  anas- 
tomosis between  the  groups  of  vorticose  vessels. 


THE  CHOROIDEA. 

The  Choroi'dea,  or  choroid  coat,2  is  a  thin,  black,  and  highly  vascular 
membrane  succeeding  the  sclerotica  and  separating  it  from  the  retina.  It 
is  perforated  behind  for  the  passage  of  the  optic  nerve,  and  terminates 


1  Gerontoxon ;  macula  cornese  arcuata ;  leucoma  gerontotoxon. 

2  The  choroid;  tunica  or  membrana  choroidea;  t.  vasculosa;  t.  aciniformis;  t. 
rhagoides;  uvea. 


THE   ORGANS  OF  SPECIAL  SENSE. 


605 


in  front  in  the  ciliary  muscle  and  body.  Its  outer  surface,1  of  a  brownish- 
black  hue,  is  attached  to  the  sclerotica,  loosely  at  the  fore  part,  more 
intimately  behind,  by  delicate  connective  tissue  and  blood-vessels.  The 
inner  surface  is  smooth,  shining,  intensely  black,  and  is  simply  applied 
to  the  contiguous  surface  of  the  retina. 


FIG.  360. 


FJG.  361. 


VIEW  FROM  BEHIND  OF  THE  ANTERIOR  PART  OF  THE 

EYEBALL.  1,  sclerotica;  2,  clioroidea ;  3,  retina;  4, 
its  anterior  border;  5,  ciliary  processes;  6,  the 
crystalline  lens  placed  back  of  the  iris  and  pupil. 


THE  SAME  VIEW,  WITH  THE  CRYSTALLINE  LENS  AND 

RETINA  REMOVED.  1,  sclerotica ;  2,  choroidea;  3, 
ciliary  body ;  4,  line  at  which  the  retina  ceases;  5, 
ciliary  processes;  6,  iris;  7,  cornea  seen  through 
the  pupil. 


The  cil'iary  muscle2  is  a  whitish  zone  connecting  the  anterior  part  of 
the  choroidea  with  the  circumference  of  the  iris  and  the  conjuction  of  the 
sclerotica  and  cornea.  It  is  composed  of  pale,  unstriated  muscular 
fibres,  and  is  abundantly  supplied  with  nerves  and  blood-vessels. 

Within  the  position  of  the  ciliary  muscle  the  choroidea  constitutes  the 
so-called  ciliary  body,3  of  which  the  fore  part4  is  thrown  into  about 
sixty  convergent  folds,5  named  ciliary  processes.6  These  are  received 
into  corresponding  grooves  of  the  vitreous  humor  in  advance  of  the 
retina,  and  serve  to  retain  it  in  position.  Their  anterior  extremities7 
are  free,  suspended  behind  the  iris,  and  are  bathed  in  the  aqueous  humor 
of  the  posterior  chamber  of  the  eye. 

In  structure  the  choroidea  consists  of  a  vascular  lamina  lined  on  the 
interior  with  a  pigmentary  layer. 


^  l  Lamina  fusca :  1.  supra-choroidea ;  1. 
cellulosa ;  1.  arachnoidea  chorioideae  ;  1. 
villoso-glandulosa. 

2  Musculus  ciliaris;  ciliary  ligament; 
ligamentumciliare;  1.  sclerotico-chorioi- 
dale ;  1.  iridis  ;  annulus,  circulus,  orbi- 
culus,  or  plexus  ciliaris ;  interstitium 
ciliare,  or  iridis ;  tensori  chorioideae ; 
circulus  chorioideae ;  annulus  cellulosus; 
commissure  of  the  uvea ;  ciliary  circle, 
or  ring. 

V*A  ^V:  '  '      '•          £     & 


3  Corpus  ciliare ;  corona  ciliaris ;  orbi- 
culus  ciliaris ;  tunica  ciliaris ;  ciliary 
disk. 

*  Pars  plicata  corporis  ciliaris. 

5  Plicae  ciliares ;  ciliary  folds. 

6  Processus  ciliares ;   plicse   ciliares ; 
p.  corporis  ciliaris;  radii  ciliares;  striae 
ciliares,  ligamenta  ciliaria ;  nbrae  palli- 
dse. 

7  Processus  ciliares. 


606 


THE   ORGANS   OF   SPECIAL   SENSE. 


FIG.  362. 


13 


The  vascular  lamina1  is  composed  of  blood-vessels  mingled  with 

a  stroma  of  fusiform  and  stellate 
cells,  apparently  an  incipient  form 
of  connective  tissue.  The  arterial 
branches  of  the  vascular  lamina 
are  derived  from  the  short  ciliary 
arteries,  which  pierce  the  sclerotica 
in  the  vicinity  of  the  optic  nerve, 
and,  after  repeated  branching,  end 
in  a  fine  capillary  net- work.2  The 
veins  derived  from  the  latter  form 
an  intricate  and  remarkable  plexus 
exterior  to  it,  and  are  named,  from 
their  peculiar  whorled  arrange- 
ment, the  vorticose  vessels.3  These 
form  four  groups,4  and  converge  in 
curving  lines  to  four  equidistant 
trunks,  which  perforate  the  scle- 
rotica midway  between  the  cornea 
and  optic  nerve,  and  end  in  the 
ophthalmic  vein. 

The  ciliary  processes  are  equally 
vascular  with  other  portions  of  the 
choroidea.  The  arteries  proceed- 
ing from  the  latter  into  the  pro- 
cesses become  convoluted,  inoscu- 
late, and  finally  terminate  in  veins  which  pursue  a  reverse  course  to  join 
the  vorticose  vessels.  The  ciliary  muscle  is  supplied  by  terminal  branches 
of  the  short  ciliary  and  the  anterior  ciliary  arteries. 

The  pigmen'tary  layer5  of  the  inner  surface  of  the  choroidea  also  en- 
velops the  ciliary  processes.  It  consists  of  flattened,  regularly  hexahe- 
dral  nucleated  cells,  filled  with  brownish-black  granular  contents,  which 
give  to  the  choroidea  its  intensely  black  color.  In  albinoes  the  pig- 
mentary granular  matter  is  absent,  and  the  choroidea  presents  a  red 
color,  due  to  its  vascularity. 

In  many  of  the  lower  animals  the  inner  surface  of  the  choroidea  at  its 
back  part  exhibits  a  patch  of  metallic  color  and  brilliancy,  named  the 


SEGMENT  OF  THE  CHOROIDEA  AND  IRIS,  SEEN  ON  ITS 
INNER  SURFACE,  magnified  four  diameters.  1,  ciliary 
processes;  2,  their  free  extremities  behind  the  iris ; 
3,  4,  commencement  of  the  processes ;  5,  interven- 
ing reticular  folds ;  6,  veins  of  the  ciliary  processes ; 
7,  posterior  margin  of  the  ciliary  body  ;  8,  choroi- 
dea with  its  veins;  9,  iris;  10,  its  outer  border;  11, 
the  pupillary  border ;  12,  radiating  fibres  of  the 
iris;  13,  circular  fibres. 


1  Tunica  vasculosa  Halleri;  t.  chorioi- 
dea   propria;    external    layer;    proper 
vascular  layer. 

2  Membrana  chorio-capillaris ;  m.  Ho- 
vii ;  m.  Ruyschii ;  tunica  Ruyschiana. 


3  Vasa  vorticosa ;  venae  vorticosee  ;  v. 
tortuossB. 

*  Stellulae  vasculosse  Winslowii. 

5  Stratum  pigment! ;  pigmentum  ni- 
grum ;  membrana  Doellingeriana.  ' 


THE  ORGANS  OF  SPECIAL  SENSE. 


607 


tape'tum.1  In  this  the  black  pigmentary  matter  is  replaced  by  colorless 
granules,  which  reflect  the  rays  of  light  falling  upon  them,  and  thus  give 
rise  to  that  shining  of  the  eyes  of  animals  in  the  dark,  which  has  proved 
to  be  so  fertile  a  source  of  terror  to  the  superstitious. 

THE  IRIS. 

The  Iris2  is  a  flat  disk  with  a  central  aperture,  and  regulates  the 
amount  of  light  received  by  the  retina  from  its  being  endowed  with  the 
power  of  contracting  or  dilating.  It  is  inserted  into  the  anterior  border 
of  the  ciliary  muscle,  is  vertical  in  position,  and  is  bathed  in  the  aqueous 
humor.  The  anterior  surface  is  divided  into  two  zones,3  of  which  the 
outer  one  is  the  broader.  It  also  appears  striated  from  the  circumference 


ARTERIES  OF  THE  IRIS.    l,long  ciliary  arteries ;  2,  3,  their  principal  divisions;  4,  small  branches  to  the 
ciliary  muscle  ;  5,  6,  anterior  ciliary  arteries ;  7,  the  pupil. 

toward  the  pupil,  and  in  different  individuals  presents  various  shades  of 
gray,  blue,  or  brown  passing  into  black.  The  posterior  surface  is 
intensely  black,  arising  from  the  presence  of  a  layer  of  pigment  cells 
like  those  of  the  choroidea. 

The  central  aperture  of  the  iris,  named  the  pupil,4  is  circular,  and  in 


1  Membrana  versicolor. 

2  Tunica  coerulea ;  uvea. 

3  Annul!  irridis ;  annulus  major  et  mi- 
nor iridis ;  a.  externus  et  interims ;  a. 
ciliaris  et  pupillaris. 


4  Pupila ;  pupula ;  fenestra  nigrum  ; 
foramen  oculi ;  prunella ;  sight  of  the 
eye. 


608  THE  ORGANS  OF   SPECIAL  SENSE. 

the  living  eye  appears  as  a  black  spot. '  Under  the  influence  of  light  it 
decreases,  and  with  the  diminution  of  that  agency  it  enlarges. 

The  iris  is  a  highly  vascular  fibro-muscular  structure,  with  its  surfaces 
covered  by  an  epithelium.  The  posterior  layer1  of  the  latter  consists  of 
black  pigment  cells;  the  anterior  layer  is  composed  of  colorless  pave- 
ment cells.  The  muscular  fibres  of  the  iris  are  unstriated  ;  form  a  circu- 
lar layer2  around  the  pupil,  and  radiate3  toward  the  circumference  of  the 
iris. 

The  blood  of  the  iris  is  derived  from  the  long  and  anterior  ciliary 
arteries.  The  former  pierce  the  back  of  the  sclerotica,  one  on  each  side, 
and  advance  on  the  outer  surface  of  the  choroidea  to  the  ciliary  muscle, 
when  they  bifurcate  and  form  together  an  arterial  circle,  from  which  nu- 
merous branches  proceed  to  the  iris.  The  anterior  ciliary  arteries,  about 
half  a  dozen  in  number,  pierce  the  sclerotica  in  the  vicinity  of  the  cor- 
nea, and,  after  anastomosing  with  the  branches  of  the  long  ciliary  arteries, 
end  in  the  capillary  vessels  of  the  iris.  The  veins  of  the  latter  join 
the  circular  sinus,4  situated  at  the  conjunction  of  the  cornea,  sclerotica, 
and  ciliary  muscle  ;  and  the  veins  from  the  sinus  pursue  the  same  course 
as  the  anterior  ciliary  arteries  to  terminate  in  the  ophthalmic  vein. 

The  nerves  of  the  iris  are  numerous,  and  are  derived  from  the  ciliary 
nerves  which  enter  the  eyeball  by  piercing  the  back  part  of  the  sclerotica. 
Advancing  on  the  exterior  of  the  choroidea,  they  reach  the  ciliary 
muscle  and  there  form  a  plexus  from  which  the  iris  is  supplied. 

Prior  to  the  eighth  month  of  foatal  life  the  pupil  is  closed  by  a  delicate 
pu'pillary  membrane,5  which  appears  to  be  a  continuous  vascular  struc- 
ture with  the  iris.  At  birth  it  is  completely  obliterated. 

THE  RETINA. 

The  Ret'ina6  is  a  soft,  delicate,  nearly  transparent  and  colorless  mem- 
brane, which  extends  from  the  optic  nerve  on  the  inner  surface  of  the 
choroidea  to  the  ciliary  body,  where  it  terminates  in  a  waving  margin.7 
After  death  it  loses  much  of  its  transparency,  and  assumes  the  appear- 
ance of  ground  glass. 
v 

1  Uvea ;  pigmentum  nigrum ;  membra-  5  Membrana  pupillavis ;    in.  Wachen- 
na  pigmenti.  dorfiana ;  pupillse  velum. 

2  Sphincter  pupillae ;  occlusor  muscle  6  Tunica  retina ;  t.  reticularis  or  reti- 
of  the  pupil ;  fibrae  circulares.  formis ;  t.  nervea ;  t.  arachnoidea ;  t.  in- 

3  Dilator  pupillee ;  fibrse  radiatoe ;  f.       tima  oculi. 

longitudinales  iridis.  7   Ora  serrata  ;  margo  dentatus ;   m. 

*  Canal  of  Fontana,  or  of  Schlemm ;       undulato-dentatus. 
canalis  Fontanse  ;  c.  Schlemmii. 


THE   ORGANS   OF   SPECIAL   SENSE. 


609 


The  surfaces  of  the  retina  are  simply  in  contact  with  the  contiguous 
structures,  and  in  the  living  or  perfectly  fresh  state  are  smooth.  Shortly 
after  death  a  small  fold1  appears  on  the  inner  surface,  extending  a  little 
distance  outwardly  from  the  entrance  of  the  optic  nerve.  Upon  the 
summit  of  this  fold,  in  the  axis  of  the  eyeball,  there  is  a  yellow  spot,2 


FIG.  364. 


FIG.  365. 


THE  EYEBALL,  WITH  THE  SCLEROTICA,  CORNEA,  CHO- 
ROIDEA, AND  IRIS  REMOVED.  1,  optic  nerve;  2,3, 
retina;  4,  central  retinal  artery  entering  the  eye- 
ball through  the  optic  nerve  and  distributed  to  the 
retina ;  5,  6,  ciliary  zone,  at  which  the  ciliary  folds 
of  the  choroidea  impress  the  vitreous  humor;  7, 
space  of  the  hyaloid  tunic  at  the  circumference  of 
the  crystalline  lens,  8,  artificially  inflated,  and  as- 
suming the  form  of  a  beaded  canal. 


RETINA,  SEEN  ON  ITS  POSTERIOR  INNER  SURFACE. 
1,  sclerotica;  2,  choroidea;  3,  retina;  4,  white  spot 
indicating  the  entrance  of  the  optic  nerve ;  5,  cen- 
tral retinal  artery ;  6,  a  slight  fold  of  the  retina, 
upon  which  is  situated,  in  the  axis  of  the  eye,  the 
yellow  spot,  7 ;  8,  its  minute  ce  atral  aperture. 


with  an  apparent  central  aperture3  depending  on  a  thinning  of  the  retina. 
The  entrance  of  the  optic  nerve  is  seen  as  an  opaque,  white  spot,4  from 
the  centre  of  which  diverge  the  branches  of  the  central  retinal  artery. 
*  The  structure  of  the  retina  is  exceedingly  complex,  and  consists  of  a 
series  of  elements,  enumerated  from  without  inwardly,  as  follows  :  1,  a 
layer  composed  of  narrow,  vertical,  columnar  cells;5  2,  a  granular  layer;6 
3,  a  layer  of  nerve  cells  with  caudate  appendages;7  4,  nerve  fibres 
derived  from  the  expansion  of  the  optic  nerve  ;8  5,  a  structureless,  limit- 
ary membrane.9 

The  blood-vessels  derived  from  the  central  retinal  artery  form  a  cap- 


1  Plica  centralis  retinae  ;  p.  transversa 
retinas. 

2  Macula  lutea ;  m.  flava  centralis  re- 
tinas ;  limbus  luteus  foraminis  centralis. 

3  Foramen  centrale  Scemmerringii ;  fo- 
vea  centralis  retinae. 

4  Papilla,  or  colliculus  nervi  optici. 

5  Tunica  Jacobi ;  Jacob's  membrane; 
basillar    layer ;    stratum    bassillorum ; 
basilli  et  coni ;  rods  and  cones ;  prisma- 


ta  praeacuta  et  coni   gemini;    layer  of 
rods  and  cones. 

6  Stratum  granulosum. 

7  The  layer   of   cineritious   cerebral 
substance   of   Kolliker;    layer  of   gray 
nerve  substance ;  stratum  globulosum. 

8  Expansion  of  the  optic  nerve;  stra- 
tum fibrillosum;  s.  vasculoso-nerveum ; 
stratum  medullare. 

9  Membrana  limitans. 


39 


610 


THE   ORGANS   OF   SPECIAL   SENSE 


illary  net-work  in  the  nervous  layers  of  the  retina  j1  and  the  veins  return 
in  the  course  of  the  corresponding  arteries. 

The  retina  is  the  sensitive  membrane  of  the  eyeball  —  that  which  re- 
ceives the  impression  of  light,  the  form  and  color  of  exterior  objects. 

THE  AQUEOUS  HUMOR. 

The  A'queous  humor2  is  a  transparent,  colorless,  albuminoid  liquid, 
which  fills  the  space  between  the  cornea  and  crystalline  lens.  The 
space  it  occupies  is  divided  by  the  iris  into  two  parts,  named  the  anterior 
and  posterior  chambers  of  the  eye,3  of  which  the  former  is  the  larger. 
The  iris  is  freely  suspended  in  the  aqueous  humor,  both  of  its  surfaces 
being  bathed  in  it,  which  is  likewise  the  case  with  the  ciliary  processes. 

Lining  the  interior  of  the  cornea,  and  continuous  with  the  anterior  layer 
of  the  iris,  is  the  so-called  membrane  of  the  aqueous  humor.4  It  is  an 
elastic  membrane,  consisting  of  a  structureless  basement  layer  and  a 
pavement  epithelium.  Its  border  is  resolved  into  a  fine  net-work  of 
fibres,5  which  are  reflected  upon,  and  become  continuous  with,  the  ante- 
rior surface  of  the  iris. 


THE  CRYSTALLINE  LENS. 

The  Crystalline  lens6  succeeds  the  aqueous  humor  from  behind,  and 
is  the  most  consistent  of  the  humors  of  the  eye.     It  is  a  double  convex 

lens,  of  which  the  poste- 

FIG.  366.  rior  surface  is  the  more 

1234  5  convex,   and   is  received 

into  a  depression7  of  the 
vitreous  humor  :  while  its 
anterior  surface  is  bathed 

by    the     aqueOUS    humor. 

It  IS  retained    in  position 
^    fa       ^     ^^    Qf 

the  vitreous  humor,  which 
is  reflected  from  its  border  to  its  anterior  and  posterior  surfaces. 


THE  CRYSTALLINE  LENS.  1,  lens  of  a  foetus  of  seven  months  ;  2, 
lens  of  a  foetus  of  nine  months;  3,  lens  of  a  child  of  ten  years  of 
age^^ensofanadultviewedinprofilej^thesameseenonits 
anterior  surface. 


1  Lamina  vasculosa  retinae. 

2  Humor    aquosus  ;   h.   oviformis  ;    h. 
ovatus  ;  h.  oodes  ;  h.  hydatodes  ;   albu- 
gineous  humor. 

3  Camerse  oculi. 

4  Membrane  of  Descemet.     See  page 


5  Ligamentum  pectinatum  iridis  ;  pro- 
cessus  peripherici  ;  pillars  of  the  iris. 

6  Lens  crystallina  ;    corpus   crystalli- 
num  ;    crystalline  humor  or  body  ;  the 
crystallinus  ;    corpus  discoides  or  pha- 
coides  ;  phacus  ;  gemma  oculi. 

7  Fossa  lenticularis  ;  f.  patellaris. 


\ 


4/ 


THE   ORGANS   OF   SPECIAL   SENSE.  611 

From  foetal  life  to  the  adult  period  the  lens  gradually  diminishes  in  its 
degree  of  convexity,  and  increases  in  breadth ;  and  in  the  advance  of 
life  it  continues  to  decline  in  convexity.  It  is  perfectly  transparent  and 
colorless,  though  in  old  age  it  is  apt  to  assume  a  yellowish  hue.  Boil- 
ing water  or  alcohol  coagulate  it  and  render  it  hard  and  opaque  white. 

The  lens  is  provided  with  a  transparent  membranous  capsule,1  which 
is  structureless,  and  is  thickest  anteriorly.  The  substance2  of  the  lens  is 
composed  of  concentric  lamina,  which  increase  in  density  toward  the 
centre.  The  laminag  are  composed  of  hexahedral  fibres,  with  corrugated 
sides  closely  adapted  to  one  another.  In  fishes  this  corrugated  character 
is  much  exaggerated,  and  the  fibres  indigitate  by  serrated  processes. 

FIG.  367.  FIG.  368. 


CRYSTALLINE  LENS,  BREAKING  UP  INTO  SEGMENTS.  SEGMENT  OF  THE  CRYSTALLINE  LENS,  exhibiting 

the  concentric  arrangement  of  the  laminae. 

Not  unfrequently,  in  dissections,  the  lens  is  observed  with  a  disposi-. 
tion  to  separate  into  segments  from  its  axis,  and  this  appears  to  indicate 
the  arrangement  of  structure.  The  segments  are  composed  of  the  con-- 
centric laminae  above  described,  and  these  consist  of  the  hexahedral 
fibres,  which  pursue  a  direction  from  the  bases  of  the  segments  to  their 
summits  and  lateral  edges.  The  intervals  of  the  segments  are  oqcupied, 
with  a  mingled  amorphous  and  finely  granular  matter. 

Between  the  front  of  the  lens  and  its  capsule  there  exists  a  lawyer  Qf" 
delicate  epithelial  cells,3  which,  after  death,  become  detached  and  mingled 
with  some  liquid4  exuding  from  the  contiguous  structures. 

In  foetal  life,  a  vessel  from  the  central  retinal  artery  traverses  the 
axis  of  the  vitreous  humor,  and  is  distributed  to  the  capsule  of  the  lens; 
but  it  is  obliterated  before  birth. 

THE  YITEEOUS  HUMOE. 

The  Vit'reous  humor,5  less  consistent  than  the  crystalline  lens,  but 
more  so  than  the  aqueous  humor,  is  equally  transparent  and  colorless. 

1  Capsula  lentis ;  tunica  crystalioidea;  *  Liquor  or  aqua  Morgagni. 

t.  arachnoidea.  5  Corpus  vitreum ;  c.  hyaloideum ;  hu- 

2  Humor  crystallinus  ;  h.  glacialis.  mor  vitreus ;  h.  hyalinus ;  h.  glacialis. 

3  Globuli  lentis. 


612  THE   ORGANS   OF   SPECIAL   SENSE. 

It  occupies  all  the  space  included  within  the  expanse  of  the  retina  and  the 
ciliary  body,  and  consists  of  a  viscid  albuminoid  liquid1  contained  in  the 
meshes  of  a  delicate  membranous  structure,  named  the  hy'aloid  tunic.2 
This  is  homogeneous,  and,  besides  forming  partitions3  through  the  mass  of 
the  vitreous  humor,  affords  it  an  exterior  investment.  In  advance  of  the 
retina  the  hyaloid  tunic  is  thicker  than  elsewhere,  and  forms  the  ciliary 
zone.*  This  is  in  contact  externally  with  the  ciliary  body,  and  is  impressed 
by  its  processes,  which,  being  received  into  corresponding  grooves  of  the 
zone,  contribute  to  maintain  the  position  of  the  vitreous  humor.  In 
front,  the  tunic  separates  into  two  laminee,  which  diverge  upon  the  border 
of  the  crystalline  lens,  and  become  confluent  with  the  anterior  and  pos- 
terior surfaces  of  its  capsule.  The  angle  of  separation5  of  the  two 
laminae  is  partially  interrupted  at  short  distances,  so  that  when  inflated 
it  assumes  the  appearance  of  a  beaded  canal8  at  the  circumference  of  the 
lens. 

THE  EAR. 

The  Ear  or  organ  of  hearing  is  exceedingly  complicated  in  its  struc- 
ture, and  is  for  the  most  part  concealed  from  view  within  the  petrous 
portion  of  the  temporal  bone.  It  is  divisible  into  the  external,  middle, 
and  internal  ear. 

THE  EXTERNAL  EAR. 

The  External  ear  consists  of  the  auricle  and  the  external  auditory 
meatus. 

The  Auricle,7  or  ear  of  common  language,  joins  the  external  auditory 
meatus  between  the  articulation  of  the  lower  jaw  and  the  mastoid  proc- 
ess. It  resembles  the  expanded  mouth  of  a  trumpet  crushed  inwardly, 
and  mainly  derives  its  peculiar  form  from  a  fibre-cartilage.  The  wind- 
ing ridges  and  hollows  of  its  outer  surface  correspond  with  reverse  char- 
acters on  the  inner  surface  or  back  of  the  ear.  Its  lower  pendant 
portion,  named  the  lobe,8  is  a  pouch  of  skin  filled  with  connective 
tissue  and  fat. 

1  Vitrina  ocularis.  ciliaris  ;    membranula  coronas   ciliaris  ; 

2  Tunica  hyaloidea;  t.  vitrea;  mem-       corona  ciliaris;  orbiculus  capsulo-cilia- 
brana  arachnoidea.  ris ;  ligamentum  suspensorium  lentis. 

8  Hyaloidea  interna ;    pars  cellularis  5  Canal  of  Petit ;  canalis  Petitianus ; 

hyaloideae  ;    cellularis    corporis   vitrei ;  circulus  Petit! ;  camera  tertia  aquosa. 
tunica  arachnoidea.  6  Bullular  canal  of  Petit. 

4  Zona  ciliaris;   pars  ciliaris  hyaloi-  7  Auricula;    pavilion;     pinna;    ala; 

deae  ;  corpus  ciliare  hyaloideae  ;   zonula  otium. 
Zinni ;  zonula,  or  zone  of  Zinn ;  lamina          8  Lobulus  auriculas. 


THE   ORGANS   OF   SPECIAL   SENSE. 


613 


FIG.  369. 


The  inflected  border  of  the  auricle,  curving  from  above  the  audit- 
ory meatus  upward,  backward,  and 
downward,  is  the  helix.1  Separated 
from  this  by  a  groove2  is  the  ridge 
named  the  antihelix,  which  bifur- 
cates above,3  and  includes  a  trian- 
gular fossa.4  In  front  of  the  audit- 
ory meatus  is  a  conical  eminence, 
the  tragus  ;5  and  separated  from 
this  by  a  rounded  notch,  and  situ- 
ated below  the  antihelix,  is  an- 
other eminence,  the  antitragus, 
The  deep  concavity  within  the  po- 
sition of  the  antihelix,  and  present- 
ing a  semispiral  course  toward  the 
entrance  of  the  auditory  meatus,  is 
the  concha. 

The  auricle,  excepting  its  lobe, 
consists  of  a  plate  of  fibro-cartilage, 
invested  with  a  perichondrium,  to 
which  the  skin  tightly  adheres. 
Several  fissures  or  intervals  exist  in 
the  fibro-cartilage,  occupied  by  con- 
nective tissue.  Thus  the  fibro-car- 
tilage is  deficient  between  the  tragus  and  the  commencement  of  the  he- 
lix, and  between  the  lower  end  of  the  latter  and  the  antitragus.  Short 
fissures  also  exist  on  the  tragus  and  the  fore  part  of  the  helix.  In  the 
last-mentioned  position  there  is  a  small  conical  eminence,  named  the 
process  of  the  helix. 

The  fibro-cartilage  of  the  auricle  is  thin,  and  rather  brittle,  but  is  ren- 
dered more  tenacious  by  its  perichondrium.  The  skin  is  thin,  and,  as 
elsewhere  generally,  is  furnished  with  minute  hairs  and  sebaceous  glands. 
The  latter  are  well  developed  in  the  fossaB  of  the  auricle,  more  especially 
in  the  concha. 

Besides  the  connection  of  the  skin,  the  auricle  is  attached  to  the  side 
of  the  head  by  ligamentous  bands.  The  anterior  ligament,  broad  and 
strong,  extends  from  the  process  of  the  helix  to  the  root  of  the  zygo- 


THE  AURICLE.  1,  helix;  2,  fossa  of  the  helix;  3, 
antihelix;  4,  fossa  of  the  antihelix;  5,  concha  sub- 
divided by  the  commencement  of  the  helix ;  6,  tra- 
gus; 7,  antitragus;  8,  entrance  of  the  external 
auditory  meatus ;  9,  the  lobe.  The  large  dots  in 
the  concha  and  fossa  of  the  autihelix  are  the  ori- 
fices of  sebaceous  glands. 


1  Capreolus. 

2  Fossa  navicularis,  scaphoides,  or  in- 


nominata;  fossa  of  the  helix. 
3  Crura  furcata. 


*  Fossa  of  the  antihelix;  fossa  trian- 
gularis,  or  ovalis. 
6  Hircus. 


614  THE   ORGANS   OF   SPECIAL   SENSE. 

matic  process.     The  posterior  ligament  attaches  the  convexity  of  the 
concha  to  the  root  of  the  mastoid  process. 

The  auricle  possesses  five  small  muscles  situated  between  the  fibro- 
cartilage  and  the  skin,  and  three  larger  ones  which  connect  it  with  the 
side  of  the  head.  They  are  all  composed  of  striated  fibres,  and  while 
the  function  of  the  former  is  very  obscure,  the  latter  are  generally  quite 
inactive. 

The  smaller  muscle  of  the  helix1  is  a  short  fasciculus  situated  on  the 
commencement  of  the  latter. 

The  greater  muscle  of  the  helix2  is  a  narrow  band  situated  on  the 
fore  part  of  the  auricle,  above  the  process  of  the  helix. 

The  muscle  of  the  tragus3  is  a  short  plane  of  fibres  situated  on  the 
outer  surface  of  the  tragus. 

The  muscle  of  the  antitragus4  is  a  band  extended  from  the  antitragus 
to  the  lower  extremity  of  the  helix. 

The  transverse  muscle,5  larger  than  the  preceding,  is  situated  on  the 
back  of  the  auricle,  and  consists  of  a  plane  of  fibres  extending  from  the 
concha  to  the  ridge  bounding  the  groove  of  the  antihelix. 

The  superior  auric'ular  muscle6  is  a  broad,  thin,  and  pale  fan-like 
plane  of  fibres,  arising  from  the  border  of  the  occipito-frontal  aponeu- 
rosis,  and  descending  to  be  inserted  back  of  the  fossa  of  the  antihelix. 
In  action,  it  will  draw  the  auricle  upward. 

The  anterior  auric'ular  muscle,7  generally  less  distinct  than  the  pre- 
ceding, is  a  thin,  transverse  fasciculus  arising  from  the  temporal  fascia, 
and  inserted  into  the  helix  and  concha.  In  action  it  would  draw  the 
auricle  forward. 

The  posterior  auric'ular  muscle,8  stronger  and  less  pale  than  the 
others,  consists  of  two  or  three  fasciculi  arising  from  the  mastoid  proc- 
ess, and  inserted  into  the  back  of  the  concha.  In  action  it  draws  the 
auricle  backward. 

The  auricle  is  abundantly  supplied  with  blood-vessels  and  nerves.     Its 

1  M.  helicis  minor.  7  M.  auricularis   anterior;    m.  attra- 

2  M.  helicis  major.  hens  auriculae;   m.    anterior  aims ;   m. 

3  M.  tragicus.  zygomato-auricularis. 

4  M.  antitragicus.  8  M.  auricularis  posterior;    m.  retra- 

5  M.  transversus  auriculae ;  m.  t.  and  hens,  or  retrahentes  auriculae ;  m.  pos- 
obliquus  auris.  terior   auris:    m.    mastoido-auricularis; 

6  M.  auricularis  superior;  m.  attollens  m.  deprimens  auriculae;   m.  bicaudalis, 
auriculae,  or  aurem;    m.  levator,  or  su-  triceps,   or   tricaudalis   auris;    m.   pro- 
perior  auris;  m.  temporo-auricularis.  prius  auris  externae;  m.  secundus  pro- 

priorum  auriculae. 


THE   ORGANS   OF   SPECIAL   SENSE!  615 

arteries  form  a  conspicuous  net-work  upon  the  fibro-cartilage,  and  are 
derived  from  the  anterior  and  posterior  auricular  branches  of  the  tem- 
poral and  external  carotid  arteries.  Its  veins  terminate  in  the  temporal 
vein.  The  nerves  are  derived  from  the  great  auricular  branch  of  the 
cervical  plexus,  the  posterior  auricular  branch  of  the  facial  nerve,  and 
the  auriculo-temporal  branch  of  the  inferior  maxillary  nerve. 

The  External  aud'itory  mea'tus1  is  a  canal  extending  from  the  concha 
to  the  tympanum,  and  serves  to  conduct  sounds  to  the  latter  which 

FIG.  370. 


GENERAL  VIEW  OF  THE  EAR,  RIGHT  SIDE,  LAID  OPEN  FROM  THE  FRONT.  1,  auricle;  2,  concha;  3,  4,  exter- 
nal auditory  meatus;  5,  ceruminous  glands;  6,  tympanic  membrane;  7,  anvil;  8,  mallet;  9,  its  handle 
inserted  into  the  tympanic  membrane;  10,  tensor  muscle  of  the  latter;  11,  cavity  of  the  tympanum:  12, 
Eustachian  tube;  13, 14, 15,  the  three  semicircular  canals;  16,  cochlea;  17,  the  internal  auditory  meatus: 
18,  facial  nerve  occupying  a  groove  of  the  auditory  nerve,  20,  21. 

are  collected  by  the  auricle.  It  is  about  an  inch  in  length,  is  directed 
inward  and  forward,  and  curves  in  its  course  upward  and  downward. 
Its  commencement  is  vertically  oval,  its  middle  is  the  narrowest  part, 
and  its  bottom  is  closed  by  the  tympanic  membrane. 

The  meatus  consists  of  an  outer  shorter  portion,  which  is  a  prolonga- 
tion of  the  auricle,  and  an  inner  portion  composed  of  the  osseous  audit- 
ory meatus  lined  with  an  extension  of  the  skin. 

The  outer  portion  of  the  meatus,  independently  of  the  skin,  is  com- 

1  Meatus  auditorius  externus;  external  auditory  canal;  auricular  canal;  alve- 
arium;  scapha. 


616  THE   ORGANS   OF   SPECIAL   SENSE. 

posed  of  a  scroll  of  fibro-cartilage,  open  above,  and  continuous  by  a  nar- 
row slip  with  that  of  the  auricle.  The  interval  of  the  scroll  is  occupied 
with  fibrous  membrane,  thus  producing  a  complete  tube.  The  fissures 
intervening  between  the  outer  part  of  the  latter  and  the  concha  are  like- 
wise occupied  with  fibrous  membrane,  and  its  inner  extremity  is  con- 
nected by  an  annular  ligament  with  the  orifice  of  the  osseous  rneatus. 

The  skin  of  the  outer  portion  of  the  auditory  meatus  is  comparatively 
thick,  and  is  furnished  with  numerous  hairs  and  sebaceous  glands.  Its 
surface  presents  a  punctated  appearance,  from  the  many  orifices  of 
the  ceru/minous  glands,1  which  secrete  the  ceru/men  or  ear-wax.2 
These  glands  are  small,  rounded  bodies,  of  a  brownish-yellow  color,  im- 
bedded in  the  subcutaneous  tissue.  They  consist  of  a  narrow  tube  con- 
voluted upon  itself  into  a  rounded  mass,  the  terminal  portion  of  the 
tube  penetrating  the  skin  as  the  duct  of  the  gland. 

The  inner  portion  of  the  auditory  meatus  corresponds  with  the  passage 
of  the  same  name  in  the  macerated  bone,  and  is  narrower  and  longer 
than  the  outer  portion.  The  skin  lining  it  is  very  thin,  is  unprovided 
with  hairs  or  glands,  and  becomes  continuous  with  the  structure  of  the 
tympanic  membrane  which  closes  the  bottom  of  the  meatus. 

The  blood-vessels  and  nerves  of  the  external  auditory  meatus  have  the 
same  derivation  as  those  of  the  auricle. 

THE  MIDDLE  EAE. 

The  Middle  ear  consists  of  the  tympanum,  together  with  its  inclosed 
bones,  their  ligaments  and  muscles,  and  the  mastoid  sinuses  and  Eusta- 
chian  tube. 

The  Tym'panum,  or  drum  of  the  ear,3  is  an  irregular  cavity  in  the  in- 
terior of  the  petrous  portion  of  the  temporal  bone.  It  is  about  half  an 
inch  in  height  and  breadth,  and  one  to"*  two  lines  from  without  inward. 
Its  roof  is  a  plate  of  bone  separating  it  from  the  cranial  cavity ;  its 
floor  is  a  groove  between  the  outer  and  inner  walls.  Into  its  upper  back 
part  open  the  mastoid  sinuses ;  and  in  front  it  narrows  into  the  Eusta- 
chian  tube.  The  outer  wall  is  formed  by  the  tympanic  membrane,  and 
its  inner  wall  bounds  the  labyrinth. 

The  tym'panic  membrane,  or  membrane  of  the  tym'panum,4  is  a  cir- 

1  Glandulae,  or  folliculae  ceruminosse.        the   ear;    antrum,    or    cavitas    antrosa 

2  Cerea;    sordes,   sordiculse,  or  mar-      auris. 

morata    aurium;     ceruminous    humor;  4  Membrana  tympani;    membrane   of 

cypsele,  or  cypselis;  fugile.  the  drum;  diaphragma,  mediastinum,  or 

3  Cavum,  or  cavitas  tympani;  cavity  tegumentum  auris;  myringa;  myrinx. 
of  the  tympanum,  or  drum;   barrel  of 


THE   ORGANS   OF   SPECIAL   SENSE. 

cular  partition  separating  the  cavity  of  the  tympanum  from  the  external 
auditory  meatus,  from  which  it  receives  transmitted  sounds.  It  is  not 
flat,  but  slightly  funnel  shaped,  and  is  situated  obliquely,  so  that  its 
outer,  depressed  surface1  is  directed  downward  and  forward.  The  greater 
part  of  its  circumference  is  inserted  into  a  fine  groove,  which  in  the  new- 
born child  is  included  by  an  osseous  ring,  subsequently  developed,  by 
prolongation  outwardly,  into  the  osseous  auditory  meatus.  Into  its 
upper  part,  descending  as  far  as  the  centre,  the  handle  of  the  mallet  is 
inserted,  so  that  vibrations  of  the  tympanic  membrane  are  communicated 
to  the  latter. 

The  tympanic  membrane  is  thin  and  translucent,  and  is  composed  of  a 
layer  of  fibrous  tissue  invested  externally  with  a  continuation  of  the  epi- 
dermis of  the  meatus,  and  internally  with  an  extension  of  the  lining  mu- 
cous membrane  of  the  tympanum.  Its  fibrous  layer  consists  of  fibres 
radiating  from  the  centre,  with  some  concentric  fibres  at  its  circumference. 

FIG.  371. 


CAVITY  OF  THE  TYMPANUM  AND  MASTOID  SINUSES,  right  side.  The  auditory  meatus,  tympanic  mem- 
brane, small  bones,  and  outer  wall  of  the  mastoid  sinuses  removed.  1,  promontory;  2,  pyramid;  3,  ridge 
within  which  descends  the  Fallopian  canal;  4,  round  window;  5,  oval  window;  6,  osseous  portion  of  the 
Eustachian  tube;  7,  surface  of  attachment  of  the  cartilage  of  the  latter;  8,  canal  above  the  tube  which 
lodges  the  tensor  muscle  of  the  tympanum ;  9,  Fallopian  canal  laid  open ;  10,  canal  occupied  by  the 
greater  petrous  nerve;  11,  mastoid  sinuses;  12,  communication  of  the  latter  with  the  tympanum;  13, 
orifice  through  which  the  tympanic  branch  of  the  facial  nerve  enters  the  tympanum. 

The  inner  wall  of  the  tympanum  presents  a  convex  eminence,  the 
prom'ontory,2  produced  by  the  projection  of  the  cochlea.     Above  the 

1  Umbo.  2  Promontorium ;  tuber,  or  tuberositas  tympani. 


618 


THE  ORGANS  OF   SPECIAL   SENSE. 


back  of  the  promontory  is  an  orifice,  the  oval  window,1  which  communi- 
cates with  the  vestibule,  but  is  closed  by  the  application  of  the  base  of 
the  stirrup.  Above  the  oval  window  and  promontory  is  a  ridge,  pass- 
ing from  before  backward,  produced  by  the  course  of  the  Fallopian 
canal,  which  transmits  the  facial  nerve.  Behind  the  lower  part  of  the 
promontory  is  a  pit,  at  the  bottom  of  which  is  an  aperture  named  the 
round  window.2  This  communicates  with  the  cochlea,  but  is  closed  by 
the  secondary  tym/panic  membrane,3  which  consists  of  a  fibrous  layer, 
invested  externally  with  the  lining  membrane  of  the  tympanum,  inter- 
nally with  that  of  the  cochlea. 

At  the  back  part  of  the  tympanum  a  descending  ridge  indicates  the 
continuation  of  the  Fallopian  canal  to  the  stylo-mastoid  foramen.  From 
the  ridge  there  projects  forward  a  hollow,  conical  eminence,  named  the 
pyramid,4 


The  small  bones5   occupy  the  upper  part 


FIG.  372. 

4  5 


SMALL  BONES  OF  THE  EAR.  1.  Mallet  seen  on  its  inner  surface. 
a,  head;  b,  articular  surface  for  the  anvil;  c,  handle;  d,  the  long 
process.  2.  Mallet  seen  on  its  outer  surface,  a,  head ;  b,  articu- 
lar surface;  c,  handle;  d,  long  process;  e,  short  process.  3.  Mal- 
let seen  from  behind,  a,  head  and  articular  facet;  b,  short  proc- 
ess; c,  long  process.  4.  Anvil  seen  on  its  inner  surface,  a, 
body ;  b,  articular  facet  for  the  mallet ;  c,  short  process ;  d,  long 
process;  e,  orbicular  process.  5.  Anvil  seen  on  its  outer  surface. 
a,  body ;  b,  articular  facet ;  c,  d,  short  and  long  processes.  6.  Or- 
bicular process,  at  birth  a  distinct  bone.  7.  Stirrup,  a,  head;  b,  c, 
crura;  d,  base.  8.  Base  of  the  stirrup,  which  is  applied  to  the 
oval  window.  9.  Stirrup  cut  so  as  to  exhibit  the  groove  on  the 
inner  side  of  its  crura  a. 

the  fibrous  layer  of  the  tympanic  membrane 


of  the  tympanum,  and  are 
named,  from  their  resem- 
blance, the  mallet,  anvil, 
and  stirrup.  Articulating 
movably  with  one  an- 
other in  the  order  given, 
the  mallet  is  attached  to 
the  tympanic  membrane, 
and  the  stirrup  communi- 
cates with  the  oval  win- 
dow, so  that  the  vibra- 
tions of  the  former  are 
continued  through  the  se- 
ries of  bones  to  the  latter. 
The  Mallet6  is  situated 
vertically,  with  its  head 
lodged  in  the  upper  part 
of  the  tympanum,  and  its 
handle  descending  into 

as  far  as  its  centre.     The 


1  Fenestra  ovalis,  or  vestibularis ;  fora- 
men ovale. 

2  Fenestra  rotunda,  triquetra,  or  coch- 
learis;  foramen  rotundum. 

3  Membrana  tympani  secnndaria;  m. 
fenestras  rotundae ;  tympanum  minus,  or 
secundarium. 


4  Pyramis;    eminent  i  a   pyramidalis 
tympani. 

5  Ossiculi  auditus;  o.  auris. 

e  Malleus,  malleolus;   ossiculum  mal- 
leolo-assimilatum;  the  hammer. 


THE   ORGANS   OF   SPECIAL   SENSE.  619 

head  is  rounded,  and  at  its  back  part  has  an  oval  facet  invested  with 
cartilage,  for  articulation  with  the  anvil.  The  handle1  is  a  tapering 
process,  slightly  twisted  and  compressed.  The  neck  is  slightly  con- 
stricted, and  gives  off  two  processes.  The  long  process2  is  a  slender 
spine  projecting  nearly  at  a  right  angle  from  the  neck,  and  enters  the 
glenoid  fissure  ;  the  short  process3  is  a  conical  eminence  at  the  root  of 
the  neck. 

The  Anvil4  is  situated  behind  the  mallet,  near  the  entrance  to  the  mas- 
toid  sinuses.  Its  body  is  irregularly  square,  and  at  its  fore  part  has  an 
oval  articular  surface  for  the  head  of  the  mallet.  Behind,  it  has  a  pair 
of  diverging  processes,  of  which  the  lower  is  the  longer.  The  short 
process3  projects  backward,  and  is  connected  by  a  ligamentous  band  to 
the  posterior  part  of  the  tympanum.  The  long  process6  is  curved  and 
tapering,  and  descends  nearly  parallel  to  the  handle  of  the  mallet.  Its 
end  internally  supports  an  orbicular  process,7  which  articulates  with 
the  head  of  the  stirrup.  At  birth  the  latter  process  is  a  distinct  bone, 
but  it  soon  becomes  co-ossified  with  the  anvil. 

The  Stirrup8  is  directed  horizontally  inward  from  the  anvil  to  the  oval 
window.  Its  head  is  flattened,  and  at  the  summit  has  a  concave  artic- 
ular facet,  invested  with  cartilage,  for  the  orbicular  process  of  the  anvil. 
From  the  head  a  pair  of  crura  curve  inwardly  to  join  the  base,  which  is 
applied  to  the  oval  window. 

The  three  bones  just  described  have  movable  articulations,  surrounded 
by  a  capsular  ligament  and  lined  with  synovial  membrane.  The  articu- 
lation between  the  mallet  and  anvil  is  hinge  like;  that  between  the  latter 
bone  and  the  stirrup  is  a  ball-and-socket  joint. 

The  suspensory  ligament9  of  the  mallet  is  a  slender  band  of  fibres, 
extending  from  the  head  of  the  bone  to  the  roof  of  the  tympanum. 

The  suspensory  ligament10  of  the  anvil  extends  from  its  short  process 
to  the  back  part  of  the  tympanum. 

The  annular  ligament11  of  the  stirrup  connects  the  margin  of  the  base 
with  the  border  of  the  oval  window. 

1  Manubrium.  7  QS,  or  ossiculum  orbiculare,  lenticu- 

2  Processus,  or  apophysis  longus,  gra-  lare,  squamosum,  cochleare,  or  quartum; 
cilis,  Folii,  or  Rauii.  processuslenticularis;  ossiculum  orbicu- 

3  P.  brevis;  p.  obtusus.  lare  or  lenticulare  Sylvii;  globulus  sta- 

4  Incus;  acmon;  os  incude  simile;  os-  pedis;  epiphysis  cruris  longioris  incudis. 
siculum  incudi,  or  molari  denti  compa-  8  Stapes ;  stapha ;  staffa. 

ratum.  »  Ligamentum  superiores,  or  teres. 

5  Ramus  horizontals.  10  Posterior  ligament. 

6  Ramus  verticalis.  »  L.  annulare,   or   orbiculare  baseos 

stapedis. 


620  THE   ORGANS   OF   SPECIAL   SENSE. 

Three  minute  muscles,  composed  of  striated  fibre,  are  connected  with 
the  bones  of  the  ear,  to  regulate  their  movements.  Others1  have  been 
described,  but  their  existence  is  not  usually  acknowledged. 

The  tensor  muscle2  arises  from  the  end  of  the  cartilage  of  the  Eusta- 
chian  tube  and  the  contiguous  surfaces  of  the  sphenoid  and  temporal 
bone.  Passing  through  an  osseous  canal  of  the  latter,  above  the  Eusta- 
chian  tube,  it  ends  in  a  tendon  which  enters  the  tympanum  and  turns 
outwardly  to  be  inserted  into  the  neck  of  the  mallet.  Its  contraction 
increases  the  tensity  of  the  tympanic  membrane. 

The  laxa'tor  muscle3  arises  from  the  spinous  process  of  the  sphenoid 
bone,  passes  upward  and  outward,  and  enters  the  glenoid  fissure,  to  be 
inserted  into  the  long  process  of  the  mallet.  In  action  it  relaxes  the 
tympanic  membrane. 

The  stape'dius  muscle4  arises  within  the  hollow  of  the  pyramid,  and 
is  inserted  into  the  head  of  the  stirrup.  It  regulates  the  pressure  of  the 
base  of  the  latter  against  the  oval  window. 

The  cavity  of  the  tympanum  is  everywhere  lined  with  a  delicate  mu- 
cous membrane,  which  likewise  invests  the  small  bones,  stretching  across 
the  aperture  of  the  stirrup,5  and  covering  the  muscles  and  ligaments.  It 
is  pink  in  color  from  its  vascularity,  and  is  provided  with  a  pavement- 
like  epithelium.  The  arteries  of  the  tympanum,  though  small,  are  nu- 
merous. They  are  derived  from  the  tympanic  branch  of  the  internal 
maxillary  artery,  the  stylo-mastoid  artery,  the  great  meiiingeal  and  de- 
scending palatine  arteries,  and  from  the  internal  carotid  artery  as  it 
passes  through  the  carotid  canal.  The  veins  communicate  with  the  great 
meningeal  and  pharyngeal  veins,  and  through  a  plexus,  near  the  glenoid 
articulation,  with  the  internal  jugular  vein.  The  nerves  are  derived  from 
the  tympanic  branch  of  the  glosso-pharyngeal,  and  the  carotid  plexus  of 
the  sympathetic  nerve. 

The  Mastoid  sinuses6  consist  of  numerous  irregular  cavities  in  the 
interior  of  the  mastoid  portion  of  the  temporal  bone,  communicating  by 
a  large  orifice7  with  the  upper  back  part  of  the  tympanum.  They  are 

1   Laxator  tympani  minor.  ternus;  m.  Eustachii;  m.  spheni-salpin- 

3  M.  tensor    tympani;    m.   internus  go-mallei. 

mallei;    m.   tensor   auris  internus;    m.  4  M.  stapedius,  or  pyramo-stapedius. 

salpingo-mallei.  5  Membrana  obturatoria,  or  propria 

8  M.  laxator  tympani;  m.  1.  t.  major;  stapedis. 

anterior  ligament  of  the  malleus;    m.          6  Mastoid  cells;    cellulse  mastoidese; 

mallei  externus,  or  anterior;  m.  obliquus,  antrum  mastoideum. 
or  externus  auris;  m.  laxator  auris  in-          7  Petro-mastoid  canal. 


THE  ORGANS  OF  SPECIAL  SENSE.  621 

lined  throughout  with  a  delicate  mucous  membrane,  provided  with  a  pave- 
ment epithelium. 

The  Eusta'chian  tube1  is  a  trumpet-shaped  canal,  rather  over  an  inch 
and  a  half  long,  extending  from  the  fore  part  of  the  tympanum  obliquely 
inward,  forward,  and  downward  to  the  pharynx.  Its  upper  section  is 
formed  by  an  osseous  canal  in  the  petrous  portion  of  the  temporal  bone, 
which  communicates  at  its  outer  end  with  the  tympanum,  and  narrows 
to  its  union  with  the  other  section  in  the  angle  between  the  squamous 
and  petrous  portions  of  the  temporal  bone. 

The  lower  and  longer  section  of  the  Eustachian  tube  proceeds  from 
the  angle  mentioned  along  the  posterior  border  of  the  sphenoid  bone  to 
the  inner  side  of  the  internal  pterygoid  process.  Gradually  expanding 
in  its  course,  it  terminates  by  an  oval  orifice,  with  a  prominent  border,  at 
the  side  of  the  pharynx,  on  a  level  with  the  turbinated  bone,  just  back 
of  the  posterior  nasal  orifice.  It  is  composed  of  a  triangular  plate  of 
cartilage,  bent  into  a  gutter,  open  at  its  outer  part,  but  converted  into  a 
complete  tube  by  fibrous  membrane. 

The  Eustachian  tube  is  lined  with  mucous  membrane,  provided  with  a 
ciliated  epithelium,  and  is  continuous  with  that  of  the  pharynx  and  tym- 
panum. 

THE  INTERNAL  EAE. 

The  Internal  ear  includes  the  labyrinth  and  the  internal  auditory 
meatus. 

The  Lab'yrinth,2  named  from  its  highly  complex  character,  is  the  most 
important  portion  of  the  organ  of  hearing,  as  it  contains  the  entire  dis- 
tribution of  the  auditory  nerve.  It  is  imbedded  in  the  petrous  portion 
of  the  temporal  bone,  and  consists  of  three  parts,  named  the  vestibule, 
the  semicircular  canals,  and  the  cochlea.  Though  these  may  be  des- 
cribed as  cavities,  it  should  be  understood  that  the  labyrinth  has  os- 
seous walls  independent  of  the  bony  structure  embracing  it.  At  birth 
it  may  be  readily  excavated  from  the  looser  surrounding  osseous  sub- 
stance ;  but  at  a  later  period  this  substance  becomes  condensed  and 
confounded  with  the  exterior  surface  of  the  labyrinth. 

The  Ves'tibule3  is  an  irregularly  oval  cavity,  situated  between  the 
tympanum  and  the  bottom  of  the  internal  auditory  meatus,  and  joining 

1  Tuba  Eustachiana,  or  Aristotelica ;  2  Labyrinthus ;  1.  auris  intimae ;  laby- 

canalis  gutteralis ;    meatus  csecus :  Her  rintliic  cavity ;  pars  intiraa  organ!  audi- 

a  palato  ad  aurem ;  ductus  auris  palati-  tus ;  antrum  buccinosum. 

nus;  syrinx;    syringa.  3  Vestibulum  labyrinth!. 


622 


THE   ORGANS   OF   SPECIAL   SENSE. 


FIG 


the  semicircular  canals  postero-externally,  the  cochlea  antero-internally. 
Through  its  outer  wall  it  communicates  with 
the  tympanum  by  the  oval  window. 

A  slight  semicircular  ridge  or  crest1  springs 
from  the  floor  of  the  vestibule,  ascends  on 
its  inner  wall  to  the  roof,  and  terminates  in 
a  small  pyramidal  eminence.2  The  latter 
presents  a  group  of  minute  foramina  commu- 
THE  INTERNAL  EAR,  CONSISTING  OF  nicating  with  the  internal  auditory  meatus,  and 

THE  LABYRINTH  AND  INTERNAL  AUD-  name(J  ^6  SUpCnOr  CriVrifbrHl  SpOt.3  TllC 
ITORT  MEATUS,  LAID  OPEN.  The  lower 

part  of  the  figure  exhibits  the  three  crest  separates  two  recesses,  called,  from  their 
osseous  semicircular  canals  con-  shape,  the  hemispherical4  and  hemielliptical 

taining  the  membranous  semicir-  . 

cuiar  canals,  i,  2,  two  semidrcu-  fossa.5  The  former  is  the  smaller,  and  occu- 
iar  canals,  ending  in  a  common  pjes  the  antero-internal  portion  of  the  vesti- 

tube,  3;  4,  simple  extremity  of  one     ,      - 

of  the  canals;  5, 6, 7,  dilated  ex-    bule  ;  the  latter  occupies  the  postero-external 

tremeties  or  ampullae  of  the  canals;      portion.         Just    below  the  Centre   of  the    hemi- 

S,  elliptical,  and  9,  hemispherical  -i       •      i    f  •  /» 

saccules  contained  in  the  vestibule.      Spherical    fossa    IS    a    SCCOnd    group    of    minute 

Above  the  latter  is  the  cochlea;    foramina    communicating    with    the    internal 

and  to  its  left  the  internal  auditory  -,.,  -,    ,-.  .  ,  ,»  .,  , 

meatus  auditory  meatus,  and  named  the  middle  criV- 

riform  spot.6     Immediately  in  advance  of  the 

fossa,  the  orifice7  of  the  vestibular  scala  of  the  cochlea  communicates 
with  the  vestibule.  Into  the  hemielliptical  fossa  open  the  orifices  of  the 
semicircular  canals  and  the  aperture8  of  a  small  vascular  canal9  which 
communicates  with  the  posterior  surface  of  the  petrous  portion  of  the 
temporal  bone,  and  transmits  the  vestibular  vein  to  the  inferior  petrosal 
sinus. 


The  Semicircular  canals,10  three  in  number,  are  situated  postero-ex- 
ternally to  the  vestibule  and  above  the  inner  back  part  of  the  tympanum. 
From  their  position  they  are  named  superior,11  posterior,12  and  infe- 
rior;13 the  former  two  being  vertical,  the  last  horizontal.  They  are  so 


1  Crista  vestibuli. 

2  Eminentia    pyramidalis ;     pyramis 
vestibuli. 

8  Macula  cribrosa  superius. 
*  Fossa,  or  fovea  hemispherica ;  re- 
cessus  hemisphericus ;   sinus  rotundus. 

5  Fossa,  or  fovea  hemielliptica,  semi- 
elliptica,  or  elliptica;  recessus  hemiel- 
lipticus;   sinus  ovatus. 

6  Macula  crfbrosa  media. 

7  Apertura  scalaa  vestibuli. 


8  Recessus,  or  fovea  sulciformis. 

9  Aqueduct  of  the  vestibule ;    aquas- 
ductus  vestibuli,  or  Cotunnii ;    canal  of 
Cotunnius. 

10  Canales,  or  ductus  semicirculares, 
circulares,  or  tubaeformes;  semicircular! 
ossei;  funes,  or  canaliculi  semicirculares 
labyrinthi. 

11  Also  vertical,  or  superior  vertical. 

12  Also  posterior  vertical,  or  oblique. 

13  Also  external,  or  horizontal. 


THE  ORGANS  OF  SPECIAL  SENSE.  623 

related  with  one  another  as  to  correspond  with  the  inner,  back,  and 
lower  faces  of  a  cube. 

Each  canal  is  rather  more  than  half  a  circle,  and  forms  at  one  extremity 
a  bottle-like  dilatation,  named  the  ampulla,  which  communicates  with  the 
vestibule.  Of  the  undilated  extremities,  two  conjoin,  and,  with  the  re- 
maining extremity,  likewise  open  into  the  vestibule  ;  and  thus  the  three 
canals  communicate  with  the  latter  by  five  orifices. 

Within  the  ampulla  of  the  posterior  semicircular  canal  there  is  a  third 
group  of  minute  foramina  communicating  with  the  internal  auditory 
meatus,  and  named  the  inferior  cribriform  spot.1 

The  interior  of  the  vestibule  and  the  semicircular  canals  is  lined  with- 
a  delicate  membrane,  resembling  a  serous  membrane.  It  consists  of  a 
fibrous  layer  adhering  to  the  osseous  surface  as  a  periosteum,  a  structure- 
less basement  layer,  and  a  tessellated  epithelium.  Within  this  mem- 
brane the  cavity  is  occupied  by  a  serous  liquid,  named  the  perilymph,2 
from  its  surrounding  a  secondary  structure,  known  as  the  membranous 
lab'yrinth,  This  consists  of  a  pair  of  communicating  pouches,3  con- 
tained in  the  vestibule,  and  three  semicircular  canals,  of  the  same  form 
as  the  osseous  canals  which  contain  them.  The  smaller  pouch  occupies 
the  hemispherical  fossa,  and  is  named  the  spherical  saccule  ;4  while  the 
other  pouch,  occupying  the  hemielliptical  fossa,  is  named  the  elliptical 
saccule,5  and  is  joined  by  three  membranous  semicircular  canals. 

The  membranous  labyrinth  consists  of  an  outer  fibrous  structure,  lined 
internally  with  a  tessellated  epithelium,  and  filled  with  a  serous  liquid, 
named  the  endolymph.6 

The  vestibular  branch  of  the  internal  auditory  nerve  is  distributed 
to  the  membranous  labyrinth,  and  maintains  its  floating  position  in 
the  perilymph.  This  nerve  divides  at  the  bottom  of  the  internal  aud- 
itory meatus  into  three  branches,  of  which  one  enters  the  vestibule 
at  the  superior  cribriform  spot,  to  be  distributed  to  the  elliptical  sac- 
cule and  the  ampullae  of  the  superior  and  inferior  semicircular  canals ; 
a  second  enters  at  the  middle  cribriform  spot,  and  is  distributed  to  the 


1  Macula  cribrosa  inferius.  utriculus,  sinus,  or  alveus  communis ; 

2  Liquor,  or  aquula  Cotunnii;  aqua,  utricle;    sinus,    or   alveus   utriculosus; 
or  aquula  acustica,  or  auditoria;  aquula.  median  sinus. 

3  Sacculus  vestibuli.  «  Endolympha;  vitrina  auditiva;  aqu- 

4  Sacculus  sphaericus ;  sacculus ;  sac-  ula   vitrea    auditiva ;     aqua    labyrinth! 
cule.  membranacei ;    humor    vitreus   auris; 

5  Sacculus    ellipticus ;    s.    vestibuli ;  liquor  of  Scarpa. 


624  THE   ORGANS  OF  SPECIAL   SENSE. 

hemispherical  saccule ;  and  the  third  enters  at  the  inferior  cribriform  spot, 
and  is  distributed  to  the  ampulla  of  the  posterior  semicircular  canal. 


FIG.  374. 


fig.  374. — INTERNAL  EAR  LAID  OPEN.  1,  vestibular  branch  of  the  auditory  nerve ;  z,  branch  to  the 
spherical  saccule ;  3,  branch  to  the  elliptical  saccule ;  4,  5,  6,  branches  to  the  ampulla}  of  the  membranous 
semicircular  canals;  7,  cochlear  branch  of  the  auditory  nerve;  8,  cochlea. 

Fig.  375. — NERVES  OF  THE  VESTIBULE  AND  SEMICIRCULAR  CANALS,  magnified  three  diameters.  1,  vestibular 
branch  of  the  auditory  nerve;  2,  branch  to  the  spherical  saccule;  3,  branch  to  the  elliptical  saccule; 
4,  5,  6,  branches  to  the  ampullae  of  the  semicircular  canals ;  7,  cochlear  nerve. 

Adhering  to  the  inner  surface  of  the  two  saccules  of  the  vestibule,  at 
the  point  of  entrance  of  the  nervous  filaments  from  the  cribriform  spots, 
are  two  white  discoidal  masses,  consisting  of  minute  crystalline  particles, 
called  o'tolites,1  These  cohere,  and  appear  to  be  in  contact  with  the 
nervous  filaments  distributed  to  the  saccules.  They  are  composed  of 
carbonate  of  lime,  and  are  an  important  element  of  structure  to  the 
organ  of  hearing,  as  they  are  found  in  the  ear  of  most  animals. 

The  arteries  of  the  vestibule  and  semicircular  canals  are  derived  from 
the  vestibular  branches  of  the  auditory  artery  accompanying  the 
branches  of  the  vestibular  nerve.  The  veins  partly  terminate  in  the 
venous  sinus  of  the  cochlea,  and  partly  in  the  vestibular  vein,  which 
communicates  with  the  inferior  petrosal  sinus. 

The  Coch/lea2  is  the  inner  portion  of  the  labyrinth,  and  is  named  from 
its  resemblance  to  a  snail-shell.  Its  base  is  applied  to  the  bottom  of  the 
internal  auditory  meatus,  and  its  apex  is  directed  forward  and  slightly 
outward.  It  consists  of  an  osseous  tube,  about  an  inch  and  a  half 
long,  wound  nearly  three  times  around  a  central  axis,  with  each  turn  suc- 
cessively rising.  The  commencement  of  the  tube  is  connected  with 
the  fore  part  of  the  vestibule,  and  produces  the  promontory  of  the 

10tolithi;  otoliths;   otoconia;  otoconites. 

2  Concha  auris  interna;  c.  labyrinth!;  cavitas  cochleata,  or  buccinata;  trochlea 
labyrinth! ;  antrum  buccinosum. 


THE   ORGANS   OF   SPECIAL   SENSE. 


625 


tympanum.  Turning  from  right  to  left  in  the  right  ear,  and  the  reverse 
direction  in  the  left  ear,  it  ends  in  a  closed  extremity,  named  the  cupola, 
which  nearly  reaches  the  front  surface  of  the  petrous  portion  of  the  tem- 
poral bone  above  the  ascending  part  of  the  carotid  canal. 


FIG.  376. 


FIG.  377. 


THE  COCHLEA,  LAID  OPEN,  ITS  SUMMIT  TURNED  UP- 
WARD, magnified  three  diameters.  1,  2,  3,  the  tym- 
panic scala ;  4,  5,  6,  the  vestibular  scala ;  7,  8,  os- 
seous spiral  lamina;  9,  membranous  spiral  lamina; 
10,  orifice  of  communication  of  the  two  scalar  at  the 
summit  of  the  cochlea;  11,  12,  termination  of  the 
osseous  and  membranous  spiral  laminae. 


*    1  6  4  2      S35  71 


THE    COCHLEA,  LAID  OPEN,    AND  VIEWED    FROM    IT 8 
SUMMIT   TOWARD   THE    BASE.      1,  Cut  edges  of  the  Of~ 

seous  wall  of  the  cochlea ;  2,  osseous  spiral  lamina, 
seen  within  the  vestibular  scala;  3,  end  of  the 
lamina;  4,  5,  its  outer  border;  6,  membranous 
spiral  lamina;  7,  its  end;  8,  foramen  of  communi- 
cation with  the  tympanic  scala. 


The  axis  of  the  coch/lea1  is  conical,  its  base  forming  the  spiral  tract 
at  the  bottom  of  the  internal  auditory  meatus,  and  its  summit  becoming 
continuous  with  the  inner  wall  of  the  last  turn  of  the  canal  of  the 
cochlea.2  It  is  traversed  by  numerous  fine  canals,  continuous  with  the 
foramina  of  the  spiral  tract  and  transmitting  the  filaments  of  the  coch- 
lear  nerve,  together  with  the  cochlear  branches  of  the  auditory  artery. 
A  central  canal,3  larger  than  the  others,  extends  the  entire  length  of  the 
axis,  and  transmits  a  branch  of  the  latter  vessel. 

An  osseous  spiral  lamina4  commences  just  below  the  hemispherical 
fossa  of  the  vestibule,  winds  around  the  axis  of  the  cochlea,  extending 
about  half  way  across  its  canal,  and  terminates  in  a  pointed  process5  at 
the  summit  of  the  latter.  The  lamina  is  traversed  by  a  multitude  of 
fine  anastomosing  canals,  which  are  continuous  with  those  of  the  axis  of 
the  cochlea,  and  open  into  a  groove  at  the  free  margin  of  the  lamina. 


1  Column  of  the  cochlea ;  axis,  colu- 
mella,  or  pyramis  cochleae ;  modiolus. 

2  The  last  turn  of  the  inner  wall  of  the 
cochlea  upon  its  axis  forms  the  infun- 
dibulum,  or  scyphus  Vieussenii,  or  au- 
ditorius. 


3  Canalis  centralis  modioli. 
*  Lamina  spiralis  ossea;  septum  scalae, 
or  cochlae  auditorine ;  zona  ossea. 
5  Hamulus. 


40 


626  THE   ORGANS   OF  SPECIAL   SENSE. 

The  interior  of  the  cochlea  is  lined  by  a  delicate  membrane  continu- 
ous with,  and  like  that  of  the  vestibule.  After  investing  the  two  sur- 
faces of  the  osseous  spiral  lamina,  it  is  extended  in  a  double  layer  from 
the  free  border  of  the  latter  across  the  canal  of  the  cochlea  to  the  outer 
wall,  where  it  is  firmly  attached.  This  extension  of  the  membrane, 
which  is  named  the  membranous  spiral  lamina,1  together  with  the  osseous 
spiral  lamina,  divides  the  canal  of  the  cochlea  into  two  distinct  pas- 
sages, which  communicate  with  each  other  only  at  the  summit  of  the 
cochlea.2  At  the  lower  extremity  of  the  latter,  one  of  the  passages 
terminates  at  the  round  window  of  the  tympanum,  and  is  thence  named 
the  tym/panic  sca'la,3  while  the  other  opens  into  the  vestibule,  and  is 
called  the  vestib'ular  sca'la,4 

Both  scalae5  of  the  cochlea  are  filled  with  a  limpid  serous  liquid,  which 
communicates  with  the  perilymph  of  the  vestibule,  but  is  prevented  from 
escaping  at  the  round  window  by  the  secondary  tympanic  membrane. 

The  axis  of  the  cochlea  within  the  tympanic  scala  is  pierced  with  a 
series  of  foramina,  transmitting  veins  from  the  lining  membrane  of  the 
cochlea  to  a  spiral  sinus6  within  the  axis.  At  the  lower  extremity  of  the 
same  scala  is  the  orifice  of  a  canal7  which  ends  in  a  triangular  pit  in  ad- 
vance of  the  jugular  foramen,  and  transmits  a  vein  from  the  spiral  sinus 
just  mentioned  to  the  inferior  petrosal  sinus. 

The  cochlear  branch  of  the  internal  auditory  nerve  is  resolved  into  a 
multitude  of  filaments,  which,  together  with  branches  of  the  correspond- 
ing artery,  enter  the  foramina  of  the  spiral  tract  at  the  bottom  of  the 
internal  auditory  meatus.  Ascending  the  canals  of  the  axis  of  the 
cochlea,  they  are  reflected  outwardly  to  the  osseous  spiral  lamina, 
within  which  they  form  an  intricate  plexus,  and  become  associated 
near  its  free  border  with  a  series  of  nerve  cells.  From  these  the  nerve 
fibres  emerge,  and  enter  the  membranous  spiral  lamina,  where,  with  pe- 


1  Lamina  spiralis  membranacea;  zona  3  Scala  tympani,  posterior,  interna,  or 
membranacea,  or  mollis;  zona  choriacea  superior;  incorrectly  inferior. 

and  pars  membranacea;  z.  cartilaginea  4  Scala  vestibuli,  anterior,  externa,  or 

and  membranacea;  z.  media  and  mem-  inferior;  incorrectly  superior, 

branacea;  z.  nervea  and  cartilaginea;  z.  5  Gyri;  ductus  spirales;  canales. 

denticulata  and  pectinata;  habenula  in-  6  The  canal  containing  the  sinus  is  the 

terna,  or  sulcata,  and  h.  externa,  den-  canalis   Rosenthalianus,    or   c.    spiralis 

ticulata,  or  perforata,  are  subdivisions  modioli. 

of  the  zona  denticulata.  7  Aqueduct  of  the  cochlea;  aquseductus 

2  The  communication  is  named  the  cochleae. 
Helicotrema. 


,      THE   ORGANS   OF   SPECIAL   SENSE.  627 

culiar  nerve  cells,  they  form  a  complex  arrangement,  the  character  of 
which  has  not  yet  been  conclusively  determined.1 

FIG.  378. 


DISTRIBUTION  OF  THE  COCHLEAE,  NERVE.  1,  trunk  of  the  cochlear  nerve;  2,  membranous  spiral  lamina  ; 
3.  terminal  filaments  of  the  cochlear  nerve  emerging  from  the  osseous  spiral  lamina  to  spread  themselves 
in  the  membranous  lamina;  4,  orifice  of  communication  of  the  tympanic  and  vestibular  scalas. 

The  arteries  of  the  cochlea  are  mainly  derived  from  the  cochlear 
branches  of  the  auditory  artery,  and,  as  previously  indicated,  they  follow 
the  course  of  the  cochlear  branch  of  the  auditory  nerve  They  term- 
inate  in  a  capillary  net  of  the  lining  membrane  and  spiral  lamina  of  the 
cochlea,  from  which  veins  originate  and  join  the  spiral  venous  sinus 
within  the  axis  of  the  cochlea.  The  spiral  sinus  communicates  by  means 
of  a  vein  with  the  inferior  petrosal  sinus. 

The  Internal  aud/itory  mea'tus2  is  a  cylindroid  canal  about  three- 
fourths  of  an  inch  in  length,  leading  from  the  posterior  surface  of  the 
petrous  portion  of  the  temporal  bone,  obliquely  downward,  forward,  and 
outward  to  the  position  of  the  labyrinth.  Its  bottom  is  unequally  di- 
vided by  a  prominent,  transverse,  crescentic  crest  into  two  compartment?, 
of  which  the  lower  is  the  larger.  The  upper  compartment  is  subdivided 
by  a  vertical  ridge  into  two  pits,  of  which  the  inner  one  is  the  com- 
mencement of  the  Fallopian  canal  for  the  transmission  of  the  facial 
nerve,  and  the  outer  one  corresponds  with  the  superior  cribriform  spot 
of  the  vestibule  for  the  transmission  of  the  superior  division  of  the  ves- 


1  For  a  more  intimate  description  of  this  structure  see  the  admirable  researches 
of  Corti  and  Kolliker. 

2  Meatus  auditorius  interims;  foramen,  porus,  or  sinus  acusticus. 


628  THE   ORGANS   OF   SPECIAL   SENSE. 

tibular  nerve  to  the  elliptical  saccule.  The  lower  compartment  inter- 
nally is  occupied  by  a  spiral  tract,1  pierced  with  a  multitude  of  minute 
foramina,  for  the  transmission  of  the  cochlear  nerve;  externally  is  a 
fossa  corresponding  with  the  middle  cribriform  spot  for  the  transmission 
of  the  inferior  division  of  the  vestibular  nerve  to  the  hemispherical  sac- 
cule and  ampullae  of  the  superior  and  inferior  semicircular  canals.  In 
the  posterior  wall  of  the  meatus  there  is  a  small  canal,  transmitting  the 
posterior  division  of  the  vestibular  nerve  to  the  inferior  cribriform  spot 
of  the  ampulla  of  the  posterior  semicircular  canal. 

The  auditory  meatus  transmits  the  auditory  and  facial  nerves,  and  the 
auditory  artery.  The  facial  nerve  enters  the  Fallopian  canal,  and 
pursues  its  course  to  emerge  at  the  stylo-mastoid  foramen.  The 
auditory  nerve  divides  into  two  branches,  the  cochlear  and  vestiVular 
nerves.  The  former  resolves  itself  into  numerous  filaments,  which  enter 
the  foramina  of  the  spiral  tract  to  be  distributed  in  the  manner  indicated. 
The  vestibular  nerve  divides  into  three  branches,  which  resolve  them- 
selves into  many  filaments  transmitted  through  the  foramina  of  the  three 
cribriform  spots  as  above  mentioned. 

The  auditory  artery,  a  branch  of  the  basilar,  divides  into  cochlear  and 
vestibular  branches,  which  accompany  the  corresponding  nerves. 

THE  ORGAN  OF  TASTE. 

(For  an  account  of  the  organ  of  taste,  the  student  is  referred  to  the 
description  of  the  tongue,  page  280.) 

THE  SKIN  AND  ITS  APPENDAGES. 

The  Skin2  is  the  organ  of  touch,3  and  in  the  healthy  condition  of  the 
body  is  among  the  most  sensitive  to  the  impression  of  pain,  through 
which  quality  we  are  led  to  avoid  agencies  injurious  or  destructive  to 
life.  By  its  peculiar  constitution  it  prevents  evaporation  of  the  liquids 
of  the  body,  and  yet  holds  a  correlation  with  other  organs  in  getting  rid 
of  an  excess  of  those  liquids.  In  general  it  is  thickest  on  the  most  ex- 
posed parts — on  the  back  of  the  trunk,  outer  part  of  the  limbs,  palms  of 
the  hands  and  soles  of  the  feet.  It  is  thinnest  on  the  eyelids,  lips,  inner 
surface  of  the  prepuce,  and  glans  penis.  It  is  flexible,  moderately  ex- 
tensible, slightly  elastic,  semitransparent,  and  varies  in  color  in  different 
races  and  individuals.  On  the  palms  and  soles  it  is  closely  covered  with 

1  Tractus  spiralis  foraminulosus. 

2  Cutis;  derma;  deris;  corium;  pellis;  integumentum  commune. 
8  Organon  tactus. 


THE   ORGANS   OF   SPECIAL   SENSE.  629 

fine  parallel  ridges,  mostly  arranged  in  curving  lines,  and  with  peculiar 
regularity.  In  other  positions  it  presents  fine  reticular  furrows,  and  pits 
from  which  hairs  project.  In  parts  exposed  to  frequent  doubling  or 
flexion  it  becomes  more  or  less  coarsely  furrowed  or  wrinkled,  as  around 
many  of  the  joints,  and  on  the  forehead. 

The  skin  is  composed  of  two  principal  layers,  the  dermis  and  epider- 
mis ;  is  provided  with  two  kinds  of  glands,  the  sweat  and  sebaceous 
glands ;  and  is  furnished  with  two  varieties  of  appendages,  the  hairs  and 
nails. 

THE  DERMIS. 

The  Dermis1  constitutes  the  deeper  layer  of  the  skin,  and  is  thickest 
where  the  entire  skin  presents  that  condition.  It  is  about  one-sixth 
of  a  line  thick  on  the  eyelids,  from  one-fourth  to  one-half  a  line  on 
the  front  of  the  body,  and  from  one-half  a  line  to  one  and  a  half  lines 
on  the  back  of  the  body  and  the  heels.  It  is  thinner  in  the  female  than 
the  male ;  in  children,  is  about  half  as  thick  as  it  is  in  adult  age,  and  it 
becomes  thinner  in  old  age.  It  is  of  a  pinkish  cream  color,  and  varies 
in  the  depth  of  pinkish  hue  in  different  positions  according  to  its  degree 
of  vascularity. 

The  dermis  is  mainly  composed  of  a  dense  intertexture  of  bundles  of 
fibrous  tissue,  which  cross  one  another  at  acute  angles,  in  different  direc- 
tions. It  is  mingled  with  some  elastic  tissue,  which  is  most  abundant 
on  the  front  of  the  body  and  about  the  joints.  It  also  contains  unstri- 
ated  muscular  fibres,  which  descend  from  the  more  superficial  part  of 
the  dermis  to  the  bottom  of  the  hair  follicles.  When  excited  to  con- 
traction, through  the  impression  of  cold,  the  emotion  of  fear,  or  the 
influence  of  electricity,  these  muscular  fibres  elevate  the  hairs  and  pro- 
duce the  phenomenon  of  " goose  flesh."2 

The  dermis  is  densest  approaching  its  exterior  surface,  which  is  de- 
fined by  a  more  homogeneous  layer  or  basement  membrane.  Its  in- 
terior surface  is  continuous  with  the  connective  tissue  of  the  adipose 
layer  of  the  superficial  fascia,  or  in  positions  in  which  the  adipose  layer 
is  absent  it  adheres  to  the  deeper  layer  of  the  superficial  fascia,  or  other 
subjacent  structure,  by  more  or  less  long  and  loose  connective  tissue, 
which  allows  the  skin  to  be  moved  backward  and  forward.  The  interior 
surface,  when  freed  from  its  connections,  presents  the  appearance  of  a 
coarsely-corded  net,  with  the  meshes  occupied  by  small,  round  masses  of 
adipose  tissue. 

The  outer  surface  of  the  dermis  is  provided  with  a  multitude  of  mi- 

1  Derma;  derm;  cutis;  cutis  vera;  corium;  true  skin.  2  Cutis  anserina. 


030 


THE   ORGANS   OF   SPECIAL   SENSE. 


FIG.  379. 


nute  processes,  which,  from  their  function,  have  been  named  the  tactile 
papillae.1    They  vary  in  number  and  degree  of  development  in  different 

parts  of  the  body.  They  are  most 
numerous  and  longest  on  the  palms 
and -soles,  where  they  are  arranged 
in  double  rows  supported  on  linear 
ridges  of  the  dermis.  corresponding 
with  those  seen  on  the  surface  of 
the  skin.  They  are  also  numerous 
on  the  prepuce,  glans  penis,  nym- 
phae,  clitoris,  and  nipple.  In  other 
positions  they  are  more  widely  set 
apart,  less  well  developed,  and  on 
the  face  are  nearly  obsolete. 

The  largest  or  .best  developed 
papillae  are  conical,  and  either  sim- 
ple or  compound — the  latter  con- 
sisting of  two,  three,  or  even 
more,  springing  from  a  common 
base.  The  less  well  developed  pa- 
pillre  are  mammillary  or  wart  like, 
and  degenerate  into  feeble  ridges 
of  the  surface.  In  the  palms  and 
soles  they  measure  from  the  one- 
thirtieth  to  the  one-tenth  of  a  line 
long,  and  in  other  positions  descend 
from  the  one-thirtieth  to  one-eight- 
ieth of  a  line  They  are  composed 
of  a  continuation  of  the  fibrous 
structure  of  the  dermis,  defined 
by  structureless  basement  mem- 
brane, and  receive  terminal  filaments  of  the  cutaneous  nerves,  and  each 
a  looped  capillary  blood-vessel.  Some  of  the  papillae  of  the  palm  and 
sole  contain  peculiar  bodies,  which  have  already  been  described  as  tactile 
corpuscles  on  page  511. 

The  dermis  is  richly  supplied  with  blood-vessels,  lymphatics,  and 
nerves.  The  arteries  of  the  skin  penetrate  from  beneath,  and  end  in  a 
capillary  net-work,  which  becomes  more  close  the  nearer  it  approaches 
the  exterior  surface  of  the  dermis,  and  from  this  net-work  single  loops 
enter  the  tactile  papillae.  The  veins  emerging  from  the  skin  are  more 


VERTICAL  SECTION  OF  THE  eKi\  OF  THE  FORE- 
FINGER ACROSS  TWO  OF  THE  RIDGES  OF  THE  SUR- 
FACE, highly  magnified.  1,  dermis  composed  of 
an  intertexture  of  bundles  of  fibrous  tissue;  2,  epi- 
dermis; 3,  its  cuticle;  4,  its  soft  layer;  5,  subcu- 
taneous connective  and  adipose  tissue:  6,  tactile 
papillae;  7.  sweat  glands;  8,  duct;  9,  spiral  pas- 
sage from  the  latter  through  the  epidermis;  10, 
termination  of  the  passage  on  the  summit  of 


tactus;  papillae  of  touch;  papillary  layer  of  the  derm;  corpus  papillare. 


THE   ORGANS   OF   SPECIAL   SENSE.  631 

numerous  and  much  larger  than  the  arteries,  and  end  in  the  superficial 
venous  trunks  beneath.  The  lymphatics  also  form  an  intricate  net-work 
in  the  dermis,  and  are  most  numerous  on  the  fore  and  inner  part  of  the 
body  and  limbs,  especially  in  the  palms  and  soles.  The  nerves  are 
abundant,  and  are  derived  from  the  various  cutaneous  branches  described 
in  the  account  of  the  nervous  system.  They  extend  to  the  exterior  sur- 
face of  the  dermis,  and  into  the  tactile  papillae ;  but  their  mode  of  term* 
ination  has  not  been  accurately  ascertained. 

By  boiling,  the  dermis  is  resolved  into  gelatin,  and  indeed  the  main 
source  of  glue  used  in  the  arts  is  obtained  from  fragments  of  the  skin 
of  animals.  By  tanning,  the  dermis  is  converted  into  leather;  deprived 
of  fatty  and  other  matters,  and  properly  thinned,  it  forms  parchment. 
The  cut  edge  and  rough  surface  of  a  piece  of  leather  illustrates  the 
arrangement  of  the  fibrous  structure  of  the  dermis,  and  its  smooth  outer 
surface  frequently  exhibits  the  mouths  of  the  hair  follicles,  papilla,  and 
other  marks. 

THE  EPIDERMIS. 

The  Epider'mis1  constitutes  the  superficial  layer  of  the  skin,  and 
holds  the  same  relation  to  the  dermis  that  the  epithelium  does  to  the 
deeper  layer  of  the  mucous  membranes.  It  is  thickest  in  the  palms 
and  soles,  where  it  measures  from  the  one-tenth  to  one  line  or  more,  and 
in  other  positions  forms  a  thin  layer  ranging  from  about  ^  to  T!ff  of  a 
line.  The  thickness  is  however  in  some  measure  dependent  on  the  pres- 
sure or  friction  to  which  the  skin  is  subjected,  and  thus  it  becomes 
thicker  in  the  palm  of  the  laborer  and  the  sole  of  the  plowman  than  in 
most  other  persons.  Corns  are  much-thickened  portions  of  the  epider- 
mis in  particular  spots,  which  are  exposed  to  excessive  pressure  or 
friction.  They  are  not  necessarily  confined  to  the  feet,  but  are  produced 
on  the  knee  of  the  shoemaker  from  frequent  hammering,  or  in  front  of 
the  clavicle  of  the  soldier  from  the  pressure  of  his  musket.  The  pain  so 
frequently  induced  by  their  presence  is  due  to  their  exciting  inflammation 
in  the  sensitive  dermis  upon  which  they  press,  just  as  a  pebble  does  under 
the  same  circumstances. 

The  epidermis  is  entirely  non-vascular,  but  derives  its  nutritive  liquid 
by  imbibition  from  the  vessels  of  the  dermis.  It  is  without  nerves,  and 
therefore  completely  insensible;  but  it  transmits  impressions  through 
pressure  to  the  exquisitely  sensitive  dermis,  the  soft  and  delicate  struc- 

1  Cuticnla;  cuticle;  epiderma;  epichorium ;  cutis  extima;  pellis  summa;  lamina 
prima  cutis;  scarf  skin. 


632 


THE   ORGANS   OF   SPECIAL   SENSE. 


ture  of  which  it  protects  from  laceration  or  drying.  If  removed,  the 
contact  of  the  atmosphere  is  sufficient  to  produce  inflammation  of  the 
dermis,  and  after  death  the  latter  speedily  dries. 

The  epidermis  consists  of  two  layers,  quite  different  in  many  respects ; 

one  being  named  the  cuticle,  the  other  the  soft  epidermic  layer. 

% 

%  The  Cu'ticle1  is  a  nearly  dry,  yellowish,  translucent,  horn-like  mem- 
brane, well  illustrated  by  the  slice  of  a  corn.  Its  deeper  surface  is  con- 
tinuous with  the  soft  epidermic  layer  from  which  it  is  incessantly  renewed, 
while  from  its  free  surface  it  is  constantly  worn  away,  or  is  shed  in  small 
flakes,  constituting  the  so-called  scurf  and  dandruff.  In  many  lower 
animals,  as  for  instance  serpents,  it  exfoliates  from  time  to  time  in  an 


FIG.  380. 


FIG.  381. 


SCURF  FROM  THE  LEG.  1,  a  fragment  of  scurf, 
consisting  of  dried,  flattened,  non-nucleated  cells 
or  scales;  2,  a  few  cells  with  a  nucleus;  3,  a  cell 
more  highly  magnified,  to  exhibit  its  polyhedral 
form. 


FRAGMENT  OF  DANDRUFF  FROM  THE  HEAD.    1,  por- 
tion of  dandruff,  consisting  of  non-nucleated  cells ; 

2,  several  fragments,  consisting  of  nucleated  cells; 

3,  isolated  cells,  some  with  and  without  nuclei :  4. 
a  cell  more  highly  magnified,  exhibiting  granular 
contents  and  a  nucleus. 


entire  state.  It  consists  of  numerous  laminae,  according  to  its  degree  of 
thickness,  of  minute  scales,  which  are  completely  flattened  and  nearly 
dried  organic  cells.  These  have  a  small  quantity  of  granular  contents, 
but  usually  no  nucleus,  though  frequently  the  remains  of  one,  especially 
in  the  deeper  part  of  the  cuticle,  may  be  detected. 

By  treatment  with  a  solution  of  potash,  the  scales  of  the  cuticle  sep- 
arate from  one  another,  and  swell  into  spheroidal  vesicles.  Hence  it  is 
that  alkaline  solutions  remove  the  epidermis.  A  blister  or  burn  pro- 
duces inflammation  of  the  dermis  and  effusion  of  liquid,  which  breaks  up 
the  soft  epidermic  layer,  and  elevates  the  cuticle. 

By  maceration  of  the  skin  after  death,  the  cuticle  becomes  detached 
from  the  dermis  through  disorganization  of  the  soft  epidermic  layer. 
When  the  cuticle  is  sufficiently  thick  and  strong  to  sustain  itself,  it  may 
be  removed  in  large  pieces,  and  thus  from  the  hand  it  may  be  stripped 
off  like  a  glove. 


Cuticula. 


THE   ORGANS   OF   SPECIAL   SENSE.  633 

The  Soft'  epidermic  layer1  consists  of  many  laminae  of  delicate  poly- 
hedral cells  with  soft  granular  contents  and  a  nucleus.  The  upper 
laminae  of  cells  are  successively  more  and  more  flattened,  and  are  inces- 
santly transformed  into  the  comparatively  dry  scales  of  the  cuticle,  while 
they  are  as  constantly  reproduced  from  the  surface  of  the  dermis. 

In  the  white  race  the  soft  epidermic  layer  is  colorless,  and,Tike  the 
cuticle,  translucent,  and  hence  it  allows  the  color  and  vascularity  of  thP 
dermis  to  be  seen.  In  the  negro,  its  cells,  especially  the  deeper  ones,  are 
filled  with  brown  or  black  pigmentary  matter,  which  produces  the  char- 
acteristic color  of  the  race.  Smaller  quantities  of  the  same  material 
give  rise  to  the  various  shades  of  complexion  of  other  races,  of  different 
individuals,  and  even  different  parts  of  the  skin  of  the  same  person.  The 
sun-burnt  complexion  is  due  to  the  development  or  increase  of  the  same 
coloring  matter;  and  in  freckles  it  is  accumulated  in  spots.  As  the  soft 
epidermic  layer  Js  transformed  into  the  cuticle,  the  pigmentary  matter 
disappears  from  its  cells. 

THE  SWEAT  GLANDS. 

The  Sweat  or  perspiratory  glands2  exist  almost  everywhere  in  the 
skin,  and  number  a  million  or  more.  They  are  yellowish-red,  spheroidal 
bodies,  averaging  about  one-sixth  of  a  line  in  diameter,  and  are  lodged 
in  interspaces  of  the  deep  part  of  the  dermis,  usually  surrounded  by 
adipose  tissue.  Each  gland  consists  of  a  tube  convoluted  into  a  ball, 
and  afterwards  ascending,  as  the  sweat  duct,  in  a  slightly  tortuous  man- 
ner, to  the  exterior  surface  of  the  dermis.  The  tube  is  composed  of  an 
exterior  fibrous  layer,  succeeded  by  one  of  basement  membrane ;  and  is 
lined  with  a  pavement  epithelium,  consisting  of  polyhedral  cells  contain- 
ing a  nucleus,  and  granular  contents  mingled  with  some  yellowish  pig- 
ment particles. 

From  th>e  sweat  duct  opening  on  the  surface  of  the  dermis  a  passage 
way  conducts  to  the  exterior  of  the  epidermis.  When  the  latter  is  thin, 
the  passage  is  straight ;  but  when  thick,  as  in  the  palms  and  soles,  it 
pursues  a  spiral  course,  and  terminates  in  a  funnel-shaped  orifice.  The 
apertures  of  the  ducts  are  distinctly  visible  with  a  common  pocket  lens,  in 

1  Rete  mucosnm ;    r.  Malpighi ;    cor-  2  Glandulae  sudoripara)  :   g.  miliariae  ; 

pus,  or  stratum  Malpighi;  corpus  mu-  g.  hydrophora} ;  organa  sudoripara;  su- 

cosum ;    c.   reticulare ;    reticulum   cuta-  doriparous  glands ;  diapnogenous  appa- 

neum;  r.  mucosura;  mesodermum  ;   mu-  ratus;  perspiratory  organs;  fontes   su- 

cous  web  ;  tunica  albida  superficialis  et  doris. 
profunda,    et    gemmula,    et    bourgeons 
sanguins. 


634  THE   ORGANS  OF   SPECIAL   SENSE. 

a  single  row  on  the  summits  of  the  ridges  of  the  palms  and  soles ;  but 
in  other  positions  are  not  so  readily  distinguished. 

A  modification  of  the  sweat  glands  constitutes  the  ceruminous  glands, 
described  in  the  account  of  the  ear,  and  the  odoriferous  glands  of  the 
axilla.1  These  form  a  patch,  an  inch  and  a  half  or  more  in  diameter, 
situated  in  the  subcutaneous  connective  and  adipose  tissue  of  the  hairy 
T>art  of  the  armpit.  They  are  largest  near  the  centre  of  the  patch,  and 
gradually  diminish  toward  the  circumference,  where  they  merge  into  the 
ordinary  sweat  glands.  They  are  usually  much  better  developed  in  the 
negro,  in  whom  the  largest  reach  the  size  of  a  small  pea.  They  are  of 
a  dusky,  yellowish-red  color,  and,  like  the  sweat  glands,  are  composed  of 
a  tube  coiled  into  a  ball,  from  which  the  tube  continues  as  the  duct  to 
open  on  the  exterior  surface  of  the  skin.  The  tube  of  the  gland  con- 
tains unstriated  muscular  fibres  in  its  wall ;  and  its  cavity  is  filled  with 
a  finely  granular  matter  mingled  with  brown  or  yellow  pigment  and 
fat  particles.  Besides  an  abundance  of  sweat,  these  glands  yield  a 
strongly  odorous  substance,  which  is  somewhat  peculiar  in  the  different 
races. 

Sweat2  is  a  clear,  watery  liquid,  with  an  acid  reaction  and  a  saline 
taste.  It  contains  formic,  butyric,  and  acetic  acids,  and  a  number  of 
salts,  of  which  the  most  abundant  is  chloride  of  sodium. 

THE  SEBACEOUS  GLANDS. 

The  Seba'ceous  glands3  of  the  skin  are  very  numerous,  and  exist 
almost  everywhere,  except  in  the  palms  and  soles.  They  are  mostly 
associated  with  the  hair  follicles,  being  situated  around  them  in  groups 
from  two  to  eight  for  each  follicle,  imbedded  in  the  more  superficial  part 
of  the  dermis.  Generally  the  largest  glands  are  found  with  the  small- 
est hair  follicles,  so  that  these  appear  of  secondary  importance,  while 
the  smallest  glands  exist  in  pairs  in  connection  with  the  hairs  of  the 
scalp. 

The  largest  sebaceous  glands  are  those  of  the  nose,  concha  of  the  ear, 
skin  of  the  penis,  the  scrotum,  labia,  and  areola  surrounding  the  female 
nipple.  The  groups  of  glands  connected  with  each  hair  follicle  appear 
as  rounded  whitish  bodies  imbedded  in  the  semitransparent  skin,  and 
measure  from  one-tenth  to  one-half  a  line  or  more  in  diameter. 

1  Glandulae  odoriferae  of  Homer.  sebiferse1;  cryptae  sebacese;  folliculi  se- 

2  Sudor;    perspiration;    perspiratory  baceae:     sebiparous,    or    sebiferous 
fluid.  glands;  sebaceous  follicles,   or  crypts; 

3  Glandulae  sebaceae  ;  g.  sebiparae  ;  g.  miliary  glands ;  oil  glands. 


THE   ORGANS   OF   SPECIAL  SENSE. 


635 


The  sebaceous  glands  are  simple  or  compound,  being  composed  of 
one  or  more  purse-shaped  pouches,  the  ducts  of  which  open  into  the 


FIG.  382. 


FIG.  383. 


SEBACEOUS  GLANDS  OPENING  INTO  THE  MOUTH  OF  A 
HAIR  FOLLICLE,  much  magnified. 

mouths  of  the  hair  follicles,  or  in  the 
case  of  the  largest  glands,  together 
with  the  latter  they  open  on  the  sur- 
face of  the  skin.  In  structure  the 
glands  possess  a  delicate  wall  of 
fibrous  tissue,  defined  by  a  base- 
ment membrane,  and  are  lined  with 
an  epithelium  consisting  of  polyhe- 
dral, nucleated  cells  with  granular 
contents.  The  cavity  of  the  glands 
is  filled  with  sebaceous  matter,1 
consisting  of  cells  and  oil  globules. 
Of  the  cells,  some  contain  finely 

granular  matter   mingled  with  oil  drops,  while   others  are  distended 
with  oil. 

The  sebaceous  matter  anoints  the  hairs  with  oil  in  their  progress  of 
growth  from  the  skin,  and  also  imbues  the  cuticle,  by  which  it  is  rendered 
repellant  of  water.  The  greasiness  of  the  surface  of  the  skin,  occa- 
sioned by  this  material,  permits  the  ready  adhesion  of  dust  and  dirt,  and 
renders  the  employment  of  soaps  necessary  for  easy  removal  of  its  excess. 
The  too  free  use  of  alkaline  washes,  by  depriving  the  cuticle  of  its  oil, 
produces  a  dry  and  harsh  feeling  in  the  skin.  The  sebaceous  matter 
often  becomes  inspissated  and  distends  the  glands,  most  frequently  in  the 
face,  and  especially  on  the  nose ;  and  at  the  mouths  of  the  ducts  it 


A  LARGE  SEBACEOUS  GLAND  FROM  THE  NOSE,  viewed 

by  transmitted  light,  and  highly  magnified,  a, 
epithelium  of  the  gland ;  6,  the  same  continuous 
with  the  epidermis;  c,  the  sebaceous  matter;  d, 
subdivisions  of  the  gland ;  e,  a  hair  follicle ;  /,  a 
hair. 


Sebum,  or  sraegnia  cutaneum. 


636 


THE  ORGANS   OF   SPECIAL   SENSE. 


becomes  incorporated  with  dirt.     By  pressure  it  is  squeezed  out,  and 
from  its  assuming  the  form  of  the  duct,  is  vulgarly  taken  for  a  worm,  of 


FIG.  384. 


FIG.  385. 


Fig.  384.— SEBACEOUS  MATTER,  FROM  ONE  OF  THE  SEBACEOUS  GLANDS  OF  -HE  NOSE,  magnified.  1,  cells  filled 
with  granular  matter ;  2,  one  of  the  cells  more  highly  magnified;  3,  oil  drops  mingled  with  the  cells. 

Fig.  385. — STRUCTURE  OF  THE  SEBACEOUS  GLANDS.  A,  a  simple  sebaceous  gland,  or  one  of  the  divisions 
of  a  compound  gland,  highly  magnified,  a,  epithelial  cells;  6,  sebaceous  matter.  B,  sebaceous  cells, 
much  more  highly  magnified,  a,  small  cells  from  the  epithelial  layer ;  b,  larger  cells  abounding  in  fat;  c, 
cell  in  which  the  fat  has  accumulated  in  large  drops;  d,  cell  distended  with  fat;  e,f,  cells  from  which  the 
fat  has  partially  escaped. 

which  the  dirt  at  the  end  is  supposed  to  be  the  head.  The  sebaceous 
matter,  nevertheless,  even  in  most  healthy  individuals,  contains  a  curious 
parasitic  animal,  the  pimple  mite.1 


THE  HAIRS. 

The  Hairs2  are  solid,  thread-like  appendages  of  the  skin,  projecting 
from  almost  every  part  of  its  surface  except  the  palms  and  soles.  They 
are  flexible,  elastic,  and  shining,  but  vary  in  degree  of  development, 
fineness,  color,  form,  and  arrangement  in  different  races,  sexes,  individ- 
uals, and  parts  of  the  body.  From  the  long  hairs  of  the  head3  they 
exist  of  every  gradation  of  size  to  such4  as  are  hardly  visible. 

The  portion  of  a  hair  projecting  from  the  skin  is  its  shaft  or  stem5 
terminated  by  the  point  or  end ;  the  portion  inserted  into  the  skin  is 
the  root,6  which  begins  in  a  club-like  expansion,  named  the  bulb.7 

The  hairs  generally  project  obliquely  from  the  skin,  singly,  or  in 
groups  of  two,  three,  or  more.  They  are  regularly  arranged  in  the  dif- 
ferent parts  of  the  body,  mostly  in  curving  lines  or  whorls  from  particu- 
lar points. 


1  Acarus  folliculorum ;  Demodex  folliculorum. 
2Pili;  the  hair;  crinis;  pile;  thrix. 

3  Capilli. 

4  Lanugo ;  down. 


5  Scapus. 

e  Radix  pili. 

7  Bulbus  pili;  button. 


THE  ORGANS  OF   SPECIAL  SENSE. 


637 


The  fine  silken  hair  of  the  head  of  the  white  race  is  cylindrical ;  the 
crisp,  curling  hair  of  the  beard,  other  parts  of  the  body,  and  the  head 
of  the  negro,  is  more  or  less  flattened  cylindrical. 

In  structure  the  hairs  consist  of  an  exterior  cuticle,  a  cortical  sub- 
stance, and  an  interior  medullary  substance. 

FIG.  386. 

A  ^v   .# 


FIG.  387. 


A.  PORTION  OF  THE  SHAFT  OF  A  LIGHT  HAIR,  mag- 
nified. The  longitudinal  lines  are  produced  by 
the  cortical  substance;  the  transverse,  undulating  lines,  by  the  cuticle.  B.  Isolated  scales  of  the  cuticle. 

The  cuticle  of  the  hair  consists  of  a  single  layer  of  thin,  colorless, 
quadrilateral  scales  or  completely  flattened  cells,  which  overlap  like  the 
shingles  of  a  roof.  The  projecting  edges  of 
these  scales  are  directed  upward  and  outward 
along  the  shaft;  and  in  a  hair  examined  be- 
neath the  microscope  are  seen  as  irregularly 
undulating  and  intersecting  transverse  lines. 
As  feebly  as  their  edges  appear  to  project, 
they  nevertheless  present  an  obstacle  to  the 
hair  being  moved  in  any  other  direction  than 
with  its  root  forward,  when  rubbed  between 
two  surfaces.  It  is  upon  a  similar  condition 
that  the  felting  of  the  hair  and  wool  of  various 
animals  depends. 


The  cortical  substance1  makes  the  chief  bulk 
of  the  hair,  and  is  that  upon  which  the  color 
mainly  depends  in  different  races  and  individuals. 
When  sufficiently  translucent,  as  in  white  or 
light-colored  hairs,  beneath  the  microscope  it 
presents  a  longitudinally  striated  appearance. 
It  is  composed  of  layers  of  flexible  fibres,  into 
which  it  is  not  unfrequently  found  more  or  less 
split  at  the  ends  of  hairs,  as  the  result  of  dry- 
ing and  friction.  The  fibres  consist  of  much 
elongated,  fusiform  cells  containing  a  linear 
nucleus.  The  coloring  matter  is  usually  dif- 


itil 


PORTION  OF  A  HAIR  FROM  THE 
OUTER  PART  OF  THE  THIGH,  magni- 
fied. 1,  shaft  of  the  hair  covered 
with  transverse  markings  indicat- 
ing the  projecting  edges  of  the  cu- 
ticular  scales ;  2,  cortical  substance 
at  the  end  of  the  hair  broken  up 
into  coarse  fibres  as  the  result  of 
friction  of  the  clothing. 


1  Cortex. 


638  THE   ORGANS  OF   SPECIAL   SEXSE. 

fused  through  the  cortical  substance,  though  it  is  also  often  accumulated 
in  streaks  or  spots.  With  the  loss  of  the  coloring  matter,  generally 
occurring  in  the  advance  of  age,  the  cortical  substance  becomes  white. 

The  medullary  substance1  is  frequently  absent,  especially  in  dark- 
colored  hairs  of  the  head,  and  in  fine  down-like  hairs  of  the  body.  It 
occupies  the  axis  of  the  hair,  and  by  transmitted  light  appears  as  a  dark, 
coarsely  granular  streak,  usually  of  uniform  diameter,  but  often  con- 
tracted, and  sometimes  completely  interrupted  in  its  course.  By  re- 
flected light  it  appears  white,  though  modified  by  the  color  of  the  cortical 
substance  through  which  it  is  seen.  It  consists  of  somewhat  cuboidal 
cells,  with  granular  contents  and  an  indistinct  nucleus. 

The  medullary  substance  is  generally  mingled  with  more  or  less  air, 
in  small  bubbles,  which  penetrates  from  the  ends  of  the  hairs,  and  gives 
to  these  when  white  the  characteristic  silvery  lustre. 

The  root  of  the  hair  is  lodged  in  a  flask-shaped  receptacle  of  the  skin 
called  the  hair  follicle,2  at  the  bottom  of  which  is  a  papilla  from  which 
the  hair  grows.  The  hair  follicles  are  imbedded  in  the  derails,  or,  in  the 
case  of  the  large  hairs,  extend  into  the  subcutaneous  connective  and 
adipose  tissue.  They  may  be  viewed  as  inflections  of  the  skin,  and  the 
hair  papilla  at  their  bottom  as  a  modified  tactile  papilla. 

The  wall  of  the  hair  follicle  is  composed  of  a  fibrous  layer  defined  by 
a  basement  membrane,  and  lined  with  an  inflection3  of  the  epidermis. 
The  cuticular  portion4  of  this  inflection  is  remarkably  modified  from  the 
corresponding  layer  on  the  free  surface  of  the  skin.  It  forms  a  com- 
paratively thick,  transparent,  elastic  membrane,  composed  of  somewhat 
elongated  non-nucleated  cells,  adhering  to  one  another  in  such  a  manner 
as  to  assume  the  appearance  of  fenestrated  membrane.  The  elastic 
cuticular  layer  merges  into  the  softer  epidermic  layer  beneath,  and 
tightly  clasps  the  root  of  the  hair.  It  perhaps  acts  upon  the  latter  as 
it  is  projected  in  its  growth  from  the  papilla,  as  a  wire  is  acted  upon 
when  it  is  protruded  through  a  draw-plate. 

The  hair  papilla5  is  ovoid,  of  soft  consistence,  and  supplied  with  both 
capillary  vessels  and  nerves.  The  hair  bulb  caps  or  incloses  the  papilla, 

1  Medulla.  4  Inner  root  sheath  of  the  hair.     The 

2  Folliculus  pili.  softer  cells  beneath  constitute  the  outer 

3  Root  sheath  of  the  hair;  vagina  pili.       root  sheath. 

5  Papilla  pili ;  pulpa,  or  blastema  pili. 


THE   ORGANS   OF   SPECIAL   SENSE. 


639 


and  in  the  extraction  of  a  hair  it  is  traction  on  the  latter  which  gives 

rise  to  the  pain. 

The  root  of  the  hair  is  softer  and  thicker  than  the  shaft,  the  character 

of  which  it  assumes  in  its  growth.     The  hair  bulb  is  soft,  translucent, 

and  is  continuous  at  the  bottom  of  the  hair  papilla  with  the  epidermic 

layer  of  the  hair  follicle.  It  is  com- 
posed of  soft,  polyhedral  nucleated 
cells,  which  exhibit  a  gradual  and 
successive  transition  into  the  cu- 
ticle, cortical  and  medullary  sub- 
stances of  the  root  above.  By  the 

FIG  380. 


FIG.  388. 


-4- 


Fig.  388.  ROOT  OF  A  HAIR  LODGED  WITHIN  ITS  FOLLICLE,  magnified,  a,  shaft  of  the  hair;  b,  root;  c,  bulb : 
d, cuticle  of  the  hair;  e,f,  epidermic  lining  of  the  follicle;  g,  basement  membrane;  h,  fibrous  layer  of 
the  wall  of  the  hair  follicle;  i,  hair  papilla;  k,  mouths  of  two  sebaceous  glands;  I,  derrnis;  m,  soft  layer 
of  the  epidermis;  n,  cuticle  of  the  epidermis. 

Fig.  389.  DIAGRAM  OF  STRUCTURE  OF  THE  ROOT  OF  A  HAIR  WITHIN  ITS  FOLLICLE.  1,  hair  papilla;  2,  capil- 
lary vessel;  3,  nerve  fibres;  4,  fibrous  wall  of  the  hair  follicle;  5,  basement  membrane;  6,  soft  epider- 
mic lining  of  the  follicle;  7,  its  elastic  cuticular  layer;  8,  cuticle  of  the  hair;  9,  cortical  substance; 
10,  medullary  substance;  11,  bulb  of  the  hair  composed  of  soft  polyhedral  cells;  12,  transition  of  the  lat- 
ter into  the  cortical  substance,  medullary  substance,  and  cuticle  of  the  hair. 

transformation  of  the  cells  into  the  elements  just  mentioned,  and  the  pro- 
duction of  new  cells  from  the  papilla,  the  hair  constantly  grows  in  length. 
Like  the  epidermis  the  hairs  receive  nutriment  by  imbibition  —  the 
liquids  being  transmitted  from  one  cell  element  to  another  in  gradually 
diminishing  quantity  throughout  the  length  of  the  hair. 


640  THE   ORGANS   OF   SPECIAL   SENSE. 

The  hairs  are  not  only  renewed  by  constant  growth,  but  in  many  in- 
stances, even  in  the  healthy  condition,  but  especially  after  diseases,  they 
are  cast  off  or  shed,  and  new  ones  are  produced.  In  such  instances, 
likewise  when  the  hairs  are  violently  extracted,  the  new  hairs  are  pro- 
duced from  the  same  hair  follicles,  but  sometimes  at  least  from  new  pa- 
pillae. Permanent  baldness,  so  often  occurring  in  the  advance  of  age, 
arises  from  atrophy  of  the  hair  papillae. 

The  apparent  growth  of  the  beard  after  death  arises  from  the  shrink- 
ing of  the  skin,  which  protrudes  the  remaining  roots  of  the  hairs  the 
eighth  of  an  inch  or  more. 

THE  NAILS. 

The  Nails1  are  corneous  appendages  of  the  skin,  and  correspond  with 
the  claws  and  hoofs  of  other  animals.  They  are  thin,  flexible,  translu- 

FIG.  390.  FIG.  391.  FIG.  392. 


Fig.  390.  MATRIX  OF  THE  NAIL.  1,  fold  of  the  skin  which  covers  the  root  of  the  nail ;  2,  the  fold  par- 
tially turned  up  to  show  the  depth  of  the  groove  beneath ;  3,  4,  posterior  and  anterior  portions  of  the 
matrix,  the  former  the  less  vascular,  and  giving  rise  to  the  appearance  called  the  lunula.  The  longitudi- 
nal lines  indicate  the  ridges  bordered  with  papilla;. 

Fig.  391.  UNDER  SURFACE  OF  THE  NAIL.  1,  root;  2,  part  corresponding  with  the  lunula;  3,  grooved  sur- 
face adapted  to  the  ridges  of  the  matrix ;  4,  free  border. 

Fig.  392.  VERTICAL  SECTION  OF  THE  END  OF  A  FINGER.  1,  epidermis  on  the  back  of  the  finger;  2,  point  at 
which  it  is  reflected  to  become  continuous  with  the  nail;  3,  the  nail;  4,  epidermis  at  the  end  of  the  fin- 
ger; 5,  6,  7,  8,  surface  of  the  dermis  corresponding  with  the  position  of  the  soft  epidermic  layer;  9, 10, 
11,  12,  dermis;  13,  last  phalanx;  14,  flexor  tendon. 

cent,  quadrilateral  plates  continuous  with  the  epidermis,  and  resting  on 
a  depressed  surface  of  the  dermis,  called  the  matrix  or  bed. 

The  exposed  portion  of  the  nail,  named  its  body,  is  terminated  ante- 
riorly by  the  free  border.  The  posterior  third  or  fourth  of  the  nail, 
named  its  root,  is  lodged  in  a  deep  groove2  of  the  matrix,  and  the  lateral 
borders  are  received  into  shallow  grooves.  From  the  body  of  the  nail 
the  root  gradually  thins  away  to  a  sharp  edge,  and  the  lateral  borders 
more  abruptly  thin  out. 

1  Ungues.  2  Vallecula  unguis ;  nail  follicle. 


THE  ORGANS   OF   SPECIAL   SENSE. 

The  translucency  of  the  nail  permits  the  redness  of  the  matrix  to  be 
seen,  which  color  is  due  to  vascularity  of  the  part.  The  less  degree  of 
vascularity  of  the  matrix  at  the  root,  defined  by  a  semicircular  line,  gives 
rise  to  the  whitish  spot  called  the  lu'nula.1  The  free  surface  of  the  body 
of  the  nail  is  shining  and  faintly  striated  longitudinally ;  its  under  sur- 
face is  finely  grooved  in  the  same  direction. 

The  matrix  of  the  nail,  constituted  by  a  highly  vascular  portion  of  the 
dermis,  is  covered  with  fine  longitudinal  ridges  beset  with  a  multitude  of 
minute  papillae.  The  ridges  and  papillaa  fit  into  the  grooves  of  the 
under  surface  of  the  nail,  and  correspond  with  the  tactile  papillae  in 
other  positions. 

By  maceration  the  nails  become  detached  continuously  with  the  epi- 
dermis from  the  dermis.  They  consist  of  a  thick  horny  layer  attached 
by  a  delicate  soft  layer  to  the  dermis. 

The  horny  layer  answers  to  the  cuticle  of  the  epidermis,  and  is  com- 
posed of  numerous  intimately  associated  laminae  of  flattened  nucleated 
cells  or  scales,  which  can  only  be  distinguished  microscopically  after 
treatment  with  certain  chemical  reagents,  as  the  alkalies. 

The  soft  layer2  of  the  nails  corresponds  with  that  of  the  epidermis, 
and  like  it  is  composed  of  delicate,  polyhedral  nucleated  cells.  These 
are  incessantly  transformed  into  the  scales  of  the  horny  layer,  and  are 
renewed  from  the  surface  of  the  dermis.  By  the  constant  addition  of 
cells  at  the  root,  the  nail  grows  in  length ;  by  addition  beneath,  they 
grow  in  thickness. 

1  Semilunula;  arcus;  albedo  unguium. 

2  Stratum  Malpighi;  soft  mucous  layer;   stratum  mucosum. 

41 


INDEX. 


ABDOMEN 211 

cavity  of 298 

Abdominal  parietes 211 

ring,  external 213,  220 

internal 219 

walls 211 

Abduction 47 

Abductor  of  great  toe 257 

of  little  finger 237 

of  little  toe 258 

of  thumb 236 

Accessory  flexor  of  the  foot 256 

parotid  gland 279 

Acetabulum 124 

Acid,  butyric 29 

carbonic 29 

chloro-hydric 28 

formic 29 

lactic 29 

Acini  of  thymus  body 457 

Acromion 132 

Adduction 47 

Adductor  of  great  toe 257 

of  little  finger 237 

of  thumb 236 

great 250 

long 249 

short 250 

Adam's  apple 193,  440 

Adipose  tissue 176 

Afferent  vessels 429 

Air-cells 452 

Alar  folds 162 

Albumen 26 

Albuminose 26 

Albugineous  tunic  of  testis 470 

Alimentary  apparatus 273 

canal  273 

Allantois 463 

Alveolar  border 77,     84 

Alveoli 77 

Ammonia,  urate  of. 29 

Ampulla 623 

Anatomy 17 

Anastomoses 333 

Angle,  facial 88 


Angles  of  the  eye 595 

Ankle 152,  153,  238 

Ankle  bone 153 

joint 163 

Antihelix 613 

Antitragus 613 

Anus 318 

internal  sphincter  of. 319 

pouches  of 319 

Anvil 619 

Aorta 351 

abdominal 383 

thoracic 381 

Aortic  orifice 222 

Aperture  of  the  larynx 445 

Aponeuroses 180 

Apparatus,  lachrymal 598 

Appendages  of  the  eye 594 

Aqueous  humor 610 

Arachnoid  membrane 539 

Arch  of  aorta 351 

deep  palmar 378 

plantar 404 

superficial  palmar 380 

zygomatic 88,     89 

Arches,  palatine 276 

Arciform  fibres 531 

Arcus  senilis 604 

Areola 500 

Areolar  tissue 170 

Arm 223 

Arm  bone 132 

Armpit 228 

Arteries 332,  351 

anterior  intercostal 371 

articular 400 

bronchial 382,  4~>3 

calcanean 403 

cerebellar,  inferior 368 

common  iliac 390 

digital    of    superficial    palmar 

arch 381 

of  plantar  arch 404 

external  pudic 396 

helicine 478 

ileal 387 

(643) 


644 


INDEX. 


Arteries,  inferior  articular  

400 

Artery,  interosseous  . 

379 

intercostal  

382 

communicating  

RRO 

anterior  branches  of  

383 

coronary  

384 

dorsal  branches  of 

383 

left 

353 

interosseous   of  palmar  arch 

378 

right 

858 

ieiunal  .. 

387 

cystic  

385 

lateral  sacral  

392 

deferent  393 

473 

lumbar 

389 

dental    of  inferior  maxillary 

862 

anterior  branches  of 

389 

descendin**  palatine 

868 

389 

359 

spinal  branches  of  

389 

dorsal  lingual  

356 

mediastinal  371, 

382 

dorsal,  of  clitoris  

8% 

oesophageal 

382 

of  great  toe 

'102 

ovarian 

390 

of  penis 

895 

pancreatic                             

386 

pedal 

401 

perforating,  of  internal  inaru- 

scapular  

374 

marv... 

371 

duodenal  

387 

of  plantar  arch  

404 

epigastric  

3% 

of  profound  femoral  

397 

external  carot  id  

355 

pericardiac 

382 

iliac 

89fi 

phrenic  ... 

389 

malleolar 

401 

renal  

390 

plantar 

404 

short  gastric  

386 

facial  357, 

358 

spermat  ic  

390 

fern  oral  

306 

splenic  branches  of  splenic 

386 

frontal 

866 

superior  articular 

400 

gastro-epiploic   right 

385 

supra-renal 

390 

duodenal 

885 

tarsal          ..  .. 

401 

srluteal.  . 

393 

vesical      

393 

great  meningeal  

361 

Artery   angular  .        ... 

358 

hsjmorrhoidal,  inferior  

394 

acromial  thoracic  

373 

middle  

394 

anastomotic                            37G 

398 

superior 

888 

anterior  auricular 

360 

hepatic   .  .    . 

885 

carpal                             377 

380 

left 

386 

cerebral 

366 

right   

385 

ciliary  

365 

hyoid  branch  of  superior  thyroid 

356 

circumflex  

374 

ilio-colic  

387 

communicating  

366 

ilio-lumbar  

39? 

dental  of  infra-orbital 

36° 

inferior  coronary 

858 

ethmoidal 

365 

maxillary  .       .            

861 

interosseous 

379 

mesenteric  

388 

nasal 

366 

palatine  

358 

spinal       

368 

profound  

375 

360 

thyroid 

370 

tibial                               400 

401 

vesical                              .. 

893 

ascending  cervical 

371 

infra-  orbital 

3  (5? 

axillary 

372 

innominate..  .       

353 

basilar                         

368 

ischiatic  

895 

brachial                  374, 

376 

internal  auditory  

369 

394 

carotid 

363 

394 

circumflex                  

398 

central  retinal 

365 

iliac       

391 

choroid 

366 

401 

365 

371 

loner.... 

365 

maxillary  361, 

362 

•"  »  . 
short  

365 

plant  ar  

403 

circumflex  iliac 

396 

pudic         

393 

colic   left 

388 

380 

middle 

387 

365 

right  .  ..        

387 

laryngeal  

356 

354 

lateral  nasal    

358 

right... 

354 

lingual...                

356 

INDEX. 


645 


Artery,  long  thoracic 

medullary 

nutritious 

meningeal 

branches  of  anterior  eth- 
moidal 

branches  of  occipital 

metacarpal 

inetatarsal 

middle  articular  of  popliteal.... 

cerebral  

sacral 

temporal 

muscular  branches  of  superior 

thyroid 

musculo-phrenic 

nasal  

obturator 

occipital 

ophthalmic 364, 

pancreatico-duodenal 

palpebral 

parotid   branches    of    external 

carotid 

permeal 

peroneal  anterior 

posterior 

pharyngeal 

popliteal.. 399, 

posterior  auricular 

carpal 378, 

cerebellar  

circumflex 

communicating 

dental,  of   superior  maxil- 
lary .• 

ethmoidal 

interosseous  

scapular 

temporal 

tibial , 402, 

principal,  of  the  thumb 

profound  cervical 

femoral 

pulmonary 

left 

right 

pyloric 

radial 37G, 


373 
376 
403 

368 


recurrent, 
index... 


ranine 

recurrent  tibial.... 

sigmoid 

small  meningeal 

spheno-palatine 

spinal 

branches  of  vertebral 

splenic 

subclavian,  left 

right 

sublingual 


366 
359 
378 
402 
400 
366 
389 
360 

356 
372 
366 
392 
359 
365 
385 
366 

359 

394 
403 
403 
356 
400 
359 
380 
369 
374 
366 

362 
365 
380 
370 
360 
403 
378 
372 
397 
453 
405 
405 
385 
377 
377 
378 
356 
401 
388 
361 
363 
368 
368 
386 
367 
367 
356 


Artery,  sub-maxillary  branches  of 

facial 358 

submental 358 

subscapular 374 

superficial  circumflex 397 

epigastric 397 

superior  cerebellar 369 

cervical 370 

coronary  358 

epigastric 372 

intercostal 372 

maxillary 362 

mesenteric 386 

phrenic 371 

profound 375 

thoracic 373 

thyroid 355 

vesical 393 

stylo-mast oid 359 

supra-orbital 360,  365 

supra-scapular 370 

temporal 360 

tonsillar '. 358 

transverse  facial 360 

perineal 394 

tympanic 361 

ulnar,  and  ulnar  recurrent 379 

uterine 305 

vaginal 395 

vertebral 367,  368 

volar : 377 

Articular  borders 34 

cartilage 48,  174 

extremities 34 

process 34 

surfaces 34 

Articulation,  carpo-metacarpal 147 

crico-arytenoid 443 

crico-thyroid 442 

inferior  radio-ulnar 145 

tibio-fibular 163 

intercarpal 147 

middle  radio  uluar 145 

radio-carpal 146 

scapulo  clavicular 142 

sterno-clavicular 141 

superior  radio-ulnar 145 

tibio  fibular 163 

temporo-maxillary 86 

Articulations 46 

costo-sternal 119 

costo-vertebral 118 

immovable....  46 

intertarsal 164 

metacarpo-phalangial 147 

metatarso-phalangial 1 66 

movable 46 

of  the  atlas Ill 

axis Ill 

hip  bones 125 

lower  extremities 158 

occipital  bone Ill 


646 


INDEX. 


Articulations  of  the  ribs 118 

of  the  sternum 118 

upper  extremities 141 

vertebral  column 107 

Arytenoid  cartilages 441 

Auditory  meatus,  external 63 

internal 63 

process 63,    64 

Axis 101 

cerebro-spinal 503,  513 

coeliac 384 

fibre 505 

of  the  pelvis 127 

Aryteno-epiglottic  folds 445 

Astragalus 153 

Asperous  ridge 148 

Atlas 100 

Auricle  of  the  ear 612 

of  the  heart 343 

left 344 

right 343 

Auricular  appendage 343,  344 

Auriculo-ventricular  orifice,  left,  344,  347 

right 344,  345 

Axilla 223 

BASILAR  process 51 

Base  of  the  skull 90 

Basement  membrane 262 

Band,  semicircular 524 

Back 200,  203 

of  hand 223 

Ball  of  the  thumb 222 

Band-like  ligaments 48 

Belly 211 

cavity  of 298 

muscles  of 178 

Bile  ducts 324 

Biliary  duct,  common 328 

Biliverdin 29 

Bladder,  ligaments  of. 403 

urinary 300,  462 

Blood 338 

corpuscles 339 

colorless 340 

red 339 

liquor 340 

Bodies,  geniculate 524 

nerve  capsular 510 

olivary 530 

Pacchionian  536 

pyramidal 530 

quadrigeminal 525 

restiform 531 

striated 523 

supra-renal. 465 

Body,  ciliary 605 

dentated 528,  531 

of  bone 34 

of  teeth 285 

quadrigeminal 525 

pituitary 518 


Body,  striated 523 

thymus 456 

thyroid 455 

Bone,  occipital 50 

arm 132 

canaliculi  of. 41 

capitate 138 

collar 129 

cuboid 154 

cuneiform 137 

ethmoid 56 

frontal 58 

hip 121 

hyoid 96 

inferior  maxillary 83 

innominate 121 

lachrymal 80 

lacunae  of. 41 

lunar 137 

malar 83 

nasal 81 

palate 78 

parietal 60 

pisiform 137 

scaphoid,  of  carpus 137 

scaphoid,  of  tarsus 154 

shin 150 

sphenoid ni* 

superior  maxillary , 76 

temporal 61 

thigh 148 

trapezial 137 

trapezoid 137 

turbinated 81 

unciform 138 

vascular  canals  of.. 40 

Bones,  articular  extremities  of. 34 

articular  process  of 34 

body  of 34 

borders  of 34 

canal  of 34 

canaliculi  of. 41 

carpal 136 

compact  substance  of. 36 

condyles  of 34 

crest  of 34 

cuneiform,  of  tarsus 155 

diaphysis  of 42 

distal  extremity  of 34 

endosteum  of 39 

epiphyses  of. 42 

foramen  of 34 

fossa  of 34 

head  of 34 

irregular 34 

lacunae  of 41 

line  of 34 

long 34 

marrow  of 36 

meatus  of 34 

medulla  of 36 

medullary  cavity  of 36 


INDEX. 


647 


Bones,  metacarpal 138 

metatarsal 156 

neck  of 34 

periosteum  of 39 

process  of 34 

proximal  extremity  of 34 

ridge  of 34 

sesamoid 140,  157 

shaft  of 34 

short 34 

sinus  of 34 

spinous  process  of. 34 

spongy  substance  of 36 

surface  of 34 

tabular 34 

tubercle  of 34 

tuberosity  of 34 

vascular  canals  of 40 

Brain 503,  513,  514 

gray  substance  of 503,  505 

white  substance  of. 503,  504 

ventricles  of. 521,  523,  531 

Breasts 499 

Bromine 21 

Bronchi 448 

Bronchial  arteries 453 

tubes 453 

veins 453 

Bronchus,  left 449 

right 448 

Brunner's  glands 312 

Bulb,  olfactory 540 

Bundles  of  muscles 178 

Bursse,  synovial 183,  265 

Buttocks 238 

Butyrin 27 

CAECUM 315 

Calcaneum 154 

Calcium 21,     25 

Calyces 461 

Canal,  alimentary 273 

anterior  dental 77 

carotid 65 

infra-orbital 77 

inguinal 219 

lachrymal 599 

naso-palatine 78 

posterior  dental 77 

posterior  palatine 79 

pterygoid 56 

pterygo-palatine 56,     80 

sacral 105 

semicircular 623 

spinal 114 

Canals,  semicircular 622,  623 

vascular  of  bone 40 

Canine  teeth 287 

Capillaries 337 

Capitate  papillae 282 

Capsular  ligaments 48 

Capsule  of  the  lens 611 


Carbou 21,     25 

Carbonate  of  lime 28 

of  magnesia 28 

of  soda  28 

Carbonic  acid 29 

Cardiac  orifice  of  stomach 305 

Carneous  columns 345 

Carotid  canal 65 

Carpal  bones 136 

Carpus 136,  223 

Cartilage 171 

articular 48,  174 

ensiform 117 

Cartilages,  costal 114,  116 

of  the  larynx 440 

of  the  nose 589 

palpebral 596 

permanent 172 

temporary 172 

Cartilaginous  rings  of  bronchi 449 

Caruncle,  lachrymal 598 

Caruncles,  myrtiform 490 

Casein , 26 

Cava,  inferior 420 

superior 406 

Cavernous  bodies 476 

of  clitoris 493 

of  penis 476 

Cavities,  nasal 591 

Cavity  of  the  uterus 482 

Cell,  hepatic 326 

organic 22 

Cells,  spermatic 472 

Cellular  layer  of  membranes 259 

Cement  of  teeth 289,  291 

Centres  of  ossification 42 

Cerebellar  falx 538 

Cerebellum 526 

cortical  substance  of 527 

medullary  substance  of. 527 

Cerebral  falx 538 

Cerebro -spinal  axis 503,  513 

liquid 539 

Cerebrum 515 

convolutions  of 515,  516 

cortical  substance  of 516 

crura  of 516 

hemispheres  of 515 

lobes  of 515 

medullary  substance  of 516 

Cerumen 616 

Cervical  vertebrae 99 

triangles 199 

Chambers  of  the  eye 610 

Cheek  bone 83 

Cheeks 275 

Chest 119,  200 

Chlorine 21,     25 

Chloride  of  sodium 28 

of  potassium 28 

Chloro-hydric  acid 28 

Cholesterine...,  29 


648 


INDEX, 


Chondrigen  

26 

Corpuscles   colostrum 

502 

Choroid  coat  

604 

lymph  .. 

1SO 

plexuses  523, 

536 

mucous  

967 

604 

of  blood  

R39 

Chyle 

430 

Pacinian 

510 

receptacle  of 

431 

splenic 

3  9() 

Ciliary  body                      . 

605 

tactile.         .                            511 

630 

motion  

261 

Cortical   layer   of    the   supra-renal 

muscle  

605 

bodies  

466 

processes 

605 

substance  of  cerebellum 

^07 

zone 

612 

of  cerebrum 

516 

Circle  of  Willis 

369 

of  hair 

637 

Circumduction           ...              

47 

of  the  kidneys     

459 

Circumvallate  papillss  

282 

Costal  cartilages  

116 

Clavicle  

129 

Cranial  fossa   anterior  

67 

53 

middle 

68 

Clitoris 

492 

posterior 

68 

Clot  of  blood. 

340 

Cranium 

67 

Coagulum  

340 

vault  of             .  .     . 

69 

Coats  of  the  arteries  

333 

Cream  

509 

of  the  veins  

336 

Creatin  

?9 

Coccyx  

105 

Creatinin  

29 

Cochlea 

624 

Crest  of  bone 

34 

axis  of 

625 

ethmoidal 

56 

Coeliac  axis    . 

384 

frontal 

59 

Collagen  

26 

occipital    ..    .    .        

5?, 

Collarbone  

129 

sphenoidal  

54 

Colon  

315 

urethral  

479 

Colostrum 

502 

Cribriform  fascia                  2^9   241 

°43 

corpuscles 

502 

plate  of  ethmoid  bone 

57 

Column  vertebral                           97 

113 

spot  inferior 

6^3 

Commissure                                  .  ... 

514 

middle      

69?, 

optic 

518 

superior         

69,9, 

great  cerebral  

519 

441 

Cross   occipital 

59 

cord  

514 

Crown  of  head  

184 

of  mouth 

274 

of  teeth                                 

985 

of  the  third  ventricle 

526 

Crus  of  diaphragm    left  

999, 

of  vulva 

492 

ri^ht  .... 

999, 

Companion  veins 

335 

Crura  of  cerebellum  

59,8 

Concha                     

613 

516 

Condyles  

34 

of  diaphragm  

9,9,9, 

occipital  

51 

of  fornix  

591 

of  femur 

149 

Crystalline                      

27 

of  humerus 

133 

lens           ..        

610 

of  inferior  maxillary  bone 

85 

63?, 

Condyloid.  foramen          ...       ... 

51 

637 

134 

Cystic  duct 

3?8 

Confluence  of  the  sinuses  

409 

282 

DARTOS                      ..        

468 

Conjoined  tendon 

215 

486 

Conjunctiva                          .    . 

597 

77 

Connective  tissue 

170 

posterior  

77 

349 

groove                              ...  292, 

9,93 

516 

ligament  .        

9,86 

Coracoid  foramen 

130 

pulp      291, 

?,9?, 

ligament                                        . 

130 

9,99, 

notch 

130 

Dent  at  ed  band  

5?,2 

603 

5?8 

519 

?90 

487 

?,89 

striatum... 

523 

Dermis...         

629 

INDEX. 


649 


Descriptive  anatomy 17 

Diaphragm 221 

Diaphysis  of  bones 42 

Dilatation  of  heart 349 

Disks,  intervertebral 107 

Dorsal  vertebrae 102 

Drum  of  the  ear 616 

Duct,  common  biliary 328 

cystic 328 

hepatic 324,  328 

lachrymo-nasal 91,  600 

lactiferous 501 

of  glands 269 

of  Miiller 489 

pancreatic 320 

parotid 279 

right  lymphatic 430,  432 

spermatic 472 

submaxillary 279 

thoracic 430,  431 

Ducts,  ejaculatory... 474 

Duodenal  glands 312 

Duodenum 309 

Dura  mater 537 


EAR 612 

external 612 

internal 621 

ligaments  of 613,  619 

middle 616 

muscles  of 614,  620 

small  bones  of 618,  619 

wax 616 

Efferent  lymphatic  vessels 429 

Egg 486 

Ejaculatory  ducts 474 

Elastic  tissue 175 

Elbow  joint 144 

Eminence,  nasal 58 

parietal 60 

pyramidal 622 

Eminences,  mammillary 518 

Enamel 285,  289,  290 

organ. 293 

Endocardium 347 

Endolymph 623 

Endosteum 39 

Ependyma 537 

Epidermis 259,  631 

Epigastric  fold 220 

region 299 

Epiglottis 441 

Epiphyses  of  bones 42 

Epiploic  appendages 317 

Epithelium 259 

ciliated 261 

columnar 260 

irregular 260 

pavement 260 

polyhedral 260 

spheroidal 260 

squamous 260 


Erectile  tissue 476 

Ergot 523 

Eruption  of  temporary  teeth 293 

permanent  teeth 294 

Ethmoidal  crest 56 

fissure 59 

gutters 57 

sinuses 57 

wings 56 

Ethmoid  bone 56 

Eustachian  tube 65,  621 

valve 344 

Excretion 267 

Extremities,  lower 238 

upper 223 

Eye 594 

Eyeball 594,  600 

Eyebrow 595 

Eyelashes 597 

Eyelids 595 

Eye  teeth 287 

FACE 87 

Facial  angle 88 

Falciform  process 240,  243 

Fallopian  canal 63 

tube 488 

False  vocal  cords 447 

Falx,  cerebellar 538 

cerebral 538 

Fang  of  tooth 285 

Fascia 182 

cervical 194 

cribriform 239,  241 

crural 239,  241 

deep 224,  239 

perineal 497 

temporal 185 

femoral 239 

ischio-rectal 497 

lata 239 

lumbar 218 

of  the  foot 239 

palmar 225 

pectineal 240,  243 

pelvic 496 

plantar 242 

recto-vesical 497 

sartorial 240,  243 

spermatic 469 

superficial 212,224,  238 

superficial  perineal 497 

superficial  temporal 185 

transverse '. 216,  218 

Fasciculi  of  muscular  fibres  178 

Fat  tissue 176 

Fauces 276 

Femoral  arch 214,  243 

hernia 243,  244 

ring 243 

Femur 148 

Fenestrated  membranes 334 


42 


650 


INDEX. 


Fibre,  muscular 178 

Fibres,  striated  muscular 181 

unstriated  muscular 271 

Fibrils,  muscular 181 

Fibro-cartilage 173 

interarticular 86,  142 

se  tnilunar 1 60 

Fibro-serous  membranes 264 

Fibrous  tissue 167 

Fibula 152 

Filaments,  homogeneous 30 

Fimbriated  extremity  of  Fallopian 

tube 488 

body 522 

Fingers 139 

Fissure  of  the  anus 238 

ethmoidal 59 

glenoid 62 

great  longitudinal 515 

longitudinal,  of  liver 323 

oral 274 

transverse,  of  liver 323 

of  the  vulva 492 

Flesh 178 

Flexion 47 

Flexure,  sigmoid 315,  316 

Fluoride  of  calcium 28 

Fluorine 21 

Fold,  alar 162 

ary teno-epiglottic 445 

axillary 223 

epigastric 220 

glosso-epiglottic 445 

recto-uterine 304,  484 

recto- vesical 304,  463 

semilunar 598 

utero-vesical 463 

vesico-uterine 304,  463,  484 

Follicular  glands 269 

Fontanel,  anterior 74 

lateral 75 

posterior 75 

Fontanels 74 

Foot 148,  157 

arch  of 157 

hollow  of 157 

sole  of 157 

Foramen,  of  bone 34 

anterior  ethmoidal 92 

anterior  palatine 78,  90 

condyloid 51 

coracoid 130 

infra-orbital 77 

jugular 69 

lacerated 68 

obturat  or 1 24 

of  Winslow 302 

optic 55 

oval,  of  sphenoid  bone 56 

of  heart 344 

posterior  ethmoidal 92 

posterior  palatine 90 


Foramen,  quadrate 

rotund 

sphenoidal 

spheno-palatine 

spheno-maxillary 

spinous 

spinal 

stylo-mastoid 

supra-orbital 

Foramina,  inter- vertebral 

great  sciatic 

sacral 

small  sciatic 

Forearm 

Fornix 

Fossa  of  bone 

glenoid 

hemielliptical 

hemispherical 

infra-clavicular 

infra-spinous 

intercondyloid 

ischio-rectal  

jugular 64,  193, 

navicular 

ptery  go-maxillary 

spheno-maxillary 

submaxillary 

subscapular 

supra-clavicular 193, 

supra-spinous 

temporal 

trochanteric 

cranial,  anterior 

middle.... 


posterior 

inguinal,  internal.... 
external 

nasal 

Fourchette 

Fraena,  glosso-epiglottic. 
Fraenum,  inferior  labial. 

lingual  

preputial 

-superior  labial../.... 

Fringes,  synovial 

Frontal  bone 

Front  teeth 

Fundus,  of  gall-bladder. 

of  urinary  bladder.. 

of  uterus 

Furrow,  naso-labial 


220, 
220, 


,49, 


223 

56 

55 

80 

89 

56 

98 

64 

58 

98 

126 

105 

126 

223 

521 

34 

62 

622 

622 

200 

130 

149 

497 

199 

479 

89 

89 

199 

130 

199 

130 

88 

148 

67 

68 

68 

304 

304 

92 

492 

280 

275 

280 

475 

275 

265 

58 

286 

328 

463 

482 

184 


GALL-BLADDER 328 

Ganglia 512 

Gangliated  cord 582 

Gangliform  enlargement  of  the  fa- 
cial nerve 552 

Gangliform  plexus 555 

Ganglion,  inferior  cervical 584 

jugular 555 

middle  cervical 584 


INDEX. 


651 


544 

Glans  of  the  penis 

475 

otic....                              

550 

of  the  clitoris  

493 

petrous  

554 

Glenoid  cavity  

131 

semilunar   of  solar  plexus 

586 

fissure  

6? 

543 

fossa 

62 

546 

tubercle 

fi*? 

550 

Globulin 

97 

583 

Glomerule    renal  . 

460 

512 

Glosso-epiglottic  frseua  

•^80 

309 

folds         

445 

General  anatomy 

17 

Glottis                  

447 

Germinal  eminence 

486 

Glucose           

?8 

spot 

487 

Glvcosren.  .. 

?,7 

vesicle 

487 

Grape  sugar  

?,8 

Gimbernat's  ligament                  215 

243 

Gray  substance  

505 

Glabella.    ... 

183 

Grinders  

>>88 

Gland  

267 

Gristle  '.  

171 

500 

Groin                                              212 

9R8 

parotid  

278 

Groove,  bicipital  

133 

pineal  

526 

dental  292, 

?93 

prostate 

480 

digastric 

6? 

sublingual 

279 

labial 

184 

submaxillary 

279 

labio-mental 

184 

Glands   agminated                       312 

313 

Gubernaculum  of  testicle 

469 

Bartlioline's 

494 

Gullet    

•>97 

bronchial 

436 

Gums  ...         

•>73 

Brunner's 

312 

Gutters,  ethmoidal  

57 

ceruminous 

616 

Guttural  region  

qo 

coeliac  

439 

convoluted  

270 

HAIRS  

636 

Cowper's  

481 

Ham  

?51 

deep  inguinal 

437 

strings 

951 

duodenal 

312 

Hand 

140 

follicular 

269 

Handle  of  sternum 

117 

o-astric 

308 

Hard  palate 

975 

iliac   external 

437 

Head 

183 

internal 

437 

of  bone.  . 

34 

intercostal 

436 

of  muscle 

179 

lachrymal 

598 

Heart  

341 

lingual 

283 

Heel...             

•>38 

lumbar 

438 

Helicine  arteries  

478 

lymphatic                               428 

429 

Helix  

613 

mediastinal   anterior 

436 

Hemispheres  of  the  cerebellum  

597 

posterior    .     .            .... 

436 

of  the  cerebrum  

515 

mesenteric    ...               

438 

Hepatic  cells  

3?6 

mesocolic  '.  

438 

duct  324, 

3?8 

odoriferous 

634 

substance 

3  'M 

palatine 

275 

Hernia 

990 

palpebral 

596 

femoral                                    243 

944 

perspiratory 

633 

inguinal    direct 

991 

Peyer's 

313 

oblique    ... 

990 

popliteal 

437 

Hernial  sac          ...          ...       220 

944 

preputial 

476 

Hilus  of  kidneys  

458 

pulmonary 

436 

of  spleen  

399 

racemose...    . 

270 

of  supra-renal  bodies  

466 

sebaceous  

634 

Hip... 

?1?, 

simple  follicular 

276 

bones 

191 

solitary                           812   313 

318 

joint 

159 

suburethral                            481 

494 

Hippocampus 

fi99 

superficial  inguinal 

437 

Hollow  of  the  foot 

157 

sweat  

633 

of  the  knee  . 

'>38 

tubular...                   .  269,  312, 

318 

Homogeneous  filaments...         .   18. 

30 

652 


INDEX. 


Homogeneous  granules 18,     29 

liquid 18,     29 

membrane 19,     30 

Horns  of  the  lateral  ventricles 522 

Human  anatom}T .".....     17 

Humerus 132 

Humor,  aqueous 610 

vitreous 611 

Humors  of  the  eye 600 

Hyaloid  tunic 612 

Hydrogen 21 

Hymen 490 

Hyoid  bone 96 

Hypochondriac  regions 299 

Hypogastric  region 299 


ILEUM 

Ileo-colic  valve 

Iliac  regions 

Ilium 

Ilio-pectineal  line 

Ilio-pubic  eminence 

Incisors  

Infundibulum 

Inguinal  canal 

fossae,  external 

internal 220, 

hernia,  direct  

oblique 

region 

Innominate  bones 

Inosit 

Instep 

Intermuscular  partitions 

Interposed  velum 524, 

Interver t ebral  disks 

foramina 

ligaments 

notches 

Intestinal  juice 

Intestine 

large 

small  

Iodine 

Iris 

Iron 21, 

Irregular  bones 

Ischium 

plan  e  of 

Ivory 


310 
316 
299 
121 
126 
124 
286 
518 
219 
220 
304 
221 
220 
212 
121 

28 
157 
182 
535 
107 

98 
107 

98 
313 
309 
315 
309 

21 
607 

26 

34 
121 
124 
289 


JAW  BONE,  lower 83 

Jejunum 310 

Joints 46 

Jugular  foramen 51,     69 

fossa 64,  193,  199 

KIDNEYS 458 

Kneecap 150,  238 

joint 160 

Knuckles...  ,.140 


LABIA,  of  the  vulva 492 

Labial  frsena 275 

Labyrinth,  of  ear 621 

membranous 623 

Lacerated  foramen 68 

Lachrymal  apparatus 598 

bone 80 

caruncle 598 

orifice 595,  599 

papillae 595,  599 

point 599 

sac 599 

Lachrymo-nasal  duct 80,     91 

Lacteals 438 

Lamina,  membranous  spiral 626 

osseous  spiral 625 

Laminae  of  the  cerebellum 527 

Larynx 440 

aperture  of 445 

cartilages  of 440 

muscles  of 444,  445 

ventricles  of 445 

Layer,  cellular,  of  membranes 259 

fibrous,  of  membranes 262 

Ligament,  anterior  annular. ...   138,  225 

accessory  of  hip  joint 159 

annular,  anterior,  of  the  wrist..  225 

of  the  radius 145 

of  the  ankle  joint 241,  242 

of  the  ear 616 

of  the  stirrup 619 

posterior,  of  the  wrist 225 

arcuate,  external 218 

astragalo-scaphoid ]  64 

calcaneo-cuboid,  inferior 165 

capsular,   between   radius  and 

ulna 145 

of  ankle  joint 163 

of  astragalus  and  scaphoid 

bone 164 

of  calcaneum  and  cuboid 

bone 165 

of  elbow  joint 144 

of  hip  joint 159 

of  knee  joint 161 

of  scapulo- clavicular   ar- 
ticulation   142 

of  shoulder  joint 143 

of  sterno-clavicular  artic- 
ulation     141 

of  tempero- maxillary  ar- 
ticulation      87 

of  wrist  joint 146 

coraco-acromial 143 

coraco-clavicular 142 

coraco-humeral 1 43 

coracoid 130 

costo-clavicular 142 

costo-transverse,  anterior 119 

middle  and  posterior 119 

costo-xiphoid 119 


INDEX. 


653 


Ligament,  cotyloid 159 

dental 286 

denticulat e 537 

external  calcaneo-scaphoid 165 

lateral,  of  ankle  joint 164 

of  the  jaw 87 

of  elbow  joint 145 

of  knee  joint 162 

of  wrist  joint 146 

glenoid 143 

great  sacro-sciatic 126 

ilio-lumbar 126 

inferior  calcaneo-cuboid 165 

calcaneo-scaphoid 1G<5 

inter-articular,  of  rib 118 

inter-clavicular 142 

internal  lateral,  of  ankle  joint..  164 

of  elbow  joint 145 

of  knee  joint 162 

of  wrist  joint 146 

interosseous,  of  tarsal  bones...   164 

left  lateral,  of  liver 302,  321 

long  plantar 166 

nuchal Ill 

of  the  patella 161,  249 

ovarian 485 

palmar,  of  lingers 147 

ptery  go-maxillary 190 

radiating 118 

round,  of  hip  joint 159 

of  ulna  and  radius 145 

of  uterus 484 

right  lateral,  of  liver 302,  321 

small  sacro-sciatic 126 

spheno-m  axillary 1 95 

stylo-hyoid 64,     96 

stylo-maxillary 194 

superior  calcaneo-cuboid 165 

supra-spinous Ill 

sub-pubic 125 

suspensory,  of  the  anvil 619 

of  the  clitoris 493 

of  the  liver 302,  321 

of  the  mallet 619 

of  the  penis 476 

of  the  spleen 302,  329 

thyro-epiglottic 443 

transverse 112 

triangular 497 

vertebral,  anterior 109 

posterior 110 

Ligaments,  acromio-clavicular 142 

anterior  of  the  bladder 463 

arcuate 221 

atlo-axoid,  anterior 112 

posterior 112 

band-like 48 

broad,  of  the  uterus 304 

capsular 48 

of  the  costal  cartilages 119 

of  the  ribs 118,   119 

costo-sternal 119 


Ligaments,  crucial 161 

dorsal 147,   165 

interosseous 147 

of  metatarsus 165 

of  tarsus 165 

interspinous Ill 

intervertebral 107 

lateral,  of  the  bladder.... 463 

lateral,  of  phalanges 147 

occipito-atloid,  anterior Ill 

posterior Ill 

odontoid 113 

of  the  ear 013,  619 

of  the  liver 301,  302,  321 

of  the  metatarso-phalangial  ar- 
ticulations    1 66 

of  the  phalangial  articulations..  166 
of    the    tibio-fibular    articula- 
tions   163 

of  the  uterus 484 

of  the  urinary  bladder 463 

of  the  larynx 442 

palmar ' 147 

palpebral 596 

sacro-iliac 126 

sterno-clavicular 142 

thyro-hy oid 442 

vaginal,  of  fingers 226 

of  the  toes 242 

yellow 109 

Linea  aspera 148 

alba 217 

Line,  median,  of  abdomen 217 

semilunar,  of  abdomen 217 

Lines,  transverse,  of  abdomen 217 

Lime,  phosphate  of 28 

carbonate  of 28 

oxalate  of 29 

Lingual  fraenum 280 

Lips 274 

of  the  uterus 482 

Liquid,  cerebro-spinal 539 

Liquor  sanguinis 340 

Liver :JOO,  321 

Lobes  of  a  gland 270 

of  the  cerebrum 515 

of  the  liver 322,  323 

of  the  lungs 451 

of  the  prostate  gland 480 

Lobules  of  glands 270 

of  the  liver 271,  325 

of  lungs,  primary 452 

secondary 452 

Loins 211 

Lower  jaw  bone 83 

Lumbar  regions 211,  299 

vertebrae 103 

Lungs 450 

Lunula 641 

Lymph 430 

corpuscles 430 

Lymphatic  system 428 


654 


INDEX. 


Lymphatic  glands 428,  429 

anterior  auricular 434 

axillary 435 

bronchial 436 

coeliac 439 

deep  cervical 434 

deep  inguinal 437 

external  iliac 437 

intercostal 436 

internal  iliac 437 

internal  maxillary 434 

lumbar 438 

mediastinal,  anterior  436 

posterior 436 

mesenteric 438 

mesocolic 438 

occipital , 433 

popliteal 437 

posterior  auricular 433 

pulmonary 436 

submaxillary .'  434 

superficial  cervical 434 

inguinal 437 

trunk,  broncho-mediastinal 436 

intestinal 439 

vessels 428 

anterior  mediastinal 436 

deep  cervical 434 

deep  facial 434 

intercostal 435 

lingual 434 

occipital 433 

of  the  exterior  of  the  tho- 
rax   435 

of  the  large  intestines 438 

of  the  liver 438 

of  the  lower  extremities...  437 

of  the  stomach 438 

of  the  upper  extremities...  435 

pulmonary 436 

superficial  cervical 434 

facial 434 

temporal 433 

MAGNESIA,  phosphate  of 28 

Magnesium 21,  26 

Malar  bone 83 

Malleolus,  internal 152 

external 153 

Mallet 618 

Malpighian  corpuscles 460 

Mammae 499 

Mammillary  eminences 518 

Manganese.. 21 

Margarin 27 

Marrow 36,  39 

Mastoid  portion  of  temporal  bone...  62 

process 62 

sinuses 62,  620 

Matrix  of  nails 640 

Maxillary  bone,  inferior 83 

superior 76 


Maxiliary  sinus 

Meatus 

external  auditory 63, 

inferior,  of  the  nose 

internal  auditory 63, 

middle,  of  the  nose 57, 

superior,  of  the  nose 57, 

Mediastinal  cavities. . . ; 

Mediastinum  of  the  testis 

Mediastinum 

Medulla 36, 

oblongat  a 

Medullary  cavity 

sheath 

substance  of  kidney 

of  supra-renal  bodies 

Melanin 

Membrane,  arachnoid 

basement 

fenestrat  ed 

mucous 

of  the  aqueous  humor 603, 

of  the  tympanum 

perforated 

pupillary 


synovial 48, 

thyro-hy  oid 

tympanic 

vocal 

Membranous  labyrinth 

portion  of  urethra 

semicircular  canals 

Mesentery 301, 

Mesocolon,  ascending 301, 

descending 301 , 

transverse 301 , 

Mesorectum 301 , 

Metacarpal  bones 

Metacarpus 

Metatarsal  bones 

Metatarsus 

Milk 

globules 

plasma 

Mineral  bodies 

Mitral  valve 

Molars 

Mons  veneris 

Motion,  ciliary 

Mouth 

floor  of  the 

roof  of  the 

Mucus 

Mucous  corpuscles 

membrane 

gastro-pulmonary 

genito-urinary 

mammary 

nasal 

Muscle,  accessory  flexor 

adductor,  great v.. 


<6 

34 
615 

94 
627 

93 

93 
454 
470 
454 

39 
530 

30 
505 
459 
466 

27 
539 

334 
266 
610 
616 
334 
608 
263 
265 
442 
616 
443 
623 
479 
623 
303 
303 
303 
303 
304 
138 
138 
156 
156 
502 
502 
502 
18 
347 
288 
491 
261 

278 
275 
267 
267 
266 
266 
266 
266 
593 
256 
250 


Muscle   adductor  long 

INE 

249 
257 
237 
258 
236 
250 
499 
499 
229 
445 
228 
250 
229 
190 
498 
605 
499 
208 

296 
296 
295 
228 
469 
444 
444 
444 
249 
227 
189 
190 
196 
206 
190 
189 
277 
205 
189 

233 
235 
253 
235 
235 
252 
253 
235 

235 

238 
233 
234 
191 
232 
256 
237 
232 
255 
236 
258 
257 
236 

EX.                                            655 

Muscle,  flexor,  snort,  of  the  toes  256 
superficial,  of  fingers  231 

of  the  great  toe             

gastrocnemius 

254 

of  the  little  toe 

geminous  

246 

genio-glossal  

284 

short 

genio-hyoid   

197 

inal  elevator 

gluteal,  grea  t  

244 

middle 

anconeous                      .            ... 

small  

245 

gracilis 

248 

biceps  flexor  

great  serrated  

202 

biceps  flexor  of  thigh 

pectoral 

201 

hyo-^lossal 

284 

-      iliac 

247 

bulbo-urethral 

inferior  oblique 

209 

ciliary                                    187 

serrated 

.  206 

coccygeal                                  .  • 

infra-spinous 

complex                              

internal  pterygoid  

..  191 

constrictor  of  the  pharynx,  in- 
ferior      

interosseous  of  the  foot., 
ischio-cavernous  

...  258 

.      ..  498 

middle            ....  

labio-nasal  depressor  
elevator 

189 
188 

coraco  brachial  

larger  straight  anterior  . 
posterior  

198 
209 

crico-arytenoid  lateral 

larger  zygomatic  
lateral  straight  
latis^imus 

189 
209 

204 

posterior                               . 

crico-thyroid 

cruralis 

laxator 

620 

deltoid                           

lingual 

284 

depressor  of  the  lower  lip  

long  cervical 

198 

of  the  oral  angle  

lumbrical 

232,  256' 
191 

digastric            

masseter.  .  . 

dorsal  extensor  

multifid  spinal 

208 
197 

elevator  of  the  lower  lip  
of  the  oral  angle  

mylo-hyoid  ..    .. 

nasal  compressor  . 

188 

of  the  palate  

dilator... 

188 

of  the  scapular  angle  
of  the  upper  lip  

pyramidal    . 

186 

oblique,  external. 

213 

extensor,  common,  of   the  fin- 
gers 

inferior  

602 

internal 

metacarpal,  of  thumb  
of  the  great  toe.        

superior    

..    .  .  601 

obturator,  external  
internal 

246 
246 

of  the  index  finger      

of  the  little  finger  

occipito-frontal 

185 

of  the  toes  long  

omo-hyoid 

196 

oral  orbicular 

188 

phalangial,  of  thumb,  first, 
phalangial,  of  thumb,  sec- 

palato-glossal 

278 

pharyngeal 

295 

palmar,  long 

230 

radio-carpal,  longer  
radio-carpal,  shorter  

short  

palpebral  elevator. 

187 

ulno-carpal  

orbicular  

187 

external  pterygoid  

pectineal  

.    .    .   249 

flexor  deep   of  fingers. 

peroneal,  anterior  
lonsr 

252 
.......  253 

long  of  great  toe.  . 

of  little  finger  
of  the  thumb   . 

short  

plantar  . 

of  the  toes. 

popliteal  ..  . 

255 

metacarpal,  of  thumb  
of  the  little  toe 

posterior  tibinl 

256 

psoas  

247 

short,  of  great  toe  
of  the  thumb..., 

small 

247 

pyramidal  ... 

..   217 

656 


INDEX. 


Muscle,  pyriform 246 

quadrate  femoral 246 

lumbar 218 

pronator 230 

quadriceps  extensor 249 

radio-carpal  flexor 230 

rectus 249 

rhomboid 205 

sacro-lumbar 207 

sartorius 248 

scalene,  anterior 197 

middle 197 

posterior 198 

semi-membranous 251 

semispinal 208 

semi-tendinous 250 

smaller  straight,  anterior 198 

straight  posterior 209 

small  pectoral 202 

zygomatic 189 

soleus 254 

splenius 207 

stapedius 620 

sterno-costal 210 

sterno-hyoid 195 

sterno-mastoid..... 195 

sterno-thyroid 196 

straight,  of  abdomen 216 

stylo-glossal 284 

stylo-hyoid 196 

stylo-pharyngeal 295 

subclavian 202 

subcutaneous  cervical 193 

subscapular 226 

superciliary 187 

superior  oblique 209 

serrated 205 

supinator,  long 233 

short 235 

supra-spinous 226 

tarsal  tensor 187 

temporal 192 

tensor  of  the  ear 620 

of  the  femoral  fascia 248 

of  the  palate 278 

terete,  greater 227 

lesser 226 

pronator 230 

thyro-arytenoid 444 

thyro-hyoid 196 

tibial,  anterior 252 

trachelo-mastoid 208 

transverse 215 

of  foot 258 

transverse  perineal 499 

trapezius 203 

triceps  extensor 229 

sural 254 

ulno-carpal  flexor 230 

uvular 278 

vaginal  constrictor 498 

vastus,  external 249 


Muscle,  vastus,  internal 249 

Muscles 178 

ciliary 605 

costal  elevator 210 

form  of 179 

head  of 179 

insertion  of. 179 

intercostal 210 

interosseous  of  the  hand 237 

inter-spinal 209 

inter-transverse 209 

of  eyeball 601 

of  the  larynx 443 

origin  of 179 

pectinate  344 

straight 601 

Muscular  fibres 178 

striated 181 

unstriated 271 

fibrils 181 

Myolemma 181 

Myrtiform  caruncles 490 

NAILS 640 

Nares 92,  184,  588 

Nasal  bone 81 

cavities 92,  591 

fossae 92 

meatuses 93,  591 

notch 77 

orifices 92 

partition 591 

plate ,.  79 

process 77 

septum 92 

spine 77 

Nates 238 

Navel 212 

Navicular  fossa 479 

Neck 193 

Nerve,  auriculo-temporal  548 

capsular  bodies 510 

cells 505 

circumflex 568 

crural 574 

cutaneous,  external 566 

internal 566 

small 566 

deep  auricular 552 

dorsal  of  penis 578 

clitoris 578 

external  cutaneous,  of  lumbar 

plexus 574 

fibres 504,  508 

frontal 544 

genito-crural 573 

great  auricular 563 

sciatic 578 

ilio-hypogastric 573 

ilio-inguinal 573 

inferior  dental 549 

hsemorrhoidal 577 


INDEX. 


657 


Nerve  inferior  maxillary            ~>43 

548 

Nerves,  fibres  of..      .  . 

508 

infra-orbital 

552 

ganglionic  system  of  . 

512 

intercosto-  humeral 

572 

glosso-pharyngeal  

553 

internal  cutaneous  of  crural  . 

576 

hypoglossal  

559 

lachrymal 

544 

inferior  gluteal  

578 

lingual 

548 

infra-orbital  

546 

576 

intercostal 

571 

median.  .         

568 

lary  ngeal  

557 

575 

lumbar 

572 

musculo-cutaneous 

579 

oculo-motor  

541 

musculo-spiral 

570 

olfactory.          

540 

nasal                                       544 

547 

ophthalmic  

543 

obturator 

574 

optic  

541 

perineal 

578 

origin  of  

509 

peroneal  communicating 

581 

palatine  

547 

phrenic  ... 

563 

pathetic  

542 

popliteal,  external  

579 

phary  ngeal  

..  557,  583 

internal  

579 

plantar  

581 

posterior  interosseal  

570 

plexuses  of  

508 

pterygoid... 

547 

pneumogastric  

555 

pudendal 

578 

pulmonary 

557 

pudic 

577 

real  origin  of 

510 

radial 

570 

sacral 

576 

short  saphenous. 

580 

spheno-palatine 

546 

small  occipital  . 

563 

spinal 

514    559 

petrosal  

550 

subscapular        ... 

566 

sciatic  

578 

superficial  origin  of. 

510 

splanchnic,  great  

585 

supra-clavicular  

563 

small  

585 

termination  of.  

.  509 

third 

585 

thoracic 

565    570 

superficial  cervical 

563 

vestibular 

628 

superior  gluteal 

577 

Nervous  system 

503 

maxillary 

545 

Neurilemma 

60S 

temporal 

552 

Nipple 

500 

temporo-malar 

546 

Nitrogen 

21      25 

tibial   anterior 

579 

Nose 

588 

posterior. 

581 

back  of 

184 

trifacial  

542 

bridge  of 

184 

tympanic..                552, 

554 

cartilages  of 

590    591 

ulnar      

568 

column  of 

184 

zygomatic  

552 

meatuses  of. 

591 

Nerves  

503 

root  of  

184 

abdu  cent  

550 

sinuses  of  

591 

accessory  

558 

winf  s  of  

591 

apparent  origin  of.  

510 

Nostrils  

184 

auditory 

553 

Notch   coracoid 

130 

cochlear  branch  of.  

6?6 

great  sciatic  

122 

vestibular  branch  of.  

6^,3 

lesser  sciatic  

123 

cardiac 

557 

nasal 

77 

inferior                          .     ... 

584 

semilunar 

85 

middle                          

584 

Nucleolus.    .    .. 

23 

superior  

583 

Nucleus  

23 

cerebral  514, 

540 

lenticular  

523 

cerebro-spinal  507, 

514 

Ny  mphae  

493 

cervical 

561 

coccygeal 

576 

OBTURATOR  FORAMEN 

124 

ciliary 

544 

membrane 

125 

cochlear  .       . 

628 

Occipital  angle 

52 

deep  origin  of.    

510 

bone  

50 

dental  

546 

cross... 

52 

digital  

581 

protuberances 

52 

facial.  .  . 

551 

region... 

91 

658 


INDEX. 


Odontoid  ligaments 113 

process 101 

(Esophageal  orifice 222 

(Esophagus 297 

Olecranon 135 

Olein 27 

Olfactory  region 593 

Olivary  bodies 530 

Omentum,  gastro-colic 303 

gastro-hepatic .'....  301,  302 

gastro-splenic 303,  329 

great. 301,  303 

Optic  commissure 518,  541 

tract 541 

Orbital  entrance 91 

plate 77 

Orbits 91 

Organic  cells 22 

Organized  bodies 18 

Orifice,  aortic 222 

auriculo-ventricular 344 

cesophageal 222 

urethral 480 

Orifices  of  the  ureters 464 

Origin  of  nerves 510 

Osseous  tissue 40 

Ossification 42 

centres  of 42 

Otolites  624 

Oval  foramen,  of  heart 344 

sphenoid  bone 56 

Oval  window 618 

Ovarian  ligament 485 

Ovaries 485 

Oviduct 488 

Ovisacs 486 

Ovum 486 

Oxalate  of  lime 29 

Oxygen 21,     25 

PACINIAN  CORPUSCLES 510 

Palate 275 

half  arches  of 276 

bone 78 

Palatine  region 90 

Palm 140,  223 

Pancreas 300,  320 

Pancreatic  juice 321 

Pancreatin 27,  326 

Papillee  of  taste 282 

tactile 630 

Papillary  muscles 345 

Parietal  bone .     60 

Parotid  gland 278 

Paro  varium 487 

Partitions,  intermuscular 182,  239 

Patella 150 

Pavilion 488 

Pectinate  muscles 344 

Pectineal  line 123 

Pedicle,  olfactory 540 

Peduncles  of  cerebellum 528,  529 


Peduncles  of  pineal  gland 526 

Pellucid  septum 521 

Pelvis 126 

cavity  of 494 

of  kidney 461 

Penis  * 475 

Pepsin 27,  309 

Pericardium 349 

Perilymph 623 

Perineum 496 

Periosteum 39 

Peritoneum 300 

Permanent  teeth 286 

Petrous  portion  of  temporal  bone...     63 

Peyer's  glands 313 

Phalanges  of  foot 157 

of  hand 139,  140 

Phalanx 139 

Pharynx 294 

Phosphorus 21 

Pia  mater  of  brain 535 

of  spinal  cord 536 

Pimplemite 636 

Pineal  gland 526 

Pit  of  the  stomach  200,  212 

Pituitary  body.. 518 

fossa 53 

Plane  of  the  ischium 124 

Plate,  nasal 79 

of  malar  bone 83 

orbital 57,  59,     77 

palate 78,     79 

Pleura 454 

Plexus,  aortic 586 

brachial 563 

cardiac 584 

carotid 583 

cavernous 583 

cervical 562 

choroid 523,  536 

coronary  586 

dorsi- spinal 423 

ganglitorm 555 

hsemorrhoidal ,  319,  424 

hepatic 586 

hy pogastric 587 

intra-spinal  423 

lumbar 573 

mesenteric,  inferior 586 

superior 586 

cesophageal 558 

pampiniform 473 

pharyngeal  583 

phrenic 586 

prost atic 424 

pulmonary 557 

renal 586 

reteform 471 

sacral  577 

solar 585 

spermatic 586 

splenic 586 


INDEX. 


659 


Plexus,  supra-renal 586 

uterine 587 

utero- vaginal 424 

vesical 425 

vesico-prostatic 587 

vesico  vaginal 587 

Plexuses,  nervous 508 

venous 336 

Pons 529 

Popliteal  region 238,  251 

Potassa,  carbonated 28 

phosphate  of 28 

urate  of 29 

Potassium 26 

chloride  of. 28 

Poupart's  ligament 242 

Premolars 287 

Preperitoneal  cavity 217 

Prepuce  of  clitoris 493 

of  penis 475 

Process,  angular,  external 58 

internal 58 

articular,  of  temporal  bone..  ..     64 

auditory 63 

basilar 51 

ciliary 605 

clinoid,  anterior 53 

posterior 53 

coracoicl 132 

coronoiil 85,  135 

falciform 243 

frontal 83 

lateral,  of  calcaneum 154 

long,  of  the  mallet 619 

malar 78 

inastoM 62 

nasal 77 

odontoid 101 

of  bone •. 34 

olivary 53 

orbicular 619 

orbital 80 

pterygoid,  external 55 

internal 55 

pyramidal 80 

short,  of  the  mallet 619 

sphenoidal 80 

spinous 34 

of  ilium,  anterioi 122 

posterior 122 

superior  122 

of  radius 136 

of  sphenoid  bone 55 

of  temporal  bone 63 

of  the  tibia 151 

of  vertebrae 98 

styloid,  of  ulna 135 

transverse,  of  occipital  bone...     51 

transverse,  of  vertebrie 98 

turbinated,  inferior 67 

superior 57 

vaginal 63 


Process,  vermiform 527 

Promontory 617 

of  the  pelvis 126 

Prostate  gland 480 

Prostatic  portion  of  urethra 478 

Protuberance,  occipital,  external....  52 

internal 52 

mental 84 

zygomatic 62,  83 

Ptyalin '. 27 

Pubic  symphysis 125 

arch  ...,. 127 

Pubis 121,  123 

Pulp  of  cavity 286 

of  teeth 286 

of  the  spleen 330 

Pulsation 350 

Pulse 350 

Pupil 607 

Pulmonary  circulation 350 

Pyloric  extremity  of  stomach 305 

orifice 305 

sphincter 306 

valve  307 

Pyramidal  bodies 530 

Pyramid  of  the  tympanum 618 

Pyramids,  decussation  of 531 

posterior 531 

renal 459 

QUADRATE  FORAMEN 223 

RADIUS 135 

Kami  of  pubis 123 

Ramus  of  ischium 123 

Raphe  of  perineum 496 

of  scrotum 468 

of  tongue 280 

Receptacle  of  chyle 431 

Rectum  318 

Region,  guttural 90 

occipital 91 

oral 90 

palatine 90 

Regions  of  the  abdomen 299 

Renal  glomerule   460 

papillae 459 

pyramids 459 

Restiform  bodies 531 

Reteform  plexus 471 

Retinn 608 

Ribs  114 

Ridge,  asperous 148 

inter-trochanteric 148 

molar 84 

of  bone 34 

superciliary 58 

temporal 61,  88 

Ring,  external  abdominal 213,  219 

internal •. 219 

Root  of  lungs 450 

of  hairs  ....>.-...> 636 


660 


INDEX. 


Rostrum 54 

Rotation 48 

Rotund  foramen 5G 

Round  window 618 

SAC,  LACHRYMAL 599 

Saccule,  spherical  623 

elliptical 623 

Sacrum 104 

Saliva 280 

Saphenous  opening 240 

Scala,  tympanic  626 

vestibular 626 

Scalp 184 

Scapula 130 

Sclerotica  602 

Sclerotic  coat 602 

Scrotum 468 

Sebaceous  glands 634 

matter 635 

Secondary  tympanic  membrane 618 

Secretion 267 

Semen 474 

Semi-bulbs  of  the  clitoris 493 

Semicircular  band 524 

canals 622 

membranous 623 

Semilunar  fibro-cartilages 160 

folds 598 

valves 346,  347 

Seminal  liquid 474,  472 

vesicles 473 

Seminiferous  tubules 471,  472 

Septal  fibres  531 

Septula  of  testicles 470 

Septum,  osseous  nasal 92 

pellucid 521 

Serum 340 

Sexual  differences  of  the  pelvis 128 

Shaft  of  bone 34 

Shin 151 

Shin  bone 150 

Shoulder  blade 130 

Sigmoid  flexure  of  the  colon 315 

Sinews 180 

Sinus,  anterior  occipital 411 

cavernous 411 

circular 418 

circular,  of  the  iris 601 

frontal 60 

inferior  longitudinal 410 

petrosal 411 

lateral 409 

maxillary 76 

of  bone 34 

posterior  occipital 412 

straight 410 

superior  longitudinal 410 

petrosal 411 

Sinuses,  sphenoidal 54 

ethmoidal 57 

lactiferous 501 


Sinuses,  mastoid 62,  620 

of  dura  mater 409,  538 

venous 336 

Soda,  carbonate  of 28 

phosphate  of. 28 

taurocholate  of 29 

urate  of 29 

Sodium 21,     25 

chloride  of 28 

Skeleton 33 

Skin : 628 

Skull 85,     87 

Smegma 476 

Soft  epidermic  layer 633 

Soft  palate 275 

Solar  plexus 585 

Sole 157 

Space,  anterior,  perforated 519 

posterior  "         518 

Special  anatomy 17 

Sperm  cells 472 

Spermatic  cones 471 

cord 469 

duct 471,  472 

liquid. 472 

Spermatozoids  474,  472 

Sphenoid  bone 52 

Sphenoidal  foramen 55 

Spinal  cord 513,  533 

columns  of 534 

commissures  of 533 

fissures  of.  533 

gelatinoid  substance  of. 535 

gray  substance  of 505 

horns  of  534 

white  substance  of  504 

Spine,  nasal 77 

of  scapula 131 

palate 79 

Sphincter  of  the  anus 319 

of  the  bladder 464 

Spinous  foramen 56 

Spiral  lamina,  osseous 625 

membranous 626 

tract 628 

Spleen 329 

Splenic  corpuscles 330 

Spongy  body,  of  clitoris 493 

of  penis 477 

portion  of  urethra 479 

Squamous  portion  of  temporal  bone.     61 

Sternum 117 

Stirrup 619 

Stomach 305 

pit  of 211 

position  of 299 

Strait,  inferior,  of  pelvis 127,  494 

superior  "         127,494 

Striated  body 523 

Stroma  of  the  ovary 485 

Sub-arachnoid  space 539 

Sub-arachnoid  tissue 264 


INDEX. 


661 


Submaxillary  gland... 279 

Sub-mucous  tissue 266 

Sub-serous  tissue  264 

Substance  of  bone 36 

Superciliary  ridge 58 

Supra  renal  bodies 465 

Sutures 46,  66 

dentated 46 

of  the  cranium 66 

of  the  face 86,  90 

serrated 46 

squamous 46 

Sweat 634 

duct 633 

glands 633 

Sylvian  fissure 515 

Sympathetic  system  of  nerves 581 

Syrnphysis 46 

of  inferior  maxillary  bone. 84 

pubic 125 

sacro-iliac 125 

Synovia 49,  265 

Synovial  burssB 183,  265 

fringes 49,  265 

membranes 48,  265 

Systemic  circulation 351 

TACTILE  CORPUSCLES 511,  630 

papillae 630 

Tapetum 607 

Tarsal  bones 153 

Tarsus 153 

Teeth 285 

bicuspid 287 

canine 287 

eruption  of 293 

eye 287 

front 286 

jaw 288 

milk 288 

permanent 285,  286 

stomach 287 

temporary 285,  288 

Temple 183 

Temporal  bone 61 

fossa 88 

regions 183 

Tendinous  cords 346 

Tendon  of  Achilles 254 

Tendons 178,180,  182 

Tentorium 538 

Testicles 468 

Thalami 524 

Thalamus 524 

Thoracic  aorta 381 

duct 431 

Thorax 119 

Throat 193,  294 

Thymus  body..  456 

Thyroid  body 455 

cartilage  440 

Tibia...  .  150 


Tissue,  adipose 176 

areolar 170 

connective  170 

elastic 175 

fat 176 

fibrous 167 

sub-archnoH 264 

sub-serous 264 

Toes 157 

Tongue 280 

Tonsils 276 

Tonsils  of  the  cerebellum 528 

Topographical  anatomy 17 

Trabeculse  of  penis  476 

of  spleen , 330 

Trachea 447 

Tract,  spiral 628 

Tricuspid  valve 345 

Trochanters 148 

Trunk  of  skeleton 96 

Tubercle 34 

mental 84 

Tuberosity 34 

Tunics  of  the  eye 600 

Turbinated  bone 81 

Tympanic  membrane 616 

secondary 618 

Tympanum 616 

ULNA 134 

Umbilical  region 299 

Umbilicus 212 

Urachus 463 

Urea 29,  462 

Ureter 461 

Ureters 458 

Urethra 465,  478 

Urinary  bladder 462 

Urine 462 

Uriniferous  tubules 460 

Uroerythrin 29 

Uterus 481 

Utricle 474 

Uvula 275 

of  the  cerebellum 528 

vesicle 464 

VAGINA 489 

Valley 527 

Valve,  ileo-colic 316 

mitral 347 

of  the  brain.... 529 

pyloric 307 

tricuspid 345 

Valves  of  veins 336 

semilunar 346,  347 

Valvulse  conniventes 266,  310 

Vasdeferens 472 

Vein,  angular  414 

axillary 417 

azygos 419 

basilic ..  418 


662 


INDEX. 


Vein,  cardiac   anterior 

406 

Veins   cerebellar   superior 

41° 

posterior  . 

406 

cerebral    inferior 

412 

cephalic  

418 

internal 

412 

coronary  

405,  422 

median 

41'> 

cystic  

422 

superior. 

'11  *> 

dorsal  lingual 

416 

common  iliac 

493 

of  clitoris  

425 

companion  

335 

of  penis 

425 

diploic                                     41o 

493 

facial  

414 

dorsi-spinal  plexus  of 

d°S 

femoral  

426 

hsemorrhoidal  plexus  of 

I'M 

frontal  

414 

hemi-azygos  

419 

iliac  external 

425 

hepatic 

421 

internal 

424 

inferior  palpebral 

414 

innominate,  left  

406 

innominate 

406 

right  

406 

intercostal  left 

4*>0 

internal  maxillary  

415 

right  .     .  . 

419 

jugular,  anterior  

413 

internal  mammarv. 

407 

external 

413 

intra-spinal  plexus  of 

•12'-? 

internal 

408    409 

jugular 

•108 

posterior. 

413 

labial 

114 

mastoid  

416 

longitudinal  anterior 

4'>3 

median  basilic  

419 

posterior     

4^3 

cephalic  

419 

lumbar  

491 

mesenteric,  inferior.... 

422 

masseteric  .... 

414 

superior 

422 

median 

1  1  9 

middle  sacral 

420 

meningeal 

•113 

occipital                          . 

416 

nasal 

41  4 

ophthalmic 

413 

O3sophau'eal 

419 

palatine  

414 

ovarian  ..           

vn 

pharyno"<?al  

416 

parotid  

415 

popliteal  

426 

phrenic  

4?1 

portal 

405    421 

prostatic  plexus  of 

<1°4 

posterior  auricular 

415 

pulmonary                    405    428 

453 

pudic 

425 

renal 

491 

radial  cutaneous 

.  418 

spermatic  

491 

ranine....                 

416 

submaxillary  

414 

right  bronchial  

419 

superficial,  of  lower  extremity. 

4°6 

gastro-epiploic  

422 

upper  extremity  

417 

saphenous    long 

426 

superior  palpebral 

414 

short 

426 

thyroid    . 

416 

splenic 

422 

supra-renal         .            .  .  ' 

491 

subclavian                   ... 

417 

ulnar  cutaneous  

415 

submental  .           

414 

uterine  

4?5 

supra-orbital  

414 

utero-vaginal  plexus  of  

4?,4 

supra-scapular 

413 

valves  of 

336 

tempero-maxillary 

415 

vesical  plexus  of       .        .... 

4?5 

temporal 

.     .  414 

Velum   interposed...                .  .  524, 

535 

anterior 

414 

Venous  plexuses  

336 

415 

sinuses 

336 

414 

Ventricle  fifth 

5?1 

407 

fourth 

531 

transverse  cervical 

413 

third...             

F»?3 

facial 

415 

Ventricles,  lateral  

r>v»l 

vertebral                        . 

407 

of  the  heart  

343 

Veins                                  .  ... 

...   335,  405 

of  the  larynx  

445 

articular.            

415 

Vermiform  appendix  

315 

auricular  anterior 

415 

process    

5?,7 

brachial 

417 

Vertebrae  

97 

453 

cervical 

99 

414 

dorsal                                  

10?, 

406 

false                .     ...        

103 

cerebellar,  inferior.... 

..  412 

lumbar  

103 

INDEX. 


663 


Vertebras,  true 97 

Vertebral  column 1)7,  113 

Vertex 184 

Vesical  sphincter 464 

triangle 464 

uvula 464 

Vesicles,  seminal 473 

Vesico-uterine  pouches o04 

folds 304 

Vessels  afferent 429 

efferent 429 

lymphatic 428 

Vestibule 494 

of  the  ear 621 

of  the  labyrinth 621 

Villi 311 

Vitelline  membrane 487 

Vitreous  humor 611 

table  of  bone 65 

Vocal  cords 443,  446 

false 447 

membrane...                              ..  443 


Vomer 82 

Vulva 491 

WHITE  SUBSTANCE 505 

of  the  eye 598,  602 

Windpipe 447 

Window,  oval 618 

round 618 

Wings  of  the  sphenoid  bone 54 

ethmoidal 56 

Womb 481 

Wrist 136 

joint 146 

YELK 487 

Yellow  ligaments 109 

spot 609 

ZONE,  ciliary 612 

Zygoma 62 

Zygomatic  arch 88,     89 


14  DAY  USE 


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LD  21-50m-6,'59 
(A2845slO)476 


General  Library 

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